Timothy Colmer

Tolerance of wheat (Triticum aestivum cvs Gamenya and Kite) and triticale (Triticosecale cv. Muir) to waterlogging

Publisher: Wiley

Date: 03-1992

DOI: 10.1111/J.1469-8137.1992.TB01073.X

Tolerance to partial and complete submergence in the forage legume Melilotus siculus: an evaluation of 15 accessions for petiole hyponastic response and gas-filled spaces, leaf hydrophobicity and gas films, and root phellem

Publisher: Oxford University Press (OUP)

Date: 16-08-2019

DOI: 10.1093/AOB/MCY153

Submergence tolerance and recovery in Lotus

Publisher: Elsevier BV

Date: 06-2020

DOI: 10.1016/J.JPLPH.2020.153180

Resequencing of 429 chickpea accessions from 45 countries provides insights into genome diversity, domestication and agronomic traits

Publisher: Springer Science and Business Media LLC

Date: 29-04-2019

DOI: 10.1038/S41588-019-0401-3

Abstract: We report a map of 4.97 million single-nucleotide polymorphisms of the chickpea from whole-genome resequencing of 429 lines s led from 45 countries. We identified 122 candidate regions with 204 genes under selection during chickpea breeding. Our data suggest the Eastern Mediterranean as the primary center of origin and migration route of chickpea from the Mediterranean/Fertile Crescent to Central Asia, and probably in parallel from Central Asia to East Africa (Ethiopia) and South Asia (India). Genome-wide association studies identified 262 markers and several candidate genes for 13 traits. Our study establishes a foundation for large-scale characterization of germplasm and population genomics, and a resource for trait dissection, accelerating genetic gains in future chickpea breeding.

Investigating drought tolerance in chickpea using genome-wide association mapping and genomic selection based on whole-genome resequencing data

Publisher: Frontiers Media SA

Date: 19-02-2018

DOI: 10.3389/FPLS.2018.00190

Root O2 consumption, CO2 production and tissue concentration profiles in chickpea, as influenced by environmental hypoxia

Publisher: Wiley

Date: 28-01-2020

DOI: 10.1111/NPH.16368

Abstract: Roots in flooded soils experience hypoxia, with the least O

Friend or Foe? Chloride Patterning in Halophytes

Publisher: Elsevier BV

Date: 02-2019

DOI: 10.1016/J.TPLANTS.2018.11.003

Abstract: In this opinion article, we challenge the traditional view that breeding for reduced Cl

Changes in physiological and morphological traits of roots and shoots of wheat in response to different depths of waterlogging

Publisher: CSIRO Publishing

Date: 2001

DOI: 10.1071/PP01089

Abstract: The growth reduction of wheat (Triticum aestivum L.) during and after waterlogging stress depends on the depth of water from the soil surface. In a pot experiment with 3-week-old plants, soil was waterlogged for 14 d at the surface, or at 100 or 200 mm below the surface, and pots were then drained to assess recovery. A fully drained treatment kept at field capacity served as control. During waterlogging, the relative growth rate of roots decreased more than that of shoots (by 6–27% for shoots, by 15–74% for roots), and plant growth was reduced proportionally as the water level was increased. Light-saturated net photosynthesis was reduced by 70–80% for the two most severe waterlogging treatments, but was little affected for plants in soil waterlogged at 200 mm below the surface. The number of adventitious roots formed per stem in plants grown in waterlogged soil increased up to 1.5 times, but the number of tillers per plant was reduced by 24–62%. The adventitious roots only penetrated 85–116 mm below the water level in all waterlogging treatments. Adventitious root porosity was enhanced up to 10-fold for plants grown in waterlogged soil, depending on water level and position along the roots. Porosity also increased in basal zones of roots above the water level when the younger tissues had penetrated the waterlogged zone. Fourteen days after draining the pots, growth rates of plants where the soil had been waterlogged at 200 mm below the surface had recovered, while those of plants in the more severely waterlogged treatments had only partially recovered. These findings show that the depth of waterlogging has a large impact on the response of wheat both during and after a waterlogging event so that assessment of recovery is essential in evaluating waterlogging tolerance in crops.

Tolerance of submerged germinating rice to 50–200 mM NaCl in aerated solution

Publisher: Wiley

Date: 15-03-2013

DOI: 10.1111/PPL.12029

Abstract: This paper concerns tolerance to 50-200 mM NaCl of submerged rice (Oryza sativa cv. Amaroo) during germination and the first 138-186 h of development in aerated solution. Rice was able to germinate and the seedlings even tolerated exposure to 200 mM NaCl, albeit with severe growth restrictions. After return to 0.3 mM NaCl, growth increased, indicating that even at 200 mM NaCl there was no irreparable injury. Osmotic adjustment was achieved by using Na⁺ and Cl⁻ as the major osmotica. At 200 mM NaCl commenced at sowing, the shoot Na⁺ and Cl⁻ concentrations between 50-110 h were about 210 and 260 mM, respectively, i.e. above the external concentration. Thus, there was a high tissue tolerance to NaCl. The internal concentrations declined subsequently, concurrent with a decline in growth. At 50-200 mM NaCl, the contributions from ions to πsap were 81-92% in roots and 62-74% in shoots. The assessed turgor pressures at 200 mM NaCl were 0.33 MPa in shoots and 0.15 MPa in roots, compared to 0.62 and 0.43 MPa at 0.3 mM NaCl. In the General Discussion section, we compare the different responses of submerged seedlings to the responses of transpiring rice plants, reported in the literature, and suggest that the submerged system is useful to evaluate effects of NaCl on turgor pressure and particularly to establish whether there are specific effects of Na⁺ and Cl⁻ in tissues.

Dryland field validation of genotypic variation in salt tolerance of chickpea (Cicer arietinum L.) determined under controlled conditions

Publisher: Elsevier BV

Date: 02-2022

DOI: 10.1016/J.FCR.2021.108392

Waterlogging affects the growth, development of tillers, and yield of wheat through a severe, but transient, N deficiency

Publisher: CSIRO Publishing

Date: 2009

DOI: 10.1071/CP08440

Abstract: Tiller production and survival are suppressed on soils prone to waterlogging. The tiller production and growth of wheat (Triticum aestivum cv. Wyalkatchem) was investigated in a glasshouse experiment during and after a transient waterlogging to examine its effect on grain yield. Wheat plants received either a high or low nitrogen (N) application at sowing and were waterlogged at 22 days after sowing for 14 days. Plants received a second either high or low N application after waterlogging was released. Waterlogging induced a transient N deficiency. The N concentration of the youngest expanded leaf on the mainstem and tillers declined markedly during waterlogging, but its recovery 14 days after the waterlogging was ended was independent of treatment, reaching a greater than the critical minimum concentration of 3.5%. The growth of primary tillers 1 and 2 was severely inhibited by waterlogging while the exsertion of new tillers was delayed by 9 days. Shoot dry weight of the waterlogged plants at final harvest was reduced by 37% compared with the non-waterlogged plants. During the recovery period, the waterlogged plants produced higher order tillers that produced late ears. As a result, the number of ears per plant was similar in plants in continuously drained or previously waterlogged soil. Waterlogging reduced the number of grains per ear on the mainstem and tillers, and consequently grain yield by 32%. High N application after waterlogging increased grain yield by ~20%, but high N applied at sowing had no effect on yield. This suggests that N application after waterlogging can reduce the detrimental effect of waterlogging on grain yields in areas prone to waterlogging.

Salinity and waterlogging as constraints to saltland pasture production: A review

Publisher: Elsevier BV

Date: 02-2009

DOI: 10.1016/J.AGEE.2008.10.013

Comparisons of annual pasture legumes in growth, ion regulation and root porosity demonstrate that Melilotus siculus has exceptional tolerance to combinations of salinity and waterlogging

Publisher: Elsevier BV

Date: 04-2012

DOI: 10.1016/J.ENVEXPBOT.2011.11.020

Soil properties and turf growth on a sandy soil amended with fly ash

Publisher: Springer Science and Business Media LLC

Date: 09-2003

DOI: 10.1023/A:1026203113588

Lateral roots, in addition to adventitious roots, form a barrier to radial oxygen loss in Zea nicaraguensis and a chromosome segment introgression line in maize

Publisher: Wiley

Date: 21-02-2020

DOI: 10.1111/NPH.16452

Abstract: Plants typically respond to waterlogging by producing new adventitious roots with aerenchyma and many wetland plants form a root barrier to radial O 2 loss (ROL), but it was not known if this was also the case for lateral roots. We tested the hypothesis that lateral roots arising from adventitious roots can form a ROL barrier, using root‐sleeving electrodes and O 2 microsensors to assess ROL of Zea nicaraguensis , the maize ( Zea mays ssp. mays ) introgression line with a locus for ROL barrier formation (introgression line (IL) #468) from Z. nicaraguensis and a maize inbred line (Mi29). Lateral roots of Z. nicaraguensis and IL #468 both formed a ROL barrier under stagnant, deoxygenated conditions, whereas Mi29 did not. Lateral roots of Z. nicaraguensis had higher tissue O 2 status than for IL #468 and Mi29. The ROL barrier was visible as suberin in the root hypodermis/exodermis. Modelling showed that laterals roots can grow to a maximum length of 74 mm with a ROL barrier, but only to 33 mm without a barrier. Presence of a ROL barrier in lateral roots requires reconsideration of the role of these roots as sites of O 2 loss, which for some species now appears to be less than hitherto thought.

Effectiveness of cultural thatch-mat controls for young and mature Kikuyu turfgrass

Publisher: Wiley

Date: 2009

DOI: 10.2134/AGRONJ2008.0180

Uptake of inorganic phosphorus by the aquatic plant Isoetes australis inhabiting oligotrophic vernal rock pools

Publisher: Elsevier BV

Date: 02-2017

DOI: 10.1016/J.AQUABOT.2017.01.004

Sodium chloride toxicity and the cellular basis of salt tolerance in halophytes

Publisher: Oxford University Press (OUP)

Date: 12-2015

DOI: 10.1093/AOB/MCU217

Oxygen dynamics in submerged rice (Oryza sativa)

Publisher: Wiley

Date: 31-01-2008

DOI: 10.1111/J.1469-8137.2007.02364.X

Abstract: Complete submergence of plants prevents direct O(2) and CO(2) exchange with air. Underwater photosynthesis can result in marked diurnal changes in O(2) supply to submerged plants. Dynamics in pO(2) had not been measured directly for submerged rice (Oryza sativa), but in an earlier study, radial O(2) loss from roots showed an initial peak following shoot illumination. O(2) dynamics in shoots and roots of submerged rice were monitored during light and dark periods, using O(2) microelectrodes. Tissue sugar concentrations were also measured. On illumination of shoots of submerged rice, pO(2) increased rapidly and then declined slightly to a new quasi-steady state. An initial peak was evident first in the shoots and then in the roots, and was still observed when 20 mol m(-3) glucose was added to the medium to ensure substrate supply in roots. At the new quasi-steady state following illumination, sheath pO(2) was one order of magnitude higher than in darkness, enhancing also pO(2) in roots. The initial peak in pO(2) following illumination of submerged rice was likely to result from high initial rates of net photosynthesis, fuelled by CO(2) accumulated during the dark period. Nevertheless, since sugars decline with time in submerged rice, substrate limitation of respiration could also contribute to morning peaks in pO(2) after longer periods of submergence.

Contrasting submergence tolerance in two species of stem-succulent halophytes is not determined by differences in stem internal oxygen dynamics

Publisher: Oxford University Press (OUP)

Date: 02-12-2015

DOI: 10.1093/AOB/MCU216

Transfer of the barrier to radial oxygen loss in roots of Hordeum marinum to wheat (Triticum aestivum): evaluation of four H. marinum–wheat amphiploids

Publisher: Wiley

Date: 03-11-2010

DOI: 10.1111/J.1469-8137.2010.03519.X

Abstract: • Wide hybridization of waterlogging-tolerant Hordeum marinum with wheat (Triticum aestivum) to produce an hiploid might be one approach to improve waterlogging tolerance in wheat. • Growth, root aerenchyma and porosity, and radial oxygen loss (ROL) along roots were measured in four H. marinum-wheat hiploids and their parents (four accessions of H. marinum and Chinese Spring wheat) in aerated or stagnant nutrient solution. A soil experiment was also conducted. • Hordeum marinum maintained shoot dry mass in stagnant nutrient solution, whereas the growth of wheat was markedly reduced (40% of aerated control). Two of the four hiploids were more tolerant than wheat (shoot dry masses of 59-72% of aerated controls). The porosity of adventitious roots when in stagnant solution was higher in H. marinum (19-25%) and the four hiploids (20-24%) than in wheat (16%). In stagnant solution, adventitious roots of H. marinum formed a strong ROL barrier in basal zones, whereas, in wheat, the barrier was weak. Two hiploids formed a strong ROL barrier and two formed a moderate barrier when in stagnant solution. • This study demonstrates the transfer of higher root porosity and a barrier to ROL from H. marinum to wheat through wide hybridization and the production of H. marinum-wheat hiploids.

Novel Salinity Tolerance Loci in Chickpea Identified in Glasshouse and Field Environments

Publisher: Frontiers Media SA

Date: 28-04-2021

DOI: 10.3389/FPLS.2021.667910

Abstract: A better understanding of the genetics of salinity tolerance in chickpea would enable breeding of salt tolerant varieties, offering potential to expand chickpea production to marginal, salinity-affected areas. A Recombinant Inbred Line population was developed using accelerated-Single Seed Descent of progeny from a cross between two chickpea varieties, Rupali (salt-sensitive) and Genesis836 (salt-tolerant). The population was screened for salinity tolerance using high-throughput image-based phenotyping in the glasshouse, in hydroponics, and across 2 years of field trials at Merredin, Western Australia. A genetic map was constructed from 628 unique in-silico DArT and SNP markers, spanning 963.5 cM. Markers linked to two flowering loci identified on linkage groups CaLG03 and CaLG05 were used as cofactors during genetic analysis to remove the confounding effects of flowering on salinity response. Forty-two QTL were linked to growth rate, yield, and yield component traits under both control and saline conditions, and leaf tissue ion accumulation under salt stress. Residuals from regressions fitting best linear unbiased predictions from saline conditions onto best linear unbiased predictions from control conditions provided a measure of salinity tolerance per se , independent of yield potential. Six QTL on CaLG04, CaLG05, and CaLG06 were associated with tolerance per se . In total, 21 QTL mapped to two distinct regions on CaLG04. The first distinct region controlled the number of filled pods, leaf necrosis, seed number, and seed yield specifically under salinity, and co-located with four QTL linked to salt tolerance per se . The second distinct region controlled 100-seed weight and growth-related traits, independent of salinity treatment. Positional cloning of the salinity tolerance-specific loci on CaLG04, CaLG05, and CaLG06 will improve our understanding of the key determinants of salinity tolerance in chickpea.

Does anoxia tolerance involve altering the energy currency towards PPi?

Publisher: Elsevier BV

Date: 05-2008

DOI: 10.1016/J.TPLANTS.2008.02.007

Abstract: Oxygen deficit is an important abiotic stress influencing plants, because this condition results in an 'energy crisis'. Most species only survive short periods of anoxia, but several wetland species tolerate prolonged anoxia. Transcriptomic and proteomic studies, using anoxia-tolerant rice and anoxia-intolerant Arabidopsis, have provided evidence for the selective adoption of pyrophosphate (PPi) over ATP as high-energy donor molecules, which may contribute to anoxia tolerance. The use of PPi in some tolerant plant species is similar to that observed in many anaerobic prokaryotes. Investigations are being performed to better understand the origin and regulation of reversible PPi-dependent glycolytic enzymes such as cytosolic pyruvate phosphate dikinase, as well as PPi-consuming enzymes, which are engaged during the anoxic energy crisis. This will be crucial in unraveling this currency switch and its contribution to anoxia tolerance.

In situ O-2 dynamics in submerged Isoetes australis: varied leaf gas permeability influences underwater photosynthesis and internal O-2

Publisher: Oxford University Press (OUP)

Date: 08-2011

DOI: 10.1093/JXB/ERR193

Crassulacean acid metabolism enhances underwater photosynthesis and diminishes photorespiration in the aquatic plant Isoetes australis

Publisher: Wiley

Date: 09-11-2010

DOI: 10.1111/J.1469-8137.2010.03522.X

Abstract: • Underwater photosynthesis by aquatic plants is often limited by low availability of CO(2), and photorespiration can be high. Some aquatic plants utilize crassulacean acid metabolism (CAM) photosynthesis. The benefits of CAM for increased underwater photosynthesis and suppression of photorespiration were evaluated for Isoetes australis, a submerged plant that inhabits shallow temporary rock pools. • Leaves high or low in malate were evaluated for underwater net photosynthesis and apparent photorespiration at a range of CO(2) and O(2) concentrations. • CAM activity was indicated by 9.7-fold higher leaf malate at dawn, compared with at dusk, and also by changes in the titratable acidity (μmol H(+) equivalents) of leaves. Leaves high in malate showed not only higher underwater net photosynthesis at low external CO(2) concentrations but also lower apparent photorespiration. Suppression by CAM of apparent photorespiration was evident at a range of O(2) concentrations, including values below air equilibrium. At a high O(2) concentration of 2.2-fold the atmospheric equilibrium concentration, net photosynthesis was reduced substantially and, although it remained positive in leaves containing high malate concentrations, it became negative in those low in malate. • CAM in aquatic plants enables higher rates of underwater net photosynthesis over large O(2) and CO(2) concentration ranges in floodwaters, via increased CO(2) fixation and suppression of photorespiration.

Root aeration in rice (Oryza sativa): evaluation of oxygen, carbon dioxide, and ethylene as possible regulators of root acclimatizations

Publisher: Wiley

Date: 07-04-2006

DOI: 10.1111/J.1469-8137.2006.01725.X

Abstract: Adventitious roots of rice (Oryza sativa) acclimatize to root-zone O(2) deficiency by increasing porosity, and induction of a barrier to radial O(2) loss (ROL) in basal zones, to enhance longitudinal O(2) diffusion towards the root tip. Changes in root-zone gas composition that might induce these acclimatizations, namely low O(2), elevated ethylene, ethylene-low O(2) interactions, and high CO(2), were evaluated in hydroponic experiments. Neither low O(2) (0 or 0.028 mol m(-3) O(2)), ethylene (0.2 or 2.0 microl l(-1)), or combinations of these treatments, induced the barrier to ROL. This lack of induction of the barrier to ROL was despite a positive response of aerenchyma formation to low O(2) and elevated ethylene. Carbon dioxide at 10 kPa had no effect on root porosity, the barrier to ROL, or on growth. Our findings that ethylene does not induce the barrier to ROL in roots of rice, even though it can enhance aerenchyma formation, shows that these two acclimatizations for improved root aeration are differentially regulated.

Tolerance of Hordeum marinum accessions to O2 deficiency, salinity and these stresses combined

Publisher: Oxford University Press (OUP)

Date: 14-08-2008

DOI: 10.1093/AOB/MCN142

Drought tolerances of three stem-succulent halophyte species of an inland semiarid salt lake system

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/FP14108

Abstract: Succulent halophytes of the genus Tecticornia are dominant in salt marshes of inland lakes of Australia. We assessed the drought responses of a C4 species, Tecticornia indica subsp. bidens (Nees) K.A.Sheph. & Paul G.Wilson, and two C3 species, Tecticornia auriculata Paul G.Wilson (K.A.Sheph. & Paul G.Wilson) and Tecticornia medusa (K.A.Sheph. & S.J.van Leeuwen) that occur in the Fortescue Marsh, north-west Australia. In a glasshouse experiment, the three species were grown in idually and in different combinations, with varying number of plants per pot to achieve comparable dry-down rates among pots. Prior to the imposition of drought (by withholding water) the three species showed differences in dry mass and physiological variables. As the soil dried out, the three species showed similar reductions of transpiration, osmotic potential and photochemical efficiency. Shoot growth was depressed more than root growth. Tissue water loss from portions of the succulent shoots accounted for ~30% of transpiration during severe drought stress. There was no osmotic adjustment. Shoot tissue concentrations of Na+ and Cl– tended to increase during drought, and those of K+ decreased however, these changes were not always statistically significant. Chlorophyll concentration decreased but betacyanin concentration increased. Despite occupying distinct positions in a water and salinity gradient, the three Tecticornia species had remarkably similar responses to soil water deficit.

Short‐term waterlogging has long‐term effects on the growth and physiology of wheat

Publisher: Wiley

Date: 02-2002

DOI: 10.1046/J.0028-646X.2001.00318.X

Anoxia tolerance in rice seedlings: exogenous glucose improves growth of an anoxia-'intolerant', but not of a 'tolerant' genotype

Publisher: Oxford University Press (OUP)

Date: 10-2003

DOI: 10.1093/JXB/ERG252

Mechanisms of waterlogging tolerance in wheat - a review of root and shoot physiology

Publisher: Wiley

Date: 07-02-2016

DOI: 10.1111/PCE.12676

Abstract: We review the detrimental effects of waterlogging on physiology, growth and yield of wheat. We highlight traits contributing to waterlogging tolerance and genetic ersity in wheat. Death of seminal roots and restriction of adventitious root length due to O2 deficiency result in low root:shoot ratio. Genotypes differ in seminal root anoxia tolerance, but mechanisms remain to be established ethanol production rates do not explain anoxia tolerance. Root tip survival is short-term, and thereafter, seminal root re-growth upon re-aeration is limited. Genotypes differ in adventitious root numbers and in aerenchyma formation within these roots, resulting in varying waterlogging tolerances. Root extension is restricted by capacity for internal O2 movement to the apex. Sub-optimal O2 restricts root N uptake and translocation to the shoots, with N deficiency causing reduced shoot growth and grain yield. Although photosynthesis declines, sugars typically accumulate in shoots of waterlogged plants. Mn or Fe toxicity might occur in shoots of wheat on strongly acidic soils, but probably not more widely. Future breeding for waterlogging tolerance should focus on root internal aeration and better N-use efficiency exploiting the genetic ersity in wheat for these and other traits should enable improvement of waterlogging tolerance.

Responses by Coleoptiles of Intact Rice Seedlings to Anoxia: K+ Net Uptake from the External Solution and Translocation from the Caryopses

Publisher: Oxford University Press (OUP)

Date: 2003

DOI: 10.1093/AOB/MCF122

Abstract: This study evaluated the effects of anoxia on K(+) uptake and translocation in 3-4-d-old, intact, rice seedlings (Oryza sativa L. cv. Calrose). Rates of net K(+) uptake from the medium over 24 h by coleoptiles of anoxic seedlings were inhibited by 83-91 %, when compared with rates in aerated seedlings. Similar uptake rates, and degree of inhibition due to anoxia, were found for Rb(+) when supplied over 1.5-2 h, starting 22 h after imposing anoxia. The Rb(+) uptake indicated that intact coleoptiles take up ions directly from the external solution. Monovalent cation (K(+) and Rb(+)) net uptake from the solution was inhibited by anoxia to the same degree for the coleoptiles of intact seedlings and for coleoptiles excised, 'aged', and supplied with exogenous glucose. Transport of endogenous K(+) from caryopses to coleoptiles was inhibited less by anoxia than net K(+) uptake from the solution, the inhibition being 55 % rather than 87 %. Despite these inhibitions, osmotic pressures of sap (pi(sap)) expressed from coleoptiles of seedlings exposed to 48 h of anoxia, with or without exogenous K(+), were 0.66 +/- 0.03 MPa however, the contributions of K(+) to pi(sap) were 23 and 16 %, respectively. After 24 h of anoxia, the K(+) concentrations in the basal 10 mm of the coleoptiles of seedlings with or without exogenous K(+), were similar to those in aerated seedlings with exogenous K(+). In contrast, K(+) concentrations had decreased in aerated seedlings without exogenous K(+), presumably due to 'dilution' by growth fresh weight gains of the coleoptile being 3.6- to 4.7-fold greater in aerated than in anoxic seedlings. Deposition rates of K(+) along the axes of the coleoptiles were calculated for the anoxic seedlings only, for which we assessed the elongation zone to be only the basal 4 mm. K(+) deposition in the basal 6 mm was similar for seedlings with or without exogenous K(+), at 0.6-0.87 micro mol g(-1) f. wt h(-1). Deposition rates in zones above 6 mm from the base were greater for seedlings with, than without, exogenous K(+) the latter were sometimes negative. We conclude that for the coleoptiles of rice seedlings, anoxia inhibits net K(+) uptake from the external solution to a much larger extent than K(+) translocation from the caryopses. Furthermore, K(+) concentrations in the elongation zone of the coleoptiles of anoxic seedlings were maintained to a remarkable degree, contributing to maintenance of pi(sap) in cells of these elongating tissues.

Rice leaf hydrophobicity and gas films are conferred by a wax synthesis gene (LGF1) and contribute to flood tolerance

Publisher: Wiley

Date: 02-03-2018

DOI: 10.1111/NPH.15070

Abstract: Floods impede gas (O

Turfgrass (Cynodon dactylon L.) sod production on sandy soils: II. Effects of irrigation and fertiliser regimes on N leaching

Publisher: Springer Science and Business Media LLC

Date: 06-2006

DOI: 10.1007/S11104-006-0036-X

Salinity and waterlogging tolerance amongst accessions of messina (Melilotus siculus)

Publisher: CSIRO Publishing

Date: 2009

DOI: 10.1071/CP10270

Abstract: Melilotus siculus (common name messina) has shown potential as a productive annual forage legume in saline and waterlogged areas in temperate Australia. The salt and waterlogging tolerances of 30 M. siculus accessions were evaluated at germination and as established plants. Many accessions germinated at 240 mm NaCl, but germination was % at 320 mm NaCl. In vegetative plants, accessions differed in the degree of growth reduction at 300 mm NaCl, with some producing %, but others %, of non-saline controls. A negative relationship (r = 0.47, P 0.001) was found between dry weight under non-saline conditions and relative salt tolerance (i.e. salt-treated as % of controls). Concentrations of Cl– and Na+ in shoots of all accessions increased significantly with increasing NaCl in the medium, although these differed among accessions. No relationships were found between shoot Cl–, Na+, or K+ concentrations and relative salt tolerance at 300 mm NaCl, whereas net K+ : Na+ selectivity to shoots was positively correlated with relative salt tolerance (r = 0.30, P = 0.1). All accessions showed good tolerance to stagnant, O2-deficient conditions in the root medium, and shoot growth was not reduced by % in any accession. Root porosity (% gas volume/root volume) in both the main and lateral roots increased in all accessions when in stagnant medium, but accessions differed in root porosity. Lateral root porosity was not, however, correlated with either shoot dry weight or root dry weight in stagnant conditions. No single accession of M. siculus had the highest tolerance to saline conditions both at germination and the vegetative stage, but some accessions (e.g. SA 40002 and SA 40004) performed consistently well under saline and waterlogged conditions. Further research and selection is warranted on these accessions with the aim to release a cultivar.

Diversity in root aeration traits associated with waterlogging tolerance in the genus Hordeum

Publisher: CSIRO Publishing

Date: 2003

DOI: 10.1071/FP03058

Abstract: Growth, root aerenchyma, and profiles of radial O2 loss (ROL) along adventitious roots were evaluated in 35 'wild' Hordeum accessions and cultivated barley (H. vulgare L. ssp. vulgare) when grown in stagnant nutrient solution (deoxygenated and containing 0.1% agar). When grown in stagnant solution, accessions from wetland and 'intermediate' habitats were superior, compared with accessions from non-wetland habitats, in maintaining relative growth rate, tillering, and adventitious root mass. Constitutive aerenchyma formation in adventitious roots was ≥�10% in 22 accessions (cf. H. vulgare at 2%). When grown in stagnant solution, aerenchyma was ≥� 20% in the adventitious roots of 14 accessions (cf. H. vulgare at 12%). Variation among the accessions in the volume of aerenchyma formed when grown in aerated or stagnant solution was not determined by the waterlogging regime of the species' natural habitat. However, the genus Hordeum comprises four genomes and when grown in stagnant solution accessions with the X genome formed, on average, 22% aerenchyma in adventitious roots (50 mm behind apex), whereas those with the H genome averaged 19%, and those with the Y or I genomes averaged 16 and 15%, respectively. Sixteen accessions formed a barrier to ROL in the basal region of adventitious roots when grown in stagnant solution. The formation of a barrier to radial O2 loss was predominant in accessions from wet habitats, and absent in accessions from non-wetland habitats. In addition, this trait was only present in accessions with the X or H genomes. The combination of aerenchyma and a barrier to ROL enhances the longitudinal diffusion of O2 within roots towards the apex. The possibility of a link between having a barrier to ROL and the X or H genomes in Hordeum species might, in future studies, enable a genetic analysis of this important trait.

Wheat genotypes show contrasting abilities to recover from anoxia in spite of similar anoxic carbohydrate metabolism

Publisher: Elsevier BV

Date: 12-2007

DOI: 10.1016/J.JPLPH.2007.01.007

Abstract: Physiological and metabolic responses to anoxia and reaeration were compared for 4-7-day-old seedlings of 11 genotypes of wheat (Triticum aestivum) with reputed differences in waterlogging tolerance. Genotypes differed in seminal root elongation, and recovery of root tissue K(+) concentration, during reaeration following 72 h anoxia. Post-anoxic recovery ranged from complete (100% retention of seminal root elongation potential) to almost nil (death of all seminal root apices and inability to recover K(+) concentration). The anoxia tolerance ranking of the genotypes based on these parameters corresponded with that of their reputed waterlogging tolerance, but with some exceptions. However, the differences in anoxia tolerance of the seedlings could not be explained by differences in capacity for ethanol production. A decreased ability to utilise seed starch reserves under anoxia, due to inadequate levels of alpha-amylase activity at the time anoxia was imposed, was apparent in all genotypes.

Ion transport in seminal and adventitious roots of cereals during O2 deficiency

Publisher: Oxford University Press (OUP)

Date: 16-09-2010

DOI: 10.1093/JXB/ERQ271

Abstract: O(2) deficiency during soil waterlogging inhibits respiration in roots, resulting in severe energy deficits. Decreased root-to-shoot ratio and suboptimal functioning of the roots, result in nutrient deficiencies in the shoots. In N(2)-flushed nutrient solutions, wheat seminal roots cease growth, while newly formed adventitious roots develop aerenchyma, and grow, albeit to a restricted length. When reliant on an internal O(2) supply from the shoot, nutrient uptake by adventitious roots was inhibited less than in seminal roots. Epidermal and cortical cells are likely to receive sufficient O(2) for oxidative phosphorylation and ion transport. By contrast, stelar hypoxia-anoxia can develop so that H(+)-ATPases in the xylem parenchyma would be inhibited the diminished H(+) gradients and depolarized membranes inhibit secondary energy-dependent ion transport and channel conductances. Thus, the presence of two transport steps, one in the epidermis and cortex to accumulate ions from the solution and another in the stele to load ions into the xylem, is important for understanding the inhibitory effects of root zone hypoxia on nutrient acquisition and xylem transport, as well as the regulation of delivery to the shoots of unwanted ions, such as Na(+). Improvement of waterlogging tolerance in wheat will require an increased capacity for root growth, and more efficient root functioning, when in anaerobic media.

Life at the boundary: photosynthesis at the soil–fluid interface. A synthesis focusing on mosses: Table 1.

Publisher: Oxford University Press (OUP)

Date: 02-02-2016

DOI: 10.1093/JXB/ERW012

Abstract: Mosses are among the earliest branching embryophytes and probably originated not later than the early Ordovician when atmospheric CO2 was higher and O2 was lower than today. The C3 biochemistry and physiology of their photosynthesis suggests, by analogy with tracheophytes, that growth of extant bryophytes in high CO2 approximating Ordovician values would increase the growth rate. This occurs for many mosses, including Physcomitrella patens in suspension culture, although recently published transcriptomic data on this species at high CO2 and present-day CO2 show down-regulation of the transcription of several genes related to photosynthesis. It would be useful if transcriptomic (and proteomic) data comparing growth conditions are linked to measurements of growth and physiology on the same, or parallel, cultures. Mosses (like later-originating embryophytes) have been subject to changes in bulk atmospheric CO2 and O2 throughout their existence, with evidence, albeit limited, for positive selection of moss Rubisco. Extant mosses are subject to a large range of CO2 and O2 concentrations in their immediate environments, especially aquatic mosses, and mosses are particularly influenced by CO2 generated by, and O2 consumed by, soil chemoorganotrophy from organic C produced by tracheophytes (if present) and bryophytes.

Ameliorating water repellency under turfgrass of contrasting soil organic matter content: Effect of wetting agent formulation and application frequency

Publisher: Elsevier BV

Date: 11-2011

DOI: 10.1016/J.AGWAT.2011.08.009

Irrigation and fertilizer strategies for minimising nitrogen leaching from turfgrass

Publisher: Elsevier BV

Date: 02-2006

DOI: 10.1016/J.AGWAT.2005.07.011

Revealing the roles of GORK channels and NADPH oxidase in acclimation to hypoxia in Arabidopsis

Publisher: Oxford University Press (OUP)

Date: 19-10-2016

DOI: 10.1093/JXB/ERW378

Large number of flowers and tertiary branches, and higher reproductive success increase yields under salt stress in chickpea

Publisher: Elsevier BV

Date: 08-2012

DOI: 10.1016/J.EJA.2012.03.008

Spatial patterns of radial oxygen loss and nitrate net flux along adventitious roots of rice raised in aerated or stagnant solution

Publisher: CSIRO Publishing

Date: 2002

DOI: 10.1071/FP02081

Abstract: Roots of rice (Oryza sativa L.) grown in stagnant de-oxygenated solution contain a 'tight' barrier to radial oxygen loss (ROL) in basal zones, whereas roots of plants grown in aerated solution do not. It is generally accepted that the barrier to ROL involves anatomical modifications in the apoplast of cell layers exterior to the aerenchyma. A possible drawback of this adaptation is a reduced capacity for nutrient uptake. Whether or not induction of a barrier to ROL influences the capacity of adventitious roots of rice to take up NO3– was determined in the present study, using NO3–-selective microelectrodes. When transferred into O2-free root medium, ROL from positions at 30–50 mm behind the tip of adventitious roots of plants raised in stagnant solution was only 4–6% of the rate from roots of plants raised in aerated solution, indicating the barrier to ROL was induced by growth in stagnant solution. For plants transferred into aerobic nutrient solution containing 0.1 mM NO3–, net NO3– uptake by these root zones, with or without a barrier to ROL, was the same. It is concluded that induction of a barrier to ROL had no effect on the capacity of adventitious roots of rice to take up NO3– from aerobic solution.

The genetics of vigour-related traits in chickpea (Cicer arietinum L.): insights from genomic data

Publisher: Springer Science and Business Media LLC

Date: 13-10-2021

DOI: 10.1007/S00122-021-03954-4

Abstract: QTL controlling vigour and related traits were identified in a chickpea RIL population and validated in erse sets of germplasm. Robust KASP markers were developed for marker-assisted selection. To understand the genetic constitution of vigour in chickpea (Cicer arietinum L.), genomic data from a bi-parental population and multiple ersity panels were used to identify QTL, sequence-level haplotypes and genetic markers associated with vigour-related traits in Australian environments. Using 182 Recombinant Inbred Lines (RILs) derived from a cross between two desi varieties, Rupali and Genesis836, vigour QTL independent of flowering time were identified on chromosomes (Ca) 1, 3 and 4 with genotypic variance explained (GVE) ranging from 7.1 to 28.8%. Haplotype analysis, association analysis and graphical genotyping of whole-genome re-sequencing data of two ersity panels consisting of Australian and Indian genotypes and an ICRISAT Chickpea Reference Set revealed a deletion in the FTa1-FTa2-FTc gene cluster of Ca3 significantly associated with vigour and flowering time. Across the RIL population and ersity panels, the impact of the deletion was consistent for vigour but not flowering time. Vigour-related QTL on Ca4 co-located with a QTL for seed size in Rupali/Genesis836 (GVE = 61.3%). Using SNPs from this region, we developed and validated gene-based KASP markers across different panels. Two markers were developed for a gene on Ca1, myo -inositol monophosphatase (CaIMP), previously proposed to control seed size, seed germination and seedling growth in chickpea. While associated with vigour in the ersity panels, neither the markers nor broader haplotype linked to CaIMP was polymorphic in Rupali/Genesis836. Importantly, vigour appears to be controlled by different sets of QTL across time and with components which are independent from phenology.

Visualisation by high resolution synchrotron X-ray phase contrast micro-tomography of gas films on submerged superhydrophobic leaves

Publisher: Elsevier BV

Date: 10-2014

DOI: 10.1016/J.JSB.2014.08.003

Abstract: Floods can completely submerge terrestrial plants but some wetland species can sustain O2 and CO2 exchange with the environment via gas films forming on superhydrophobic leaf surfaces. We used high resolution synchrotron X-ray phase contrast micro-tomography in a novel approach to visualise gas films on submerged leaves of common cordgrass (Spartina anglica). 3D tomograms enabled a hitherto unmatched level of detail regarding the micro-topography of leaf gas films. Gas films formed only on the superhydrophobic adaxial leaf side (water droplet contact angle, Φ=162°) but not on the abaxial side (Φ=135°). The adaxial side of the leaves of common cordgrass is plicate with a longitudinal system of parallel grooves and ridges and the vast majority of the gas film volume was found in large ∼180μm deep elongated triangular volumes in the grooves and these volumes were connected to each neighbouring groove via a fine network of gas tubules (∼1.7μm diameter) across the ridges. In addition to the gas film retained on the leaf exterior, the X-ray phase contrast micro-tomography also successfully distinguished gas spaces internally in the leaf tissues, and the tissue porosity (gas volume per unit tissue volume) ranged from 6.3% to 20.3% in tip and base leaf segments, respectively. We conclude that X-ray phase contrast micro-tomography is a powerful tool to obtain quantitative data of exterior gas features on biological s les because of the significant difference in electron density between air, biological tissues and water.

Response to non-uniform salinity in the root zone of the halophyte Atriplex nummularia: growth, photosynthesis, water relations and tissue ion concentrations

Publisher: Oxford University Press (OUP)

Date: 25-06-2009

DOI: 10.1093/AOB/MCP151

Effects on growth and development of individual chromosomes from slow-growing Lophopyrum elongatum Love when incorporated in bread wheat (Triticum aestivum L.)

Publisher: Oxford University Press (OUP)

Date: 08-2001

DOI: 10.1006/ANBO.2001.1444

Osmotic adjustment and energy limitations to plant growth in saline soil

Publisher: Wiley

Date: 21-05-2020

DOI: 10.1111/NPH.15862

Abstract: Plant roots must exclude almost all of the Na

A lack of aerenchyma and high rates of radial oxygen loss from the root base contribute to the waterlogging intolerance of Brassica napus

Publisher: CSIRO Publishing

Date: 1999

DOI: 10.1071/PP98086

Abstract: The morphology and physiology of the response of two cultivars of Brassica napus to an anaerobic root medium was investigated. The cultivars Chikuzen and Topas showed a large reduction in growth rate when their roots were exposed to a de-oxygenated stagnant nutrient solution containing 0.1% w/v agar. Older seedlings (11 d old) were more sensitive to stagnant agar, expressed as biomass accumulation, than younger ones (5 d old). Brassica napus was characterized by a constitutively low root porosity (3–5%), typical for plant species with a low tolerance to waterlogging. A hypoxia pre- treatment (16 h 2.25% O2) before exposure to de-oxygenated stagnant agar had no effect on the final number or length of lateral roots and adventitious roots. Brassica napus cv. Chikuzen is characterized by radial oxygen loss being most at the basal portion of the root, when a strong oxygen sink surrounds the root. Oxygen profiles through laterals of Brassica napus cv. Chikuzen show a typical pattern with low oxygen concentrations in the stele and somewhat higher levels in the cortex. Despite the continuum of intercellular air spaces in the root cortical tissue the lack of aerenchyma and therefore low rates of internal oxygen diffusion restricts root growth in anaerobic media and presumably contributes to the sensitivity of Brassica napus to waterlogging.

Spatio-temporal relief from hypoxia and production of reactive oxygen species during bud burst in grapevine (Vitis vinifera)

Publisher: Oxford University Press (OUP)

Date: 09-2015

DOI: 10.1093/AOB/MCV123

Flooding tolerance: suites of plant traits in variable environments

Publisher: CSIRO Publishing

Date: 2009

DOI: 10.1071/FP09144

Abstract: Flooding regimes of different depths and durations impose selection pressures for various traits in terrestrial wetland plants. Suites of adaptive traits for different flooding stresses, such as soil waterlogging (short or long duration) and full submergence (short or long duration – shallow or deep), are reviewed. Synergies occur amongst traits for improved internal aeration, and those for anoxia tolerance and recovery, both for roots during soil waterlogging and shoots during submergence. Submergence tolerance of terrestrial species has recently been classified as either the Low Oxygen Quiescence Syndrome (LOQS) or the Low Oxygen Escape Syndrome (LOES), with advantages, respectively, in short duration or long duration (shallow) flood-prone environments. A major feature of species with the LOQS is that shoots do not elongate upon submergence, whereas those with the LOES show rapid shoot extension. In addition, plants faced with long duration deep submergence can demonstrate aspects of both syndromes shoots do not elongate, but these are not quiescent, as new aquatic-type leaves are formed. Enhanced entries of O2 and CO2 from floodwaters into acclimated leaves, minimises O2 deprivation and improves underwater photosynthesis, respectively. Evolution of ‘suites of traits’ are evident in wild wetland species and in rice, adapted to particular flooding regimes.

Plant tolerance of flooding stress – recent advances

Publisher: Wiley

Date: 22-08-2014

DOI: 10.1111/PCE.12420

Salt accumulation and depletion in the root-zone of the halophyte Atriplex nummularia Lindl.: influence of salinity, leaf area and plant water use

Publisher: Springer Science and Business Media LLC

Date: 16-05-2014

DOI: 10.1007/S11104-014-2148-Z

Hordeum marinum-wheat amphiploids maintain higher leaf K+:Na+ and suffer less leaf injury than wheat parents in saline conditions

Publisher: Springer Science and Business Media LLC

Date: 19-08-2011

DOI: 10.1007/S11104-011-0934-4

The mechanism of improved aeration due to gas films on leaves of submerged rice

Publisher: Wiley

Date: 20-03-2014

DOI: 10.1111/PCE.12300

Abstract: Some terrestrial wetland plants, such as rice, have super-hydrophobic leaf surfaces which retain a gas film when submerged. O2 movement through the diffusive boundary layer (DBL) of floodwater, gas film and stomata into leaf mesophyll was explored by means of a reaction-diffusion model that was solved in a three-dimensional leaf anatomy model. The anatomy and dark respiration of leaves of rice (Oryza sativa L.) were measured and used to compute O2 fluxes and partial pressure of O2 (pO2 ) in the DBL, gas film and leaf when submerged. The effects of floodwater pO2 , DBL thickness, cuticle permeability, presence of gas film and stomatal opening were explored. Under O2 -limiting conditions of the bulk water (pO2 < 10 kPa), the gas film significantly increases the O2 flux into submerged leaves regardless of whether stomata are fully or partly open. With a gas film, tissue pO2 substantially increases, even for the slightest stomatal opening, but not when stomata are completely closed. The effect of gas films increases with decreasing cuticle permeability. O2 flux and tissue pO2 decrease with increasing DBL thickness. The present modelling analysis provides a mechanistic understanding of how leaf gas films facilitate O2 entry into submerged plants.

Linking oxygen availability with membrane potential maintenance and K+ retention of barley roots: implications for waterlogging stress tolerance

Publisher: Wiley

Date: 18-08-2014

DOI: 10.1111/PCE.12422

Diversity in the genus Melilotus for tolerance to salinity and waterlogging

Publisher: Springer Science and Business Media LLC

Date: 16-01-2008

DOI: 10.1007/S11104-007-9523-Y

Aerenchyma and an Inducible Barrier to Radial Oxygen Loss Facilitate Root Aeration in Upland, Paddy and Deep-water Rice (Oryza sativa L.)

Publisher: Oxford University Press (OUP)

Date: 2003

DOI: 10.1093/AOB/MCF114

Abstract: The present study evaluated waterlogging tolerance, root porosity and radial O(2) loss (ROL) from the adventitious roots, of seven upland, three paddy, and two deep-water genotypes of rice (Oryza sativa L.). Upland types, with the exception of one genotype, were as tolerant of 30 d soil waterlogging as the paddy and deep-water types. In all but one of the 12 genotypes, the number of adventitious roots per stem increased for plants grown in waterlogged, compared with drained, soil. When grown in stagnant deoxygenated nutrient solution, genotypic variation was evident for root porosity and rates of ROL, but there was no overall difference between plants from the three cultural types. Adventitious root porosity increased from 20-26 % for plants grown in aerated solution to 29-41 % for plants grown in stagnant solution. Growth in stagnant solution also induced a 'tight' barrier to ROL in the basal regions of adventitious roots of five of the seven upland types, all three paddy types, and the two deep-water types. The enhanced porosity provided a low resistance pathway for O(2) movement to the root tip, and the barrier to ROL in basal zones would have further enhanced longitudinal O(2) diffusion towards the apex, by diminishing losses to the rhizosphere. The plasticity in root physiology, as described above, presumably contributes to the ability of rice to grow in erse environments that differ markedly in soil waterlogging, such as drained upland soils as well as waterlogged paddy fields.

Pattern of water use and seed yield under terminal drought in chickpea genotypes

Publisher: Frontiers Media SA

Date: 09-08-2017

DOI: 10.3389/FPLS.2017.01375

Tolerance of extreme salinity in two stem-succulent halophytes (Tecticornia species)

Publisher: CSIRO Publishing

Date: 2013

DOI: 10.1071/FP12304

Abstract: Communities of Tecticornia on the margins of ephemeral salt lakes in Australia often exhibit species zonation, such as at Hannan Lake (Western Australia) where Tecticornia indica subsp. bidens (Nees) K.A.Sheph. and Paul G.Wilson occupies the less saline dune habitat on lake margins and Tecticornia pergranulata (J.M.Black) K.A.Sheph. and Paul G.Wilson subsp. pergranulata occupies both the dunes and the more saline and moist lake playa. Here we tested the hypothesis that these two species differ in tolerance to extreme salinity. Plants were grown in drained sand cultures with treatments of 10–2000 mM NaCl for 85 days. Both species were highly salt tolerant, maintaining growth at treatments of up to 2000 mM NaCl, although the death of two replicates of T. indica at 2000 mM NaCl suggests this salinity is close to the species tolerance limit. Both Tecticornia species maintained a favourable gradient in tissue water potential via osmotic adjustment as external salinity increased, also with reduced tissue water content at very high external salinity. Regulated accumulation of Na+ and Cl–, maintenance of net K+ to Na+ selectivity, high tissue concentrations of glycinebetaine and presumed cellular solute compartmentation, would have contributed to salt tolerance. The growth rate of T. pergranulata was 11–29% higher than T. indica suggesting, in addition to these moderate differences in salinity tolerance, other factors are likely to contribute to species zonation at salt lakes. The higher water use efficiency of the C4 T. indica compared with the C3 T. pergranulata may provide an advantage in the drier dune habitat on salt lake margins. An additional experiment confirmed the hypothesis that survival of T. pergranulata seedlings is enhanced by the duration of reduced salinity after germination, as would occur following significant rainfall, as older seedlings maintained higher growth rates during subsequent increases in salinity.

Evaluation of a soil moisture sensor to reduce water and nutrient leaching in turfgrass (Cynodon dactylon cv. Wintergreen)

Publisher: CSIRO Publishing

Date: 2007

DOI: 10.1071/EA05189

Abstract: This study evaluated water application rates, leaching and quality of couch grass (Cynodon dactylon cv. Wintergreen) under a soil moisture sensor-controlled irrigation system, compared with plots under conventional irrigation scheduling as recommended for domestic lawns in Perth, Western Australia by the State’s water supplier. The cumulative volume of water applied during summer to the field plots of turfgrass with the sensor-controlled system was 25% less than that applied to plots with conventional irrigation scheduling. During 154 days over summer and autumn, about 4% of the applied water drained from lysimeters in sensor-controlled plots, and about 16% drained from lysimeters in plots with conventional irrigation scheduling. Even though losses of mineral nitrogen via leaching were extremely small (representing only 1.1% of the total nitrogen applied to conventionally irrigated plots), losses were significantly lower in the sensor-controlled plots. Total clippings produced were 18% lower in sensor-controlled plots. Turfgrass colour in sensor-controlled plots was reduced during summer, but colour remained acceptable under both treatments. The soil moisture sensor-controlled irrigation system enabled automatic implementation of irrigation events to match turfgrass water requirements.

The implementation of micro hydro projects in remote villages on the border of Indonesia and Malaysia: Lessons learnt

Publisher: Springer Science and Business Media LLC

Date: 11-06-2014

DOI: 10.1186/1471-2229-14-159

Growth responses of Melilotus siculus accessions to combined salinity and root-zone hypoxia are correlated with differences in tissue ion concentrations and not differences in root aeration

Publisher: Elsevier BV

Date: 2015

DOI: 10.1016/J.ENVEXPBOT.2014.08.006

Evidence for down‐regulation of ethanolic fermentation and K+ effluxes in the coleoptile of rice seedlings during prolonged anoxia

Publisher: Oxford University Press (OUP)

Date: 07-2001

DOI: 10.1093/JEXBOT/52.360.1507

Abstract: Ethanolic fermentation, the predominant catabolic pathway in anoxia-tolerant rice coleoptiles, was manipulated in excised and 'aged' tissues via glucose feeding. Coleoptiles with exogenous glucose survived 60 h of anoxia, as evidenced by vigorous rates of K+ and phosphate net uptake and growth of roots and shoots when re-aerated. In contrast, coleoptiles without exogenous glucose showed net losses of K+ and phosphates starting 12 h after anoxia was imposed and these did not recover fully when re-aerated after 60 h of anoxia. Ethanol production (micromol x g(-1) FW x h(-1)) declined from about 7.5 during the first 12 h of anoxia to 5 or 2.2 after 48-60 h, in coleoptiles with or without exogenous glucose, respectively. Carbohydrate concentrations changed only slightly in anoxic coleoptiles with exogenous glucose due to net glucose uptake at 2.6 micromol x g(-1) FW x h(-1). Ethanolic fermentation, and therefore ATP production, may have been down-regulated after an initial period of acclimation to anoxia in coleoptiles with exogenous glucose. Maintenance requirements for energy were assessed to be 3.4-7.6-fold lower in these anoxic coleoptiles than published estimates for non-growing aerated leaf tissues. A modest part of the required economy in energy consumption would have been derived from diminished ion transport anoxia reduced K+ and phosphate net uptake by 70-90% in these coleoptiles. K+ efflux was 10-fold lower in anoxic than in aerated coleoptiles with exogenous glucose. Using the unidirectional efflux equation, the membrane permeability to K+ was estimated to be 17-fold lower in anoxic than in aerated coleoptiles, presumably due to predominantly closed K+ channels.

Cost-effective large-scale occupancy-abundance monitoring of invasive brushtail possums (Trichosurus Vulpecula) on New Zealand's public conservation land

Publisher: Public Library of Science (PLoS)

Date: 06-2015

DOI: 10.1371/JOURNAL.PONE.0127693

Community recommendations on terminology and procedures used in flooding and low oxygen stress research

Publisher: Wiley

Date: 09-03-2017

DOI: 10.1111/NPH.14519

Plant salt tolerance: adaptations in halophytes

Publisher: Oxford University Press (OUP)

Date: 02-2015

DOI: 10.1093/AOB/MCU267

Abstract: Most of the water on Earth is seawater, each kilogram of which contains about 35 g of salts, and yet most plants cannot grow in this solution less than 0·2% of species can develop and reproduce with repeated exposure to seawater. These 'extremophiles' are called halophytes. Improved knowledge of halophytes is of importance to understanding our natural world and to enable the use of some of these fascinating plants in land re-vegetation, as forages for livestock, and to develop salt-tolerant crops. In this Preface to a Special Issue on halophytes and saline adaptations, the evolution of salt tolerance in halophytes, their life-history traits and progress in understanding the molecular, biochemical and physiological mechanisms contributing to salt tolerance are summarized. In particular, cellular processes that underpin the ability of halophytes to tolerate high tissue concentrations of Na+ and Cl−, including regulation of membrane transport, their ability to synthesize compatible solutes and to deal with reactive oxygen species, are highlighted. Interacting stress factors in addition to salinity, such as heavy metals and flooding, are also topics gaining increased attention in the search to understand the biology of halophytes. Halophytes will play increasingly important roles as models for understanding plant salt tolerance, as genetic resources contributing towards the goal of improvement of salt tolerance in some crops, for re-vegetation of saline lands, and as 'niche crops' in their own right for landscapes with saline soils.

Phenotypic variation for productivity and drought tolerance is widespread in germplasm collections of Australian Cullen species

Publisher: CSIRO Publishing

Date: 2012

DOI: 10.1071/CP11338

Abstract: Cullen australasicum is a legume species from Australia that holds promise for development as a drought-tolerant perennial pasture species, yet only a few accessions have been evaluated for agronomic traits. Several Cullen species aside from C. australasicum may also have potential for use as perennial pastures. We compared the field survival and aboveground biomass production of 100 germplasm accessions from 9 Cullen species, 2 lucerne (Medicago sativa) cultivars and 2 perennial Lotus species over 18 months in a low-rainfall region of the wheatbelt of Western Australia. Nutritive value of selected Cullen accessions was also compared with lucerne and L. australis. Several accessions of C. australasicum demonstrated good survival, productivity and nutritional value, and some accessions of C. discolor, C. lachnostachys, C. pallidum and C. pustulatum also showed promise in some or all of these traits. Significant phenotypic variation was seen among accessions of C. australasicum, C. pallidum, C. cinereum and C. tenax for some agronomic traits. We discuss the implications of this variation for further experiments or development of Cullen species. While survival and productivity of many Cullen accessions was similar to lucerne, only a few C. australasicum accessions were more productive than lucerne. We conclude that C. australasicum is currently the best prospect among Cullen species for cultivar development as a perennial pasture legume, and our analysis has highlighted accessions of particular interest. In addition, further work on C. discolor, C. lachnostachys, C. pallidum and C. pustulatum may also, in the longer term, provide useful pasture species.

Salt sensitivity in chickpea

Publisher: Wiley

Date: 02-03-2010

DOI: 10.1111/J.1365-3040.2009.02051.X

Abstract: The growth of chickpea (Cicer arietinum L.) is very sensitive to salinity, with the most susceptible genotypes dying in just 25 mm NaCl and resistant genotypes unlikely to survive 100 mm NaCl in hydroponics germination is more tolerant with some genotypes tolerating 320 mm NaCl. When growing in a saline medium, Cl(-), which is secreted from glandular hairs on leaves, stems and pods, is present in higher concentrations in shoots than Na(+). Salinity reduces the amount of water extractable from soil by a chickpea crop and induces osmotic adjustment, which is greater in nodules than in leaves or roots. Chickpea rhizobia show a higher 'free-living' salt resistance than chickpea plants, and salinity can cause large reductions in nodulation, nodule size and N(2)-fixation capacity. Recent screenings of erse germplasm suggest significant variation of seed yield under saline conditions. Both dominance and additive gene effects have been identified in the effects of salinity on chickpea and there appears to be sufficient genetic variation to enable improvement in yield under saline conditions via breeding. Selections are required across the entire life cycle with a range of rhizobial strains under salt-affected, preferably field, conditions.

Simultaneous analysis of amino and organic acids in extracts of plant leaves as tert-butyldimethylsilyl derivatives by capillary gas chromatography

Publisher: Elsevier BV

Date: 06-1998

DOI: 10.1006/ABIO.1998.2659

Abstract: The simultaneous determination of amino and organic acids in plant tissue extracts using capillary gas chromatography is described. Plant leaves were extracted in 5% (w/v) perchloric acid and neutralized extracts were purified using C18 cartridges. The amino and organic acids in purified extracts were then converted to tert-butyldimethylsilyl (TBDMS) derivatives prior to separation and detection by capillary gas chromatography (GC) with flame ionization detection. Conditions required for optimal derivatization were investigated. Amino and organic acids were readily converted to their TBDMS derivatives using N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide in dimethylformamide solvent 1:6 (v/v) with an average recovery of 90% and a reproducibility of about 5%. The characteristic [M-57] and [M-159] fragment ion of the TBDMS derivatives was confirmed using GC-MS. The proposed method was demonstrated by the determination of amino and organic acids in extracts of Acacia and Eucalyptus leaves, where detection limits were 1-20 ng.

Tissue-specific root ion profiling reveals essential roles of the CAX and ACA calcium transport systems in response to hypoxia in Arabidopsis

Publisher: Oxford University Press (OUP)

Date: 17-02-2016

DOI: 10.1093/JXB/ERW034

Regulation of root adaptive anatomical and morphological traits during low soil oxygen

Publisher: Wiley

Date: 11-02-2020

DOI: 10.1111/NPH.16375

Abstract: Flooding causes oxygen deprivation in soils. Plants adapt to low soil oxygen availability by changes in root morphology, anatomy, and architecture to maintain root system functioning. Essential traits include aerenchyma formation, a barrier to radial oxygen loss, and outgrowth of adventitious roots into the soil or the floodwater. We highlight recent findings of mechanisms of constitutive aerenchyma formation and of changes in root architecture. Moreover, we use modelling of internal aeration to demonstrate the beneficial effect of increasing cortex‐to‐stele ratio on sustaining root growth in waterlogged soils. We know the genes for some of the beneficial traits, and the next step is to manipulate these genes in breeding in order to enhance the flood tolerance of our crops.

Waterlogging tolerance and recovery of 10 Lotus species

Publisher: CSIRO Publishing

Date: 2008

DOI: 10.1071/EA07110

Abstract: Medicago sativa L. is the most widely sown perennial forage legume in farming systems of southern Australia. However, M. sativa lacks adaptation to winter waterlogged conditions. This constraint has highlighted the need for new perennial forage legumes adapted to winter waterlogged conditions and to locations where the summer is too dry for the survival of Trifolium repens L. and T. fragiferum L. To explore new perennial legume options suitable for these circumstances, 10 species of Lotus were evaluated for waterlogging tolerance including: two accessions of L. corniculatus L., four accessions of L. tenuis Waldst. & Kit., two accessions of L. pedunculatus Cav., two accessions of L. australis Andrew, three accessions of L. creticus L., three accessions of L. glaucus Sol., one accession of L. cruentus Court., one accession of L. argyrodes R.P. Murray, one accession of L. c ylocladus Webb & Berthel and one accession of L. latifolius Brand. These were compared with the M. sativa cultivar Sceptre. The ability to grow in waterlogged conditions, and to recover, was assessed in a pot experiment conducted over 19 weeks. The Lotus species most tolerant of waterlogging were L. corniculatus, L. tenuis and L. pedunculatus. Each of these species developed aerenchyma, adventitious roots, surface roots and split stems at the base to improve oxygen transport into the roots. Significant intra-species variation was also found within each of the three tolerant species, highlighting the opportunity for genetic improvement. By comparison, the remaining Lotus species were susceptible to waterlogging and showed poor recovery, whereas M. sativa Sceptre partially recovered after waterlogging.

Contrasting dynamics of radial O2-loss barrier induction and aerenchyma formation in rice roots of two lengths

Publisher: Oxford University Press (OUP)

Date: 22-11-2010

DOI: 10.1093/AOB/MCQ221

Differential tolerance to combined salinity and O2 deficiency in the halophytic grasses Puccinellia ciliata and Thinopyrum ponticum: The importance of K+ retention in roots

Publisher: Elsevier BV

Date: 03-2013

DOI: 10.1016/J.ENVEXPBOT.2012.09.006

Response of chickpea (Cicer arietinum L.) to terminal drought

Publisher: Oxford University Press (OUP)

Date: 19-04-2017

DOI: 10.1093/JXB/ERW153

Oxygen loss from seagrass roots coincides with colonisation of sulphide-oxidising cable bacteria and reduces sulphide stress

Publisher: Springer Science and Business Media LLC

Date: 23-10-2019

DOI: 10.1038/S41396-018-0308-5

Granular wetting agents ameliorate water repellency in turfgrass of contrasting soil organic matter content

Publisher: Springer Science and Business Media LLC

Date: 18-03-2011

DOI: 10.1007/S11104-011-0765-3

Turfgrass (Cynodon dactylon L.) sod production on sandy soils: I. Effects of irrigation and fertiliser regimes on growth and quality

Publisher: Springer Science and Business Media LLC

Date: 06-2006

DOI: 10.1007/S11104-006-0037-9

Development of Melilotus siculus – A New Salt and Waterlogging-tolerant Annual Fodder Legume Species for Mediterranean-type Climates

Publisher: Springer Netherlands

Date: 2010

DOI: 10.1007/978-90-481-8706-5_18

Physiological Adaptations to Wetland Habitats

Publisher: Springer Netherlands

Date: 2018

DOI: 10.1007/978-94-007-6172-8_79-2

Na⁺ and/or Cl⁻ Toxicities Determine Salt Sensitivity in Soybean (Glycine max (L.) Merr.), Mungbean (Vigna radiata (L.) R. Wilczek), Cowpea (Vigna unguiculata (L.) Walp.), and Common Bean (Phaseolus vulgaris L.)

Publisher: MDPI AG

Date: 14-02-2021

DOI: 10.3390/IJMS22041909

Abstract: Grain legumes are important crops, but they are salt sensitive. This research dissected the responses of four (sub)tropical grain legumes to ionic components (Na+ and/or Cl−) of salt stress. Soybean, mungbean, cowpea, and common bean were subjected to NaCl, Na+ salts (without Cl−), Cl− salts (without Na+), and a “high cation” negative control for 57 days. Growth, leaf gas exchange, and tissue ion concentrations were assessed at different growing stages. For soybean, NaCl and Na+ salts impaired seed dry mass (30% of control), more so than Cl− salts (60% of control). All treatments impaired mungbean growth, with NaCl and Cl− salt treatments affecting seed dry mass the most (2% of control). For cowpea, NaCl had the greatest adverse impact on seed dry mass (20% of control), while Na+ salts and Cl− salts had similar intermediate effects (~45% of control). For common bean, NaCl had the greatest adverse effect on seed dry mass (4% of control), while Na+ salts and Cl− salts impaired seed dry mass to a lesser extent (~45% of control). NaCl and Na+ salts (without Cl−) affected the photosynthesis (Pn) of soybean more than Cl− salts (without Na+) (50% of control), while the reverse was true for mungbean. Na+ salts (without Cl−), Cl− salts (without Na+), and NaCl had similar adverse effects on Pn of cowpea and common bean (~70% of control). In conclusion, salt sensitivity is predominantly determined by Na+ toxicity in soybean, Cl− toxicity in mungbean, and both Na+ and Cl− toxicity in cowpea and common bean.

De‐submergence‐induced ethylene production in Rumex palustris: regulation and ecophysiological significance

Publisher: Wiley

Date: 2003

DOI: 10.1046/J.1365-313X.2003.01632.X

Abstract: Rumex palustris responds to total submergence by increasing the elongation rate of young petioles. This favours survival by shortening the duration of submergence. Underwater elongation is stimulated by ethylene entrapped within the plant by surrounding water. However, abnormally fast extension rates were found to be maintained even when leaf tips emerged above the floodwater. This fast post-submergence growth was linked to a promotion of ethylene production that is presumed to compensate for losses brought about by ventilation. Three sources of ACC contributed to post-submergence ethylene production in R. palustris: (i) ACC that had accumulated in the roots during submergence and was transported in xylem sap to the shoot when stomata re-opened and transpiration resumed, (ii) ACC that had accumulated in the shoot during the preceding period of submergence and (iii) ACC produced de novo in the shoot following de-submergence. This new production of ethylene was associated with increased expression of an ACC synthase gene (RP-ACS1) and an ACC oxidase gene (RP-ACO1), increased ACC synthase activity and a doubling of ACC oxidase activity, measured in vitro. Out of seven species of Rumex examined, a de-submergence upsurge in ethylene production was seen only in shoots of those that had the ability to elongate fast when submerged.

Photosynthetic Performance and Fertility Are Repressed in GmAOX2b Antisense Soybean

Publisher: Oxford University Press (OUP)

Date: 22-01-2010

DOI: 10.1104/PP.109.149294

Abstract: The alternative oxidase (AOX) is a cyanide-resistant oxidase that provides an alternative outlet for electrons from the respiratory electron transport chain embedded in the inner membrane of plant mitochondria. Examination of soybean (Glycine max) plants carrying a GmAOX2b antisense gene showed AOX to have a central role in reproductive development and fecundity. In three independently transformed antisense lines, seed set was reduced by 16% to 43%, whereas ovule abortion increased by 1.2- to 1.7-fold when compared with nontransgenic transformation control plants. Reduced fecundity was associated with reductions in whole leaf cyanide-resistant, salicylhydroxamic acid-sensitive respiration and net photosynthesis, but there was no change in total respiration in the dark. The frequency of potential fertilization events was reduced by at least one-third in the antisense plants as a likely consequence of prefertilization defects. Pistils of the antisense plants contained a higher proportion of immature-sized, nonfertile embryo sacs compared with nontransgenic control plants. Increased rates of pollen abortion in vivo and reduced rates of pollen germination in vitro suggested that the antisense gene compromised pollen development and function. Reciprocal crosses between antisense and nontransgenic plants revealed that pollen produced by antisense plants was less active in fertilization. Taken together, the results presented here indicate that AOX expression has an important role in determining normal gametophyte development and function.

Salt tolerance in wild Hordeum species is associated with restricted entry of Na+ and Cl− into the shoots

Publisher: Oxford University Press (OUP)

Date: 12-07-2005

DOI: 10.1093/JXB/ERI229

Abstract: Eight wild Hordeum species: H. bogdanii, H. intercedens, H. jubatum, H. lechleri, H. marinum, H. murinum, H. patagonicum, and H. secalinum, and cultivated barley (H. vulgare) were grown in nutrient solution containing 0.2 (control), 150, 300, or 450 mol m(-3) NaCl. In saline conditions, the wild Hordeum species (except H. murinum) had better Na+ and Cl- 'exclusion', and maintained higher leaf K+, compared with H. vulgare. For ex le, at 150 mol m(-3) NaCl, the K+:Na+ in the youngest, fully expanded leaf blades of the wild Hordeum species was, on average, 5.2 compared with 0.8 in H. vulgare. In H. marinum grown in 300 mol m(-3) NaCl, K+ contributed 35% to leaf psi(pi), whereas Na+ and Cl- accounted for only 6% and 10%, respectively. By comparison, in H. vulgare grown at 300 mol m(-3) NaCl, K+ accounted for 19% and Na+ and Cl- made up 21% and 25% of leaf psi(pi), respectively. At 300 mol m(-3) NaCl, glycinebetaine and proline together contributed almost 15% to psi(pi) in the expanding leaf blades of H. marinum, compared with 8% in H. vulgare. Decreased tissue water content under saline conditions made a substantial contribution to declines in leaf psi(pi) in the wild Hordeum species, but not in H. vulgare. A number of the wild Hordeum species were markedly more salt tolerant than H. vulgare. H. marinum and H. intercedens, as ex les, had relative growth rates 30% higher than H. vulgare in 450 mol m(-3) NaCl. Hordeum vulgare also suffered up to 6-fold more dead leaf material (as a proportion of shoot dry mass) than the wild Hordeum species. Thus, several salt-tolerant wild Hordeum species were identified, and these showed an exceptional capacity to 'exclude' Na+ and Cl- from their shoots.

Expression of ?-expansin genes during root acclimations to O2 deficiency in Rumex palustris

Publisher: Springer Science and Business Media LLC

Date: 10-2004

DOI: 10.1007/S11103-004-3844-5

Abstract: Thirteen alpha-expansin genes were isolated from Rumex palustris , adding to the six already documented for this species. Five alpha-expansin genes were selected for expression studies in various organs/tissues of R. palustris , with a focus on roots exposed to aerated or O2)-deficient conditions, using real-time RT-PCR. Several cases of differential expression of alpha-expansin genes in the various root types of R. palustris were documented, and the identity of the dominant transcript differed between root types (i.e., tap root vs. lateral roots vs. adventitious roots). Several genes were expressed differentially in response to low O2. In situ hybridizations showed expansin mRNA expression in the oldest region of the tap root was localized to cells near the vascular cambium this being the first report of expansin expression associated with secondary growth in roots. In situ hybridization also showed abundant expression of expansin mRNA in the most apical 1 mm of adventitious roots. Such early expression of expansin mRNA in cells soon after being produced by the root apex presumably enables cell wall loosening in the elongation zone of roots. In addition, expression of some expansin mRNAs increased in 'mature zones' of roots these expansins might be involved in root hair formation or in formation of lateral root primordia. The present findings support the notion that large gene families of alpha-expansins enable flexibility in expression for various organs and tissues as a normal part of plant development, as well as in response to abiotic stress.

Drying half of the root-zone from mid fruit growth to maturity in ‘Hass’ avocado (Persea americana Mill.) trees for one season reduced fruit production in two years

Publisher: Elsevier BV

Date: 05-2009

DOI: 10.1016/J.SCIENTA.2008.12.010

Does N fertiliser regime influence N leaching and quality of different-aged turfgrass (Pennisetum clandestinum) stands?

Publisher: Springer Science and Business Media LLC

Date: 09-09-2009

DOI: 10.1007/S11104-008-9761-7

Aerenchyma formation and radial O₂ loss along adventitious roots of wheat with only the apical root portion exposed to O₂ deficiency

Publisher: Wiley

Date: 26-09-2003

DOI: 10.1046/J.1365-3040.2003.01089.X

pH regulation in anoxic rice coleoptiles at pH 3.5: biochemical pHstats and net H+ influx in the absence and presence of NO3−

Publisher: Oxford University Press (OUP)

Date: 15-12-2011

DOI: 10.1093/JXB/ERR395

The barrier to radial oxygen loss impedes the apoplastic entry of iron into the roots of Urochloa humidicola

Publisher: Oxford University Press (OUP)

Date: 05-02-2021

DOI: 10.1093/JXB/ERAB043

Abstract: Lack of O2 and high concentrations of iron (Fe) and manganese (Mn) commonly occur in waterlogged soils. The development of a barrier to impede radial O2 loss (ROL) is a key trait improving internal O2 transport and waterlogging tolerance in plants. We evaluated the ability of the barrier to ROL to impede the entry of excess Fe into the roots of the waterlogging-tolerant grass Urochloa humidicola. Plants were grown in aerated or stagnant deoxygenated nutrient solution with 5 µM or 900 µM Fe. Quantitative X-ray microanalysis was used to determine cell-specific Fe concentrations at two positions behind the root apex in relation to ROL and the formation of apoplastic barriers. At a mature zone of the root, Fe was ‘excluded’ at the exodermis where a suberized lamella was evident, a feature also associated with a strong barrier to ROL. In contrast, the potassium (K) concentration was similar in all root cells, indicating that K uptake was not affected by apoplastic barriers. The hypothesis that the formation of a tight barrier to ROL impedes the apoplastic entry of toxic concentrations of Fe into the mature zones of roots was supported by the significantly higher accumulation of Fe on the outer side of the exodermis.

Salinity and waterlogging tolerances in three stem-succulent halophytes (Tecticornia species) from the margins of ephemeral salt lakes

Publisher: Springer Science and Business Media LLC

Date: 30-07-2011

DOI: 10.1007/S11104-011-0924-6

Microsite and litter cover effects on seed banks vary with seed size and dispersal mechanisms: implications for revegetation of degraded saline land

Publisher: Springer Science and Business Media LLC

Date: 15-06-2012

DOI: 10.1007/S11258-012-0072-Y

Salt tolerance in a Hordeum marinum-Triticum aestivum amphiploid, and its parents

Publisher: Oxford University Press (OUP)

Date: 13-01-2007

DOI: 10.1093/JXB/ERL293

Abstract: Growth, grain production, and physiological traits were evaluated for Hordeum marinum, Triticum aestivum (cv. Chinese Spring), and a H. marinum-T. aestivum hiploid, when exposed to NaCl treatments in a nutrient solution. H. marinum was more salt tolerant than T. aestivum and the hiploid was intermediate, both for vegetative growth and relative grain production. H. marinum was best able to 'exclude' Na(+) and Cl(-), particularly at high external NaCl. At 300 mM NaCl, concentrations of Na(+) (153 micromol g(-1) dry mass) and Cl(-) (75 micromol g(-1) dry mass) in the youngest fully-expanded leaf blade of H. marinum were, respectively, only 7% and 4% of those in T. aestivum and in the hiploid the Na(+) and Cl(-) concentrations were 39% and 36% of those in T. aestivum. Glycinebetaine and proline concentrations in the youngest fully-expanded leaf blade of plants exposed to 200 mM NaCl were highest in H. marinum (128 and 60 micromol g(-1) dry mass, respectively), lowest in T. aestivum (85 and 37 micromol g(-1) dry mass), and intermediate in the hiploid (108 and 54 micromol g(-1) dry mass). Thus, salt tolerance of H. marinum was expressed in the H. marinum-T. aestivum hiploid.

Corrigendum: Waterlogging of Winter Crops at Early and Late Stages: Impacts on Leaf Physiology, Growth and Yield

Publisher: Frontiers Media SA

Date: 04-02-2020

DOI: 10.3389/FPLS.2019.01806

Similarity and diversity in adventitious root anatomy as related to root aeration among a range of wetland and dryland grass species

Publisher: Wiley

Date: 03-2002

DOI: 10.1046/J.0016-8025.2001.00817.X

Regulation of intracellular pH during anoxia in rice coleoptiles in acidic and near neutral conditions

Publisher: Oxford University Press (OUP)

Date: 10-04-2009

DOI: 10.1093/JXB/ERP090

Anatomical and biochemical characterisation of a barrier to radial O2 loss in adventitious roots of two contrasting Hordeum marinum accessions

Publisher: CSIRO Publishing

Date: 2017

DOI: 10.1071/FP16327

Abstract: A barrier to radial O2 loss (ROL) in roots is an adaptive trait of waterlogging-tolerant plants. Hordeum marinum Huds. is a waterlogging-tolerant species that, in contrast to its waterlogging-sensitive cultivated relatives, forms a tight barrier to ROL in basal root zones. To evaluate the nature of the barrier to ROL in roots, we combined measurements of ROL with histochemical and biochemical studies of two contrasting H. marinum accessions. H21 formed greater aerenchyma (up to 38% of cross-sectional area) and a tight barrier to ROL when grown under deoxygenated stagnant conditions, whereas the barrier was only partially formed in roots of H90 and aerenchyma was up to 26%. A tight barrier to ROL in roots of H21 corresponded with strong suberisation of the exodermis. In agreement with anatomical studies, almost all aliphatic suberin quantities were greater in roots of H21 grown under stagnant conditions compared with roots from aerated controls, and also to those in H90. By contrast to suberin, no differences in root lignification were observed between the two accessions raised in either aerated or stagnant conditions. These findings show that in adventitious roots of H. marinum, suberisation rather than lignification restricts ROL from the basal root zones.

Two key genomic regions harbour QTLs for salinity tolerance in ICCV 2 × JG 11 derived chickpea (Cicer arietinum L.) recombinant inbred lines

Publisher: Springer Science and Business Media LLC

Date: 22-05-2015

DOI: 10.1186/S12870-015-0491-8

Salt Stress Delayed Flowering and Reduced Reproductive Success of Chickpea (Cicer arietinum L.), A Response Associated with Na+ Accumulation in Leaves

Publisher: Wiley

Date: 11-03-2016

DOI: 10.1111/JAC.12128

Salinity tolerance and ion accumulation in chickpea (Cicer arietinum L.) subjected to salt stress

Publisher: Springer Science and Business Media LLC

Date: 09-08-2013

DOI: 10.1007/S11104-012-1387-0

Leaf gas films contribute to rice (Oryza sativa) submergence tolerance during saline floods

Publisher: Wiley

Date: 23-02-2018

DOI: 10.1111/PCE.12873

Abstract: Floods and salinization of agricultural land adversely impact global rice production. We investigated whether gas films on leaves of submerged rice delay salt entry during saline submergence. Two-week-old plants with leaf gas films (+GF) or with gas films experimentally removed (-GF) were submerged in artificial floodwater with 0 or 50 mm NaCl for up to 16 d. Gas films were present >9 d on GF plants after which gas films were diminished. Tissue ion analysis (Na

Alternative oxidase, a determinant of plant gametophyte fitness and fecundity

Publisher: Informa UK Limited

Date: 05-2010

DOI: 10.4161/PSB.11502

EST-derived SSR markers from defined regions of the wheat genome to identifyLophopyrum elongatumspecific loci

Publisher: Canadian Science Publishing

Date: 10-2005

DOI: 10.1139/G05-040

Abstract: Lophopyrum elongatum, a close relative of wheat, provides a source of novel genes for wheat improvement. Molecular markers were developed to monitor the introgression of L. elongatum chromosome segments into hexaploid wheat. Existing simple sequence repeats (SSRs) derived from genomic libraries were initially screened for detecting L. elongatum loci in wheat, but only 6 of the 163 markers tested were successful. To increase detection of L. elongatum specific loci, 165 SSRs were identified from wheat expressed sequence tags (ESTs), where their chromosomal positions in wheat were known from deletion bin mapping. Detailed sequence analysis identified 41 SSRs within this group as potentially superior in their ability to detect L. elongatum loci. BLASTN alignments were used to position primers within regions of the ESTs that have sequence conservation with at least 1 similar EST from another cereal species. The targeting of primers in this manner enabled 14 L. elongatum markers from 41 wheat ESTs to be identified, whereas only 2 from 124 primers designed in random positions flanking SSRs detected L. elongatum loci. Addition and ditelosomic lines were used to assign all 22 markers to specific chromosome locations in L. elongatum. Nine of these SSR markers were assigned to homoeologous chromosome locations based on their similar position in hexaploid wheat. The remaining markers mapped to other L. elongatum chromosomes indicating a degree of chromosome rearrangements, paralogous sequences and (or) sequence variation between the 2 species. The EST-SSR markers were also used to screen other wheatgrass species indicating further chromosome rearrangements and (or) sequence variation between wheatgrass genomes. This study details methodologies for the generation of SSRs for detecting L. elongatum loci.Key words: Lophopyrum elongatum, expressed sequence tags (EST), simple sequence repeat (SSR), EST-SSR, synteny, alien introgression.

Salt sensitivity in chickpea: Growth, photosynthesis, seed yield components and tissue ion regulation in contrasting genotypes

Publisher: Elsevier BV

Date: 06-2015

DOI: 10.1016/J.JPLPH.2015.05.002

Abstract: Chickpea is a relatively salt sensitive species but shows genotypic variation for salt tolerance, measured as grain yield per plant in mild-to-moderately saline soil. This experiment was designed to evaluate some physiological responses to salinity in three contrasting genotypes. One tolerant (Genesis836), one moderately tolerant (JG11) and one sensitive (Rupali) genotype were grown for 108d in non-saline nutrient solution (controls) and two levels of salinity treatment (30 and 60mM NaCl). No plants survived to maturity in the 60mM NaCl treatment however, Genesis836 survived longer (87d) than JG11 (67d) while Rupali died after 27d only Genesis836 flowered, but no pods were filled. At 30mM NaCl, Genesis836 produced a few filled pods, whereas JG11 and Rupali did not. Genotypic differences in plant dry mass at the vegetative stage were evident only at 60mM NaCl, while at maturity differences were evident at 30mM NaCl. Photosynthesis was maintained to different degrees by the three genotypes (e.g. at 30mM NaCl, 35-81% of controls highest in Genesis836) photosynthesis was restricted predominately due to non-stomatal limitations as the intercellular CO2 concentration was only modestly affected (94-99% of controls). Photosystem II damage was evident in the less tolerant genotypes (e.g. at 30mM NaCl, actual quantum efficiency of photosystem II values were 63-96% of controls). Across treatments, shoot dry mass was negatively correlated with both Na(+) and Cl(-) shoot concentrations. However, the sensitive genotype (Rupali) had equal or lower concentrations of these ions in green leaves, stems or roots compared to tolerant genotypes (JG11 and Genesis836) ion 'exclusion' does not explain variation for salt tolerance among these three chickpea genotypes. The large difference between Rupali (sensitive) and Genesis836 (tolerant) in the salt-induced reduction in net photosynthesis via non-stomatal limitations and the assessed damage to photosystem II, but with similar leaf ion concentrations, provides evidence that variation in 'tissue tolerance' of Na(+) and/or Cl(-) in leaves contributes to the differential salt tolerance of these chickpea genotypes.

Comparative transcriptome analysis reveals molecular regulation of salt tolerance in two contrasting chickpea genotypes

Publisher: Frontiers Media SA

Date: 30-05-2023

DOI: 10.3389/FPLS.2023.1191457

Abstract: Salinity is a major abiotic stress that causes substantial agricultural losses worldwide. Chickpea ( Cicer arietinum L.) is an important legume crop but is salt-sensitive. Previous physiological and genetic studies revealed the contrasting response of two desi chickpea varieties, salt-sensitive Rupali and salt-tolerant Genesis836, to salt stress. To understand the complex molecular regulation of salt tolerance mechanisms in these two chickpea genotypes, we examined the leaf transcriptome repertoire of Rupali and Genesis836 in control and salt-stressed conditions. Using linear models, we identified categories of differentially expressed genes (DEGs) describing the genotypic differences: salt-responsive DEGs in Rupali (1,604) and Genesis836 (1,751) with 907 and 1,054 DEGs unique to Rupali and Genesis836, respectively, salt responsive DEGs (3,376), genotype-dependent DEGs (4,170), and genotype-dependent salt-responsive DEGs (122). Functional DEG annotation revealed that the salt treatment affected genes involved in ion transport, osmotic adjustment, photosynthesis, energy generation, stress and hormone signalling, and regulatory pathways. Our results showed that while Genesis836 and Rupali have similar primary salt response mechanisms (common salt-responsive DEGs), their contrasting salt response is attributed to the differential expression of genes primarily involved in ion transport and photosynthesis. Interestingly, variant calling between the two genotypes identified SNPs/InDels in 768 Genesis836 and 701 Rupali salt-responsive DEGs with 1,741 variants identified in Genesis836 and 1,449 variants identified in Rupali. In addition, the presence of premature stop codons was detected in 35 genes in Rupali. This study provides valuable insights into the molecular regulation underpinning the physiological basis of salt tolerance in two chickpea genotypes and offers potential candidate genes for the improvement of salt tolerance in chickpeas.

Pattern of solutes accumulated during leaf osmotic adjustment as related to duration of water deficit for wheat at the reproductive stage

Publisher: Elsevier BV

Date: 10-2011

DOI: 10.1016/J.PLAPHY.2011.05.011

Abstract: This study examined expression of osmotic adjustment (OA) and accumulation of solutes in wheat (Triticum aestivum L.) leaves in response to water deficit (WD) imposed at the reproductive stage. Two contrasting cultivars, Hartog and Sunco (putatively high and low in OA capacity, respectively), were grown in deep (viz. 80 cm) pots in a controlled environment. In a sandy substrate, leaf OA was 5-times greater in Hartog compared with Sunco. At 21 d of WD treatment, K(+) only accounted for 12% of OA in Hartog and 48% in Sunco with less OA (i.e. tissue K(+) led to different proportions owing to different magnitudes of OA). Glycinebetaine and proline also increased under WD, but these were not significant osmotica on a whole tissue basis. Hartog accumulated dry matter faster than Sunco under WD, and this was consistent with greater water extraction by Hartog than by Sunco. In a second experiment on Hartog, with loam added to the sand to increase water-holding capacity and thus enable a longer draw-down period, leaf OA increased to 0.37 MPa at 37 d of withholding water. K(+) increased up to 16 d of drying and then decreased towards 37 d. Glycinebetaine, proline, glucose and fructose all increased during the draw-down period, although with different dynamics e.g. glycinebetaine increased linearly whereas glucose showed an exponential increase. By contrast, sucrose declined. K(+) was the major contributor to OA (viz. 54%) up to 30 d of drying, whereas glycinebetaine, proline and glucose were major contributors later (at d 37 these organic solutes each accounted for 19, 21 and 21% of OA). Thus, the various solutes that contributed to leaf OA in wheat cv. Hartog accumulated at different times as WD developed.

Neglecting legumes has compromised human health and sustainable food production

Publisher: Springer Science and Business Media LLC

Date: 02-08-2016

DOI: 10.1038/NPLANTS.2016.112

Abstract: The United Nations declared 2016 as the International Year of Pulses (grain legumes) under the banner 'nutritious seeds for a sustainable future'. A second green revolution is required to ensure food and nutritional security in the face of global climate change. Grain legumes provide an unparalleled solution to this problem because of their inherent capacity for symbiotic atmospheric nitrogen fixation, which provides economically sustainable advantages for farming. In addition, a legume-rich diet has health benefits for humans and livestock alike. However, grain legumes form only a minor part of most current human diets, and legume crops are greatly under-used. Food security and soil fertility could be significantly improved by greater grain legume usage and increased improvement of a range of grain legumes. The current lack of coordinated focus on grain legumes has compromised human health, nutritional security and sustainable food production.

Flooding tolerance in halophytes

Publisher: Wiley

Date: 06-08-2008

DOI: 10.1111/J.1469-8137.2008.02483.X

Abstract: Flooding is a common environmental variable with salinity. Submerged organs can suffer from O 2 deprivation and the resulting energy deficits can compromise ion transport processes essential for salinity tolerance. Tolerance of soil waterlogging in halophytes, as in glycophytes, is often associated with the production of adventitious roots containing aerenchyma, and the resultant internal O 2 supply. For some species, shallow rooting in aerobic upper soil layers appears to be the key to survival on frequently flooded soils, although little is known of the anoxia tolerance in halophytes. Halophytic species that inhabit waterlogged substrates are able to regulate their shoot ion concentrations in spite of the hypoxic (or anoxic) medium in which they are rooted, this being in stark contrast with most other plants which suffer when salinity and waterlogging occur in combination. Very few studies have addressed the consequences of submergence of the shoots by saline water these have, however, demonstrated tolerance of temporary submergence in some halophytes.

Development and use of a variable-speed lateral boom irrigation system to define water requirements of 11 turfgrass genotypes under field conditions

Publisher: CSIRO Publishing

Date: 2007

DOI: 10.1071/EA05157

Abstract: Improved irrigation scheduling is one strategy by which water management can be improved in turfgrass systems. The development and testing of a variable-speed lateral boom irrigation system for use in field-based irrigation trials is reported. Christiansen’s coefficient of uniformity was greater than 92% and the efficiency of irrigator discharge was greater than 90% for application depths (mm/unit land area) of 0.5–13 mm. The minimum irrigation requirements were determined for 11 turfgrass genotypes from a summer irrigation dose–response field trial that applied daily treatments of 100 (control), 80, 60, 40 and 20% of the previous day’s net evaporation measured using a US Class A pan. Responses of several shoot parameters, including clipping production, green leaf area index, leaf chlorophyll and leaf water status were evaluated to define minimum irrigation requirements for the turfgrasses. Minimum irrigation requirements (as defined by declines of 10% in several shoot responses) for C3 and C4 turfgrasses were 64–94% and 32–78% of US Class A pan, respectively. Variability in irrigation requirements within C3 or C4 types was due mainly to variations in estimates based on the different shoot parameters. The results demonstrate the opportunity for water conservation by using C4 rather than C3 turfgrasses in locations with hot dry summers (and mild winters) typical of a Mediterranean-type climate.

Salt tolerance in Eucalyptus spp.: Identity and response of putative osmolytes

Publisher: Wiley

Date: 16-03-2005

DOI: 10.1111/J.1365-3040.2005.01328.X

Water uptake by roots of Hordeum marinum: formation of a barrier to radial O2 loss does not affect root hydraulic conductivity

Publisher: Oxford University Press (OUP)

Date: 12-01-2006

DOI: 10.1093/JXB/ERJ055

Abstract: The adventitious roots of Hordeum marinum grown in stagnant deoxygenated solution contain a barrier to radial O2 loss (ROL) in basal zones, whereas roots of plants grown in aerated solution do not. The present experiments assessed whether induction of the barrier to ROL influences root hydraulic conductivity (Lpr). Wheat (Triticum aestivum) was also studied since, like H. marinum, this species forms aerenchyma in stagnant conditions, but does not form a barrier to ROL. Plants were grown in either aerated or stagnant, deoxygenated nutrient solution for 21-28 d. Root-sleeving O2 electrodes were used to assess patterns of ROL along adventitious roots, and a root-pressure probe and a pressure chamber to measure Lpr for in idual adventitious roots and whole root systems, respectively. Lpr, measured under a hydrostatic pressure gradient, was 1.8-fold higher for in idual roots, and 5.6-fold higher for whole roots systems, in T. aestivum than H. marinum. However, there was no difference in Lpr between the two species when measured under an osmotic driving force, when water moved from cell to cell rather than apoplastically. Root-zone O2 treatments during growth had no effect on Lpr for either species (measured in aerobic solution). It is concluded that induction of the barrier to ROL in H. marinum did not significantly affect the hydraulic conductivity of either in idual adventitious roots or of the whole root system.

Lotus tenuis tolerates combined salinity and waterlogging: maintaining O2 transport to roots and expression of an NHX1-like gene contribute to regulation of Na+ transport

Publisher: Wiley

Date: 23-04-2010

DOI: 10.1111/J.1399-3054.2010.01373.X

Abstract: Salinity and waterlogging interact to reduce growth for most crop and pasture species. The combination of these stresses often cause a large increase in the rate of Na(+) and Cl(-) transport to shoots however, the mechanisms responsible for this are largely unknown. To identify mechanisms contributing to the adverse interaction between salinity and waterlogging, we compared two Lotus species with contrasting tolerances when grown under saline (200 mM NaCl) and O(2)-deficient (stagnant) treatments. Measurements of radial O(2) loss (ROL) under stagnant conditions indicated that more O(2) reaches root tips of Lotus tenuis, compared with Lotus corniculatus. Better internal aeration would contribute to maintaining Na(+) and Cl(-) transport processes in roots of L. tenuis exposed to stagnant-plus-NaCl treatments. L. tenuis root Na(+) concentrations after stagnant-plus-NaCl treatment (200 mM) were 17% higher than L. corniculatus, with 55% of the total plant Na(+) being accumulated in roots, compared with only 39% for L. corniculatus. L. tenuis accumulated more Na(+) in roots, presumably in vacuoles, thereby reducing transport to the shoot (25% lower than L. corniculatus). A candidate gene for vacuole Na(+) accumulation, an NHX1-like gene, was cloned from L. tenuis and identity established via sequencing and yeast complementation. Transcript levels of NHX1 in L. tenuis roots under stagnant-plus-NaCl treatment were the same as for aerated NaCl, whereas L. corniculatus roots had reduced transcript levels. Enhanced O(2) transport to roots enables regulation of Na(+) transport processes in L. tenuis roots, contributing to tolerance to combined salinity and waterlogging stresses.

Salt sensitivity in chickpea (Cicer arietinumL.): Ions in reproductive tissues and yield components in contrasting genotypes

Publisher: Wiley

Date: 04-03-2015

DOI: 10.1111/PCE.12506

Abstract: The reproductive phase in chickpea (Cicer arietinum L.) is affected by salinity, but little is known about the underlying cause. We investigated whether high concentrations of Na(+) and Cl(-) in the reproductive structures influence reproductive processes. Chickpea genotypes contrasting in tolerance were subjected to 0, 35 or 50 mm NaCl applied to soil in pots. Flower production and abortion, pod number, percentage of empty pods, seed number and size were evaluated. The concentrations of Na(+) , K(+) and Cl(-) were measured in various plant tissues and, using X-ray microanalysis, in specific cells of developing reproductive structures. Genotypic variation in reproductive success measured as seed yield in saline conditions was associated with better maintenance of flower production and higher numbers of filled pods (and thus seed number), whereas seed size decreased in all genotypes. Despite the variation in reproductive success, the accumulation of Na(+) and Cl(-) in the early reproductive tissues of developing pods did not differ between a tolerant (Genesis836) and a sensitive (Rupali) genotype. Similarly, salinity tolerance was not associated with the accumulation of salt ions in leaves at the time of reproduction or in seeds at maturity.

Simultaneous determination by capillary gas chromatography of organic acids, sugars, and sugar alcohols in plant tissue extracts as their trimethylsilyl derivatives

Publisher: Elsevier BV

Date: 1999

DOI: 10.1006/ABIO.1998.2906

Abstract: A capillary gas chromatographic (GC) method for the simultaneous determination of organic acids, sugars, and sugar alcohols extracted from plant tissues is described. Plant leaves were extracted in 5% (w/v) perchloric acid and neutralized extracts were purified using C18 cartridges. Organic acids, sugars, and sugar alcohols in purified extracts were converted to their trimethylsilyl (TMS)/TMS-oxime derivatives prior to separation and detection by capillary GC with flame ionization detection (FID). Derivatization procedures were investigated in detail and the compounds of interest were readily converted to their TMS/TMS-oxime derivatives using hexamethyldisiazane reagent in acetonitrile solvent (1:6 v/v) at 100 degreesC for 60 min. The derivatives were sufficiently volatile and stable. The FID response to derivatized compounds was generally linear in the concentration range 30-300 microg ml-1, with detection limits in the order of 3-76 ng. The proposed method was demonstrated for the determination of organic acids, sugars, and sugar alcohols in leaf extracts of two native Australian plants.

Role of ethylene in acclimations to promote oxygen transport in roots of plants in waterlogged soils

Publisher: Elsevier BV

Date: 07-2008

DOI: 10.1016/J.PLANTSCI.2008.03.002

Plant responses to heterogeneous salinity: growth of the halophyte Atriplex nummularia is determined by the root-weighted mean salinity of the root zone

Publisher: Oxford University Press (OUP)

Date: 11-2012

DOI: 10.1093/JXB/ERS302

Superior salt tolerance in wild soybean (G. soja) is associated with better ion ‘exclusion’ ability from leaves and mesophyll cells than cultivated soybean genotypes (G. max)

Publisher: Elsevier BV

Date: 07-2023

DOI: 10.1016/J.ENVEXPBOT.2023.105348

Evaluation of root porosity and radial oxygen loss of disomic addition lines of Hordeum marinum in wheat

Publisher: CSIRO Publishing

Date: 2017

DOI: 10.1071/FP16272

Abstract: Hordeum marinum Huds. is a waterlogging-tolerant wild relative of wheat (Triticum aestivum L.). Greater root porosity (gas volume per root volume) and formation of a barrier to reduce root radial O2 loss (ROL) contribute to the waterlogging tolerance of H. marinum and these traits are evident in some H. marinum–wheat hiploids. We evaluated root porosity, ROL patterns and tolerance to hypoxic stagnant conditions for 10 various H. marinum (two accessions) disomic chromosome addition (DA) lines in wheat (two varieties), produced from two H. marinum–wheat hiploids and their recurrent wheat parents. None of the DA lines had a barrier to ROL or higher root porosity than the wheat parents. Lack of a root ROL barrier in the six DA lines for H. marinum accession H21 in Chinese Spring (CS) wheat indicates that the gene(s) for this trait do not reside on one of these six chromosomes unfortunately, chromosome 3 of H. marinum has not been isolated in CS. Unlike the H21–CS hiploid, which formed a partial ROL barrier in roots, the H90–Westonia hiploid and the four derived DA lines available did not. The unaltered root aeration traits in the available DA lines challenge the strategy of using H. marinum as a donor of these traits to wheat.

Root Physiology

Publisher: Springer Netherlands

Date: 2005

DOI: 10.1007/1-4020-4099-7

Root physiology - from gene to function

Publisher: Springer Science and Business Media LLC

Date: 07-2005

DOI: 10.1007/S11104-005-0964-X

Physiological Mechanisms of Flooding Tolerance in Rice: Transient Complete Submergence and Prolonged Standing Water

Publisher: Springer Berlin Heidelberg

Date: 07-2013

DOI: 10.1007/978-3-642-38797-5_9

Adaptation of Rice to Flooded Soils

Publisher: Springer Berlin Heidelberg

Date: 07-2013

DOI: 10.1007/978-3-642-38797-5_8

Gas film retention and underwater photosynthesis during field submergence of four contrasting rice genotypes

Publisher: Oxford University Press (OUP)

Date: 23-04-2014

DOI: 10.1093/JXB/ERU166

Underwater photosynthesis and respiration in leaves of submerged wetland plants: gas films improve CO ₂ and O ₂ exchange

Publisher: Wiley

Date: 10-12-2008

DOI: 10.1111/J.1469-8137.2007.02318.X

Abstract: DOI: 10.1111/j.1469-8137.2007.02372.x

Changes in growth, porosity, and radial oxygen loss from adventitious roots of selected mono‐ and dicotyledonous wetland species with contrasting types of aerenchyma

Publisher: Wiley

Date: 11-2000

DOI: 10.1046/J.1365-3040.2000.00628.X

Aerenchymatous phellem in hypocotyl and roots enables O₂ transport in Melilotus siculus

Publisher: Wiley

Date: 08-02-2011

DOI: 10.1111/J.1469-8137.2011.03655.X

Abstract: • Aerenchymatous phellem (secondary aerenchyma) has rarely been studied in roots. Its formation and role in internal aeration were evaluated for Melilotus siculus, an annual legume of wet saline land. • Plants were grown for 21 d in aerated or stagnant (deoxygenated) agar solutions. Root porosity and maximum diameters were measured after 0, 7, 14 and 21 d of treatment. Phellem anatomy was studied and oxygen (O(2)) transport properties examined using methylene blue dye and root-sleeving O(2) electrodes. • Interconnecting aerenchymatous phellem developed in hypocotyl, tap root and older laterals (but not in aerial shoots), with radial intercellular connections to steles. Porosity of main roots containing phellem was c. 25% cross-sectional areas of this phellem were threefold greater for stagnant than for aerated treatments. Root radial O(2) loss was significantly reduced by complete hypocotyl submergence values approached zero after disruption of hypocotyl phellem below the waterline or, after shoot excision, by covering hypocotyl phellem in nontoxic cream. • Aerenchymatous phellem enables hypocotyl-to-root O(2) transport in M. siculus. Phellem increases radially under stagnant conditions, and will contribute to waterlogging tolerance by enhancing root aeration. It seems likely that with hypocotyl submerged, O(2) will diffuse via surface gas-films and internally from the shoot system.

Internal aeration of paddy field rice ( Oryza sativa ) during complete submergence - importance of light and floodwater O ₂

Publisher: Wiley

Date: 06-12-2013

DOI: 10.1111/NPH.12048

Abstract: Flash floods can submerge paddy field rice ( O ryza sativa ), with adverse effects on internal aeration, sugar status and survival. Here, we investigated the in situ aeration of roots of rice during complete submergence, and elucidated how underwater photosynthesis and floodwater p O 2 influence root aeration in anoxic soil. In the field, root p O 2 was measured using microelectrodes during 2 d of complete submergence. Leaf gas films that formed on the superhydrophobic leaves were left intact, or experimentally removed, to elucidate their effect on internal aeration. In darkness, root p O 2 declined to very low concentrations (0.24 kPa) and was strongly correlated with floodwater p O 2 . In light, root p O 2 was high (14 kPa) and primarily a function of the incident light determining the rates of underwater net photosynthesis. Plants with intact leaf gas films maintained higher underwater net photosynthesis relative to plants without gas films when the submerged shoots were in light. During complete submergence, internal aeration of rice in the field relies on underwater photosynthesis during the day and entry of O 2 from the floodwater during the night. Leaf gas films enhance photosynthesis during submergence leading to improved O 2 production and sugar status, and therefore contribute to the submergence tolerance of rice.

Energy costs of salinity tolerance in crop plants

Publisher: Wiley

Date: 29-11-2019

DOI: 10.1111/NPH.15555

Salinity drives host reaction in Phaseolus vulgaris (common bean) to Macrophomina phaseolina

Publisher: CSIRO Publishing

Date: 2011

DOI: 10.1071/FP11137

Abstract: Productivity of Phaseolus vulgaris L. (common bean) is often limited by diseases such as seedling blight and root and stem rot caused by the fungus Macrophomina phaseolina and by abiotic stresses such as salinity. This paper reports controlled environment studies examining the interaction of biotic (M. phaseolina) and abiotic (NaCl) stresses. Studies were conducted at 32°C. On potato dextrose agar, the growth of two isolates of M. phaseolina (M1, M2) was differentially stimulated by 40 mM NaCl with 1 mM CaSO4. M. phaseolina was applied as either soil-borne inoculum or directly injected into P. vulgaris hypocotyls. For direct hypocotyl inoculation experiments, there was no difference in disease severity resulting from the two isolates. However, when soil inoculation was undertaken, isolate M2 caused more disease than M1. Addition of 40 mM NaCl to the soil increased disease development and severity (evident 4 days after inoculation), particularly as demonstrated in the hypocotyl inoculation tests, suggesting that salinity stress predisposes plants to infection by this pathogen. Plants infested by M. phaseolina showed increased tissue concentrations of Na+ and Cl– but decreased K+ concentration. Hypocotyls generally contained higher Na+ concentrations than shoots. Inoculated plants had higher Na+ and lower K+ concentrations than uninoculated plants. Our studies indicate that M. phaseolina will be a more severe disease threat where P. vulgaris is cultivated in areas affected by soil salinity.

Salinity tolerances of three succulent halophytes (Tecticornia spp.) differentially distributed along a salinity gradient

Publisher: CSIRO Publishing

Date: 2016

DOI: 10.1071/FP16025

Abstract: We evaluated tolerances to salinity (10–2000 mM NaCl) in three halophytic succulent Tecticornia species that are differentially distributed along a salinity gradient at an ephemeral salt lake. The three species showed similar relative shoot and root growth rates at 10–1200 mM NaCl at 2000 mM NaCl, T. indica subsp. bidens (Nees) K.A.Sheph and P.G.Wilson died, but T. medusa (K.A.Sheph and S.J.van Leeuwen) and T. auriculata (P.G.Wilson) K.A.Sheph and P.G.Wilson survived but showed highly diminished growth rates and were at incipient water stress. The mechanisms of salinity tolerance did not differ among the three species and involved the osmotic adjustment of succulent shoot tissues by the accumulation of Na+, Cl– and the compatible solute glycinebetaine, and the maintenance of high net K+ to Na+ selectivity to the shoot. Growth at extreme salinity was presumably limited by the capacity for vacuolar Na+ and Cl– uptake to provide sufficiently low tissue osmotic potentials for turgor-driven growth. Tissue sugar concentrations were not reduced at high salinity, suggesting that declines in growth would not have been caused by inadequate photosynthesis and substrate limitation compared with plants at low salinity. Equable salt tolerance among the three species up to 1200 mM NaCl means that other factors are likely to contribute to species composition at sites with salinities below this level. The lower NaCl tolerance threshold for survival in T. indica suggests that this species would be competitively inferior to T. medusa and T. auriculata in extremely saline soils.

Photosynthetic response to globally increasing CO₂ of co‐occurring temperate seagrass species

Publisher: Wiley

Date: 22-03-2016

DOI: 10.1111/PCE.12658

Abstract: Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 (-) . Net photosynthesis of all species except Zostera polychlamys were limited at pre-industrial compared to saturating CO2 levels at light saturation, suggesting that enhanced CO2 availability will enhance seagrass performance. Seven out of the nine species were efficient HCO3 (-) users through acidification of diffusive boundary layers, production of extracellular carbonic anhydrase, or uptake and internal conversion of HCO3 (-) . Species responded differently to near saturating CO2 implying that increasing atmospheric CO2 may change competition among seagrass species if co-occurring in mixed beds. Increasing CO2 availability also enhanced internal aeration in the one species assessed. We expect that future increases in atmospheric CO2 will have the strongest impact on seagrass recruits and sparsely vegetated beds, because densely vegetated seagrass beds are most often limited by light and not by inorganic carbon.

Improving crop salt tolerance using transgenic approaches

Publisher: Wiley

Date: 15-09-2020

DOI: 10.1111/PCE.13865

Submergence tolerance in Hordeum marinum: dissolved CO2 determines underwater photosynthesis and growth

Publisher: CSIRO Publishing

Date: 2010

DOI: 10.1071/FP09298

Abstract: Floodwaters differ markedly in dissolved CO2, yet the effects of CO2 on submergence responses of terrestrial plants have rarely been examined. The influence of dissolved CO2 on underwater photosynthesis and growth was evaluated for three accessions of the wetland plant Hordeum marinum Huds. All three accessions tolerated complete submergence, but only when in CO2 enriched floodwater. Plants submerged for 7 days in water at air equilibrium (18 µM CO2) suffered loss of biomass, whereas those with 200 µM CO2 continued to grow. Higher underwater net photosynthesis at 200 µM CO2 increased by 2.7- to 3.2-fold sugar concentrations in roots of submerged plants, compared with at air equilibrium CO2. Leaf gas films enhancing gas exchange with floodwater, lack of a shoot elongation response conserving tissue sugars and high tissue porosity (24–31% in roots) facilitating internal O2 movement, would all contribute to submergence tolerance in H. marinum. The present study demonstrates that dissolved CO2 levels can determine submergence tolerance of terrestrial plants. So, submergence experiments should be conducted with defined CO2 concentrations and enrichment might be needed to simulate natural environments and, thus, provide relevant plant responses.

Growth responses of cool-season grain legumes to transient waterlogging

Publisher: CSIRO Publishing

Date: 2007

DOI: 10.1071/AR06330

Abstract: Transient waterlogging reduces the yield of cool-season grain legumes in several parts of the world. The tolerance of grain legumes to waterlogging may vary between and within species. This study investigated the effects of 7 days of waterlogging and subsequent recovery (10 days) on plant growth to evaluate the variation in tolerance among 7 cool-season grain legume species, in sand culture in glasshouse experiments. Additionally waterlogging tolerance of 6 faba bean genotypes was also evaluated. Tolerance to waterlogging as indicated by root and shoot growth (as % of drained controls) was ranked as follows: faba bean yellow lupin grass pea narrow-leafed lupin chickpea lentil field pea. Faba bean produced adventitious roots and aerenchyma leading to increased root porosity (9% gas volume per unit root volume). Among the 6 faba bean genotypes screened, accession 794 showed the best waterlogging tolerance, but it was also the slowest growing accession, which might have contributed to apparent tolerance (i.e. growth as % drained control). It is concluded that waterlogging tolerance in grain legumes varied between and within species, with faba bean being the most tolerant. The variation in tolerance identified within the limited set of faba bean genotypes evaluated suggests scope for further genetic improvement of tolerance in this species.

Salt tolerance in relation to elemental concentrations in leaf cell vacuoles and chloroplasts of a C

Publisher: Wiley

Date: 24-02-2022

DOI: 10.1111/PCE.14279

Abstract: Halophytes accumulate and sequester high concentrations of salt in vacuoles while maintaining lower levels of salt in the cytoplasm. The current data on cellular and subcellular partitioning of salt in halophytes are, however, limited to only a few dicotyledonous C

Erratum to: The influence of NaCl salinity and hypoxia on aspects of growth in Trifolium species

Publisher: CSIRO Publishing

Date: 2010

DOI: 10.1071/CP08123_ER

Abstract: The effects of salinity and hypoxia on growth, nutritive value, and ion relations were evaluated in 38 species of Trifolium and 3 check legume species (Trifolium fragiferum, Trifolium michelianum, and Medicago sativa) under glasshouse conditions, with the aim of identifying species that may be suitable for saline and/or waterlogged conditions. In the first set of experiments, plants were grown hydroponically at four NaCl concentrations (0, 40, 80, and 160�mm NaCl) and harvested after exposure to these treatments for 4 weeks. NaCl concentrations up to 160�mM reduced dry matter production in most species however, there were differences in salt tolerance among species, with T. argutum, T. diffusum, T. hybridum, and T. ornithopodioides performing well under the saline conditions (dry matter production was reduced by less than 20%). Concentrations of Na+ and Cl- in the shoots increased with increasing salinity levels, and species again differed in their capacity to limit the uptake of these ions. Dry matter digestibility at 0�mm ranged from 49.8% (T. palaestinum) to 74.0% (T. vesiculosum) and decreased with increasing NaCl concentrations. A second set of experiments evaluated the tolerance of Trifolium species to hypoxic conditions in the glasshouse. Shoot growth, and to a lesser extent root growth, were reduced in all Trifolium species when plants were exposed to stagnant, non-aerated conditions for 28 days, but T. michelianum, T. resupinatum, T. squamosum, T. nigrescens, T. ornithopodioides, T. salmoneum, and T. fragiferum were the least affected species. All species acclimated to the oxygen-depleted conditions by increasing the gas-filled porosity in the roots. This study has provided information that will assist in the identification of forage species for saline and/or waterlogged areas.

Root length is proxy for high-Throughput screening of waterlogging tolerance in Urochloa spp. grasses

Publisher: CSIRO Publishing

Date: 2021

DOI: 10.1071/FP20200

Abstract: C4 perennial Urochloa spp. grasses are widely planted in extensive areas in the tropics. These areas are continuously facing waterlogging events, which limits plant growth and production. However, no commercial cultivar combining excellent waterlogging tolerance with superior biomass production and nutritional quality is available. The objective of this study was to identify root traits that can be used for selecting waterlogging tolerant species of Urochloa. Root respiration, root morphological, architectural and anatomical traits were evaluated in eight contrasting Urochloa spp. genotypes grown under aerated or deoxygenated stagnant solutions. Moreover, modelling of internal aeration was used to relate differences in root traits and root growth in waterlogged soils. Increased aerenchyma formation in roots, reduced stele area and development of a fully suberised exodermis are characteristics improving internal aeration of roots and therefore determining waterlogging tolerance in these C4 forage grasses. Waterlogging-tolerant genotypes had steeper root angles and greater root lengths than the waterlogging-sensitive genotypes. In stagnant conditions, waterlogging-tolerant genotypes had a greater proportion of aerenchyma and reduced stele area in root cross-sections, had deeper roots, steeper root angle and larger root biomass, which in turn, allowed for greater shoot biomass. Total root length had the strongest positive influence on shoot dry mass and can therefore be used as proxy for selecting waterlogging tolerant Urochloa genotypes.

Flooding tolerance of forage legumes

Publisher: Oxford University Press (OUP)

Date: 20-06-2016

DOI: 10.1093/JXB/ERW239

Abstract: We review waterlogging and submergence tolerances of forage (pasture) legumes. Growth reductions from waterlogging in perennial species ranged from >50% for Medicago sativa and Trifolium pratense to 10 d) leaves suffer chlorophyll degradation, damage, and N, P, and K deficiencies. In tolerant L. corniculatus and L. tenuis, photosynthesis is maintained longer, shoot N is less affected, and shoot P can even increase during waterlogging. Species also differ in tolerance of partial and complete shoot submergence. Gaps in knowledge include anoxia tolerance of roots, N2 fixation during field waterlogging, and identification of traits conferring the ability to recover after water subsides.

Spectral detection of stress-related pigments in salt-lake succulent halophytic shrubs

Publisher: Elsevier BV

Date: 10-2016

DOI: 10.1016/J.JAG.2016.07.002

Salinity tolerance in halophytes

Publisher: Wiley

Date: 06-08-2008

DOI: 10.1111/J.1469-8137.2008.02531.X

Abstract: Contents Summary 945 I. Introduction 946 II. Growth and osmotic adjustment 946 III. Uptake and transport of monovalent ions 950 IV. Conclusions and perspectives 956 Acknowledgements 957 References 959

Root phenotypes of dwarf and “overgrowth” SLN1 barley mutants, and implications for hypoxic stress tolerance

Publisher: Elsevier BV

Date: 03-2019

DOI: 10.1016/J.JPLPH.2019.01.009

Abstract: Gibberellins are central to the regulation of plant development and growth. Action of gibberellins involves the degradation of DELLA proteins, which are negative regulators of growth. In barley (Hordeum vulgare), certain mutations affecting genes involved in gibberellin synthesis or coding for the barley DELLA protein (Sln1) confer dwarfism. Recent studies have identified new alleles of Sln1 with the capacity to revert the dwarf phenotype back to the taller phenotypes. While the effect of these overgrowth alleles on shoot phenotypes has been explored, no information is available for roots. Here, we examined aspects of the root phenotypes displayed by plants with various Sln1 gene alleles, and tested responses to growth in an O

Contrasting water relations of three coastal tree species with different exposure to salinity

Publisher: Wiley

Date: 24-02-2006

DOI: 10.1111/J.1399-3054.2006.00633.X

Improving salt tolerance of wheat and barley: future prospects

Publisher: CSIRO Publishing

Date: 2005

DOI: 10.1071/EA04162

Abstract: Cropping on saline land is restricted by the low tolerance of crops to salinity and waterlogging. Prospects for improving salt tolerance in wheat and barley include the use of: (i) intra-specific variation, (ii) variation for salt tolerance in the progenitors of these cereals, (iii) wide-hybridisation with halophytic ‘wild’ relatives (an option for wheat, but not barley), and (iv) transgenic techniques. In this review, key traits contributing to salt tolerance, and sources of variation for these within the Triticeae, are identified and recommendations for use of these traits in screening for salt tolerance are summarised. The potential of the approaches to deliver substantial improvements in salt tolerance is discussed, and the importance of adverse interactions between waterlogging and salinity are emphasised. The potential to develop new crops from the erse halophytic flora is also considered.

Radial oxygen loss from intact roots of Halophila ovalis as a function of distance behind the root tip and shoot illumination

Publisher: Elsevier BV

Date: 04-1999

DOI: 10.1016/S0304-3770(98)00126-0

Heat stress of two tropical seagrass species during low tides - impact on underwater net photosynthesis, dark respiration and diel in situ internal aeration

Publisher: Wiley

Date: 23-02-2016

DOI: 10.1111/NPH.13900

Abstract: Seagrasses grow submerged in aerated seawater but often in low O 2 sediments. Elevated temperatures and low O 2 are stress factors. Internal aeration was measured in two tropical seagrasses, Thalassia hemprichii and Enhalus acoroides , growing with extreme tides and diel temperature litudes. Temperature effects on net photosynthesis ( P N ) and dark respiration ( R D ) of leaves were evaluated. Daytime low tide was characterized by high p O 2 (54 kP a), pH (8.8) and temperature (38°C) in shallow pools. As P N was maximum at 33°C (9.1 and 7.2 μmol O 2 m −2 s −1 in T. hemprichii and E. acoroides , respectively), the high temperatures and reduced CO 2 would have diminished P N , whereas R D increased (Q 10 of 2.0–2.7) above that at 33°C (0.45 and 0.33 μmol O 2 m −2 s −1 , respectively). During night‐time low tides, O 2 declined resulting in shoot base anoxia in both species, but incoming water containing c . 20 kP a O 2 relieved the anoxia. Shoots exposed to 40°C for 4 h showed recovery of P N and R D , whereas 45°C resulted in leaf damage. These seagrasses are ‘living near the edge’, tolerant of current diel O 2 and temperature extremes, but if temperatures rise both species may be threatened in this habitat.

Root-zone hypoxia reduces growth of the tropical forage grass Urochloa humidicola in high-nutrient but not low-nutrient conditions

Publisher: Oxford University Press (OUP)

Date: 06-2019

DOI: 10.1093/AOB/MCZ071

Abstract: The perennial C4 grass Urochloa humidicola is widely planted on infertile acidic and waterlogging-prone soils of tropical America. Waterlogging results in soil anoxia, and O2 deficiency can reduce nutrient uptake by roots. Interestingly, both nutrient deficiencies and soil waterlogging can enhance root cortical cell senescence, and the increased gas-filled porosity facilitates internal aeration of roots. We tested the influence of nutrient supply and root-zone O2 on root traits, leaf nutrient concentrations and growth of U. humidicola. Plants were grown in pots in a completely randomized design under aerated or stagnant deoxygenated hydroponic conditions and six nutrient regimes, with low to high concentrations of all essential elements, for 28 d in a controlled-temperature greenhouse. The standard acid solution (SAS) used was previously designed based on infertile acidic soils of the tropical America savannas, and step increases in the concentration of SAS were used in aerated or deoxygenated 0.1 % agar solution, which mimics changes in gas composition in waterlogged soils. Measurements included shoot and root growth, root porosity, root anatomy, radial O2 loss, and leaf tissue nutrient concentrations. Shoot dry mass was reduced for plants in stagnant compared with aerated conditions at high, but not at low, levels of mineral nutrition. In low-nutrition stagnant solution, roots were shorter, of greater porosity and had smaller radial thickness of the stele. Suberized lamellae and lignified sclerenchyma, as well as a strong barrier to radial O2 loss, were documented for roots from all treatments. Leaf nutrient concentrations of K, Mg and Ca (but not N, P and S) were higher in aerated than in stagnant conditions. Under low-nutrient conditions, plant growth in stagnant solution was equal to that in aerated solution, whereas under higher-nutrient regimes growth increased but dry mass in stagnant solution was less than in aerated solution. Slow growth in low-nutrient conditions limited any further response to the low O2 treatment, and greater porosity and smaller stele size in roots would enhance internal O2 movement within roots in the nutrient-limited stagnant conditions. A constitutive barrier to radial O2 loss and aerenchyma facilitates O2 movement to the tips of roots, which presumably contributes to maintaining nutrient uptake and the tolerance of U. humidicola to low O2 in the root-zone.

Prioritisation of novel pasture species for use in water-limited agriculture: a case study of Cullen in the Western Australian wheatbelt

Publisher: Springer Science and Business Media LLC

Date: 12-05-2011

DOI: 10.1007/S10722-010-9567-3

Lotus tenuis tolerates the interactive effects of salinity and waterlogging by ‘excluding’ Na+ and Cl- from the xylem

Publisher: Oxford University Press (OUP)

Date: 23-04-2007

DOI: 10.1093/JXB/ERM102

Abstract: Salinity and waterlogging interact to reduce growth of poorly adapted species by, amongst other processes, increasing the rate of Na(+) and Cl(-) transport to shoots. Xylem concentrations of these ions were measured in sap collected using xylem-feeding spittlebugs (Philaenus spumarius) from Lotus tenuis and Lotus corniculatus in saline (NaCl) and anoxic (stagnant) treatments. In aerated NaCl solution (200 mM), L. corniculatus had 50% higher Cl(-) concentrations in the xylem and shoot compared with L. tenuis, whereas concentrations of Na(+) and K(+) did not differ between the species. In stagnant-plus-NaCl solution, xylem Cl(-) and Na(+) concentrations of L. corniculatus increased to twice those of L. tenuis. These differences in xylem ion concentrations, which were not caused by variation in transpiration between the two species, contributed to lower net accumulation of Na(+) and Cl(-) in shoots of L. tenuis, indicating that ion transport mechanisms in roots of L. tenuis were contributing to better 'exclusion' of Cl(-) and Na(+) from shoots, compared with L. corniculatus. Root porosity was also higher in L. tenuis, due to constitutive aerenchyma, than in L. corniculatus, suggesting that enhanced root aeration contributed to the maintenance of Na(+) and Cl(-) 'exclusion' in L. tenuis exposed to stagnant-plus-NaCl treatment. Lotus tenuis also had greater dry mass than L. corniculatus after 56 d in NaCl or stagnant-plus-NaCl treatment. Thus, Cl(-) 'exclusion' is a key trait contributing to salt tolerance of L. tenuis, and 'exclusion' of both Cl(-) and Na(+) from the xylem enables L. tenuis to tolerate, better than L. corniculatus, the interactive stresses of salinity and waterlogging.

Effects of waterlogging on root nodulation, respiration and formation of aerenchyma in Melilotus siculus

Publisher: Oxford University Press (OUP)

Date: 17-01-2018

DOI: 10.1093/AOB/MCX202

Regulation of Root Traits for Internal Aeration and Tolerance to Soil Waterlogging-Flooding Stress

Publisher: Oxford University Press (OUP)

Date: 08-11-2017

DOI: 10.1104/PP.17.01157

Long‐distance transport of gases in plants: a perspective on internal aeration and radial oxygen loss from roots

Publisher: Wiley

Date: 2003

DOI: 10.1046/J.1365-3040.2003.00846.X

Leaf gas films of Spartina anglica enhance rhizome and root oxygen during tidal submergence

Publisher: Wiley

Date: 08-09-2011

DOI: 10.1111/J.1365-3040.2011.02405.X

Abstract: Gas films on hydrophobic surfaces of leaves of some wetland plants can improve O(2) and CO(2) exchange when completely submerged during floods. Here we investigated the in situ aeration of rhizomes of cordgrass (Spartina anglica) during natural tidal submergence, with focus on the role of leaf gas films on underwater gas exchange. Underwater net photosynthesis was also studied in controlled laboratory experiments. In field experiments, O(2) microelectrodes were inserted into rhizomes and pO(2) measured throughout two tidal submergence events one during daylight and one during night-time. Plants had leaf gas films intact or removed. Rhizome pO(2) dropped significantly during complete submergence and most severely during night. Leaf gas films: (1) enhanced underwater photosynthesis and pO(2) in rhizomes remained above 10 kPa during submergence in light and (2) facilitated O(2) entry from the water into leaves so that rhizome pO(2) was about 5 kPa during darkness. This study is the first in situ demonstration of the beneficial effects of leaf gas films on internal aeration in a submerged wetland plant. Leaf gas films likely contribute to submergence tolerance of S. anglica and this feature is expected to also benefit other wetland plant species when submerged.

Sensitivity of chickpea and faba bean to root-zone hypoxia, elevated ethylene, and carbon dioxide

Publisher: Wiley

Date: 23-05-2019

DOI: 10.1111/PCE.13173

Abstract: During soil waterlogging, plants experience O

Microsite and litter cover effects on soil conditions and seedling recruitment in a saline agricultural system

Publisher: Springer Science and Business Media LLC

Date: 11-06-2011

DOI: 10.1007/S11104-011-0850-7

Effect of Timing and Duration of Soil Saturation on Soilborne Pythium Diseases of Common Bean (Phaseolus vulgaris)

Publisher: Scientific Societies

Date: 2015

DOI: 10.1094/PDIS-09-13-0964-RE

Abstract: Understanding combined abiotic (waterlogging) and biotic (Pythium spp.) stress resistance remains an important challenge to improving common bean (Phaseolus vulgaris) productivity in disease-prone regions with irregular but intensive rainfall patterns. This study documented the effects of timing (1, 3, 5, 7, and 9 days after sowing) and duration (3, 6, 12, and 24 h) of soil saturation (waterlogging) on d ing-off, as well as hypocotyl and root diseases of common bean caused by Pythium irregulare. There were significant effects of timing of waterlogging as well as the presence or absence of the pathogen on emergence of the three bean varieties tested namely, ‘Gourmet Delight’, ‘Brown Beauty’, and ‘Pioneer’. The interaction between time of waterlogging and variety was significant for both root and hypocotyl disease severities. In the presence of P. irregulare, waterlogging 1 day after sowing resulted in the least emergence (55.2 ± 5.6%), although plants that survived after 5 weeks had less hypocotyl and root disease (percent hypocotyl disease index [%HDI] ± standard deviation [SD] = 42.0 ± 2.1% and percent root disease index [%RDI] ± SD = 42.4 ± 2.1%, respectively) than nonwaterlogged plants (%HDI = 50.8 ± 2.1% and %RDI = 48.0 ± 2.1%, respectively). The most severe disease assessed 5 weeks after sowing occurred when plants were subjected to waterlogging 9 days after sowing (%HDI = 61.3 ± 2.1% and %RDI = 56.0 ± 2.1%). In general, both hypocotyl and root disease severity increased as the duration of waterlogging increased from 1 to 24 h, with %HDI increasing from 53.9 ± 3.2% to 70.9 ± 3.2%, while %RDI increased from 57.2 ± 1.5% to 73.7 ± 1.5%. Varieties responded differentially in terms of disease development after waterlogging, with the least hypocotyl and root disease on Gourmet Delight (%HDI = 51.4 ± 3.2 and %RDI = 60.1 ± 1.5, respectively) and greatest on Pioneer (%HDI = 66.2 ± 3.2 and %RDI = 64.9 ± 1.5, respectively). Despite being susceptible to hypocotyl and root disease, Pioneer had the greatest emergence and shoot dry weight overall among the three varieties, suggesting that this variety has a degree of tolerance to waterlogging, P. irregulare infection, and the combination of these two stresses. Although the resistance of Gourmet Delight could be exploited to breed bean varieties that exhibit less hypocotyl and root disease when waterlogging occurs, the tolerance to both P. irregulare infection and waterlogging observed for Pioneer could also be exploited to breed varieties that incur less damage from hypocotyl or root disease or waterlogging. Furthermore, this study demonstrated what appears to be independent resistance to hypocotyl versus root infection by P. irregulare, which offers an opportunity to combine resistance to both stresses to reduce the impact of d ing-off and root rot in conditions conducive for P. irregulare.

Approaches to scheduling water allocations to kikuyugrass grown on a water repellent soil in a drying-climate

Publisher: Elsevier BV

Date: 03-2020

DOI: 10.1016/J.AGWAT.2019.105957

CO2 and O-2 dynamics in leaves of aquatic plants with C-3 or CAM photosynthesis - application of a novel CO2 microsensor

Publisher: Oxford University Press (OUP)

Date: 11-06-2018

DOI: 10.1093/AOB/MCY095

Cross-tolerance for drought, heat and salinity stresses in chickpea (Cicer arietinum L.)

Publisher: Wiley

Date: 12-02-2020

DOI: 10.1111/JAC.12393

Aerenchyma Formation in Plants

Publisher: Springer Vienna

Date: 06-12-2013

DOI: 10.1007/978-3-7091-1254-0_13

Waterlogging differentially affects yield and its components in wheat, barley, rapeseed and field pea depending on the timing of occurrence

Publisher: Wiley

Date: 21-02-2020

DOI: 10.1111/JAC.12396

Underwater photosynthesis and internal aeration of submerged terrestrial wetland plants

Publisher: Springer Vienna

Date: 06-12-2014

DOI: 10.1007/978-3-7091-1254-0_16

Energetics of acclimation to NaCl by submerged, anoxic rice seedlings

Publisher: Oxford University Press (OUP)

Date: 10-2016

DOI: 10.1093/AOB/MCW189

Salinization of the soil solution decreases the further accumulation of salt in the root zone of the halophyte Atriplex nummularia Lindl. growing above shallow saline groundwater

Publisher: Wiley

Date: 19-05-2017

DOI: 10.1111/PCE.12958

Abstract: Water use by plants in landscapes with shallow saline groundwater may lead to the accumulation of salt in the root zone. We examined the accumulation of Na

Variation in salinity tolerance, early shoot mass and shoot ion concentrations within Lotus tenuis: towards a perennial pasture legume for saline land

Publisher: CSIRO Publishing

Date: 2010

DOI: 10.1071/CP09318

Abstract: Perennial legumes are needed for productive pastures in saline areas. We evaluated 40 lines of Lotus tenuis for tolerance to salinity at both germination and vegetative growth stages. Salt tolerance during the early vegetative stage was assessed in a sand-tank experiment with NaCl concentrations of 0–450 mm NaCl for 5 weeks. Most L. tenuis lines were more salt tolerant and had at least 50% lower shoot Na+ plus Cl– (% dry mass (DM)) compared with some other common pasture legumes, Medicago sativa, M. polymorpha and Trifolium subterraneum. Within L. tenuis significant variation in salt tolerance was found, with C50 values (concentrations of NaCl that decreased shoot dry matter to 50% of control) ranging from ~100 to 320 mm. Shoot concentrations of Cl–, Na+ and K+ did not always correlate with salt tolerance some tolerant lines had low shoot Na+ and Cl– (and thus better nutritive value), while others tolerated high shoot Na+ and Cl–. We also found variation within L. tenuis for salt tolerance of seeds, with lines ranging from 0 to 70% germination after recovery from a prior exposure to 800 mm NaCl for 15 days. There was no relationship between salinity tolerance of scarified seeds and subsequent growth of seedlings therefore, testing of seeds alone would not be an appropriate screening method for salt tolerance in L. tenuis. This study of 40 L. tenuis lines has shown significant genetic variation for salt tolerance within this species, and we have identified key lines with potential to be productive in saltland pasture systems.

Ethylene regulates fast apoplastic acidification and expansin A transcription during submergence‐induced petiole elongation in Rumex palustris

Publisher: Wiley

Date: 07-07-2005

DOI: 10.1111/J.1365-313X.2005.02477.X

Arabidopsis–rice–wheat gene orthologues for Na+ transport and transcript analysis in wheat–L. elongatum aneuploids under salt stress

Publisher: Springer Science and Business Media LLC

Date: 14-11-2007

DOI: 10.1007/S00438-006-0184-Y

Abstract: Lophopyrum elongatum is a wild relative of wheat that provides a source of novel genes for improvement of the salt tolerance of bread wheat. Improved Na(+) 'exclusion' is associated with salt tolerance in a wheat-L. elongatum hiploid, in which a large proportion (ca. 50%) of the improved regulation of leaf Na(+) concentrations is controlled by chromosome 3E. In this study, genes that might control Na(+) accumulation, such as for transporters responsible for Na(+) entry (HKT1) and exit (SOS1) from cells, or compartmentalisation within vacuoles (NHX1, NHX5, AVP1, AVP2) in the model plant, Arabidopsis thaliana, were targeted for comparative analyses in wheat. Putative rice orthologues were identified and characterised as a means to bridge the large evolutionary distance between genomes from the model dicot and the more complex grass species. Wheat orthologues were identified through BLAST searching to identify either FL-cDNAs or ESTs and were subsequently used to design primers to lify genomic DNA. The probable orthologous status of the wheat genes was confirmed through demonstration of similar intron-exon structure with their counterparts in Arabidopsis and rice. The majority of exons for Arabidopsis, rice and wheat orthologues of NHX1, NHX5 and SOS1 were conserved except for those at the amino and carboxy terminal ends. However, additional exons were identified in the predicted NHX1 and SOS1 genes of rice and wheat, as compared with Arabidopsis, indicating gene rearrangement events during evolution from a common ancestor. Nullisomic-tetrasomic, deletion and addition lines in wheat were used to assign gene sequences to chromosome regions in wheat and L. elongatum. Most sequences were assigned to homoeologous chromosomes, however, in some instances, such as for SOS1, genes were mapped to other unpredicted locations. Differential transcript abundance under salt stress indicated a complex pattern of expression for wheat orthologues that may regulate Na(+) accumulation in wheat lines containing chromosomes from L. elongatum. The identification of wheat orthologues to well characterized Arabidopsis genes, map locations and gene expression profiles increases our knowledge on the complex mechanisms regulating Na(+) transport in wheat and wheat-L. elongatum lines under salt stress.

Turfgrass education, research and information in Australia: history, development and implications

Publisher: International Society for Horticultural Science (ISHS)

Date: 09-2016

DOI: 10.17660/ACTAHORTIC.2016.1122.2

Waterlogging of Winter Crops at Early and Late Stages: Impacts on Leaf Physiology, Growth and Yield

Publisher: Frontiers Media SA

Date: 20-12-2018

DOI: 10.3389/FPLS.2018.01863

Variable tolerance of wetland tree species to combined salinity and waterlogging is related to regulation of ion uptake and production of organic solutes

Publisher: Wiley

Date: 26-08-2005

DOI: 10.1111/J.1469-8137.2005.01552.X

Abstract: Melaleuca cuticularis and Casuarina obesa occur in wetlands, whereas Banksia attenuata occurs in adjacent well-drained sandy soils. Salt and waterlogging tolerances in these tree species were studied, as the levels of these stresses have increased in south-western Australia. Seedlings were exposed to 0.01, 200 or 400 mm NaCl, with or without waterlogging, in a sand culture with nutrient solution for 22 d in a glasshouse. Melaleuca cuticularis and C. obesa survived all treatments, and generally maintained high rates of net photosynthesis. Banksia attenuata tolerated neither waterlogging nor salinity. Salt tolerance of M. cuticularis and C. obesa was associated with the regulation of foliar sodium (Na+), chloride (Cl-) and potassium (K+) concentrations. Under saline-waterlogged conditions, this regulation was maintained in M. cuticularis, but was reduced in C. obesa. Foliage of these two species also contained appreciable levels of compatible organic solutes: methyl proline in M. cuticularis and proline in C. obesa in both cases the concentrations increased at higher salinity. Melaleuca cuticularis formed a higher proportion of aerenchyma in adventitious roots than C. obesa, so enhanced internal root aeration in M. cuticularis might contribute to its higher tolerance of combined salinity and waterlogging.

Use of wild relatives to improve salt tolerance in wheat

Publisher: Oxford University Press (OUP)

Date: 03-2006

DOI: 10.1093/JXB/ERJ124

Abstract: There is considerable variability in salt tolerance amongst members of the Triticeae, with the tribe even containing a number of halophytes. This is a review of what is known of the differences in salt tolerance of selected species in this tribe of grasses, and the potential to use wild species to improve salt tolerance in wheat. Most investigators have concentrated on differences in ion accumulation in leaves, describing a desirable phenotype with low leaf Na+ concentration and a high K+/Na+ ratio. Little information is available on other traits (such as "tissue tolerance" of accumulated Na+ and Cl-) that might also contribute to salt tolerance. The sources of Na+ "exclusion" amongst the various genomes that make up tetraploid (AABB) durum wheat (Triticum turgidum L. ssp. durum), hexaploid (AABBDD) bread wheat (Triticum aestivum L. ssp. aestivum), and wild relatives (e.g. Aegilops spp., Thinopyrum spp., Elytrigia elongata syn. Lophopyrum elongatum, Hordeum spp.) are described. The halophytes display a capacity for Na+ "exclusion", and in some cases Cl- "exclusion", even at relatively high salinity. Significantly, it is possible to hybridize several wild species in the Triticeae with durum and bread wheat. Progenitors have been used to make synthetic hexaploids. Halophytic relatives, such as tall wheatgrass spp., have been used to produce hiploids, disomic chromosome addition and substitution lines, and recombinant lines in wheat. Ex les of improved Na+ "exclusion" and enhanced salt tolerance in various derivatives from these various hybridization programmes are given. As several sources of improved Na+ "exclusion" are now known to reside on different chromosomes in various genomes of species in the Triticeae, further work to identify the underlying mechanisms and then to pyramid the controlling genes for the various traits, that could act additively or even synergistically, might enable substantial gains in salt tolerance to be achieved.

Estimation of genetic components of variation for salt tolerance in chickpea using generation mean analysis

Publisher: Springer Science and Business Media LLC

Date: 28-07-2011

DOI: 10.1007/S10681-011-0496-9

Plant growth and physiology under heterogeneous salinity

Publisher: Springer Science and Business Media LLC

Date: 21-03-2012

DOI: 10.1007/S11104-012-1193-8

Root growth response of serradella species to aluminium in solution culture and soil

Publisher: Wiley

Date: 03-2021

DOI: 10.1111/GFS.12528

Differential responses of three coastal grassland species to seawater flooding

Publisher: Oxford University Press (OUP)

Date: 23-04-2016

DOI: 10.1093/JPE/RTW037

Tolerance and recovery of the annual pasture legumes Melilotus siculus, Trifolium michelianum and Medicago polymorpha to soil salinity, soil waterlogging and the combination of these stresses

Publisher: Springer Science and Business Media LLC

Date: 29-08-2019

DOI: 10.1007/S11104-019-04254-Z

Microarray analysis of laser-microdissected tissues indicates the biosynthesis of suberin in the outer part of roots during formation of a barrier to radial oxygen loss in rice (Oryza sativa)

Publisher: Oxford University Press (OUP)

Date: 09-06-2014

DOI: 10.1093/JXB/ERU235

Abstract: Internal aeration is crucial for root growth in waterlogged soil. A barrier to radial oxygen loss (ROL) can enhance long-distance oxygen transport via the aerenchyma to the root tip a higher oxygen concentration at the apex enables root growth into anoxic soil. The ROL barrier is formed within the outer part of roots (OPR). Suberin and/or lignin deposited in cell walls are thought to contribute to the barrier, but it is unclear which compound is the main constituent. This study describes gene expression profiles during ROL barrier formation in rice roots to determine the relative responses of suberin and/or lignin biosyntheses for the barrier. OPR tissues were isolated by laser microdissection and their transcripts were analysed by microarray. A total of 128 genes were significantly up- or downregulated in the OPR during the barrier formation. Genes associated with suberin biosynthesis were strongly upregulated, whereas genes associated with lignin biosynthesis were not. By an ab initio analysis of the promoters of the upregulated genes, the putative cis-elements that could be associated with transcription factors, WRKY, AP2/ERF, NAC, bZIP, MYB, CBT/DREB, and MADS, were elucidated. They were particularly associated with the expression of transcription factor genes containing WRKY, AP2, and MYB domains. A semiquantitative reverse-transcription PCR analysis of genes associated with suberin biosynthesis (WRKY, CYP, and GPAT) confirmed that they were highly expressed during ROL barrier formation. Overall, these results suggest that suberin is a major constituent of the ROL barrier in roots of rice.

Morphological and Physiological Responses of Rice (Oryza sativa) to Limited Phosphorus Supply in Aerated and Stagnant Solution Culture

Publisher: Oxford University Press (OUP)

Date: 22-08-2006

DOI: 10.1093/AOB/MCL194

Conditions Leading to High CO2 (>5 kPa) in Waterlogged–Flooded Soils and Possible Effects on Root Growth and Metabolism

Publisher: Oxford University Press (OUP)

Date: 27-04-2006

DOI: 10.1093/AOB/MCL076

The potential for developing fodder plants for the salt-affected areas of southern and eastern Australia: an overview

Publisher: CSIRO Publishing

Date: 2005

DOI: 10.1071/EA04020

Abstract: This paper reviews the major issues that impact upon the development of improved fodder species for saline environments across temperate Australia. It describes past and present research that has been, or is being, undertaken towards improvements in salt tolerance in forage species within Australia in relation to the principal regions where salinity occurs. It includes a discussion on the mechanisms of salt tolerance in plants. An extensive list of known or potential salt-tolerant fodder species is provided and the key opportunities for advancement within each of the 4 major forage groups: grasses, legumes, herbs and shrubs are discussed. Constraints to developing new salt and waterlogging tolerant fodder species are identified. A number of recommendations are made for research that should ensure that Australian producers have access to a new array of productive fodder species suited to saline environments.

Salinity tolerance in chickpea is associated with the ability to ‘exclude’ Na from leaf mesophyll cells

Publisher: Oxford University Press (OUP)

Date: 18-05-2019

DOI: 10.1093/JXB/ERZ241

Abstract: Salinity tolerance is associated with Na ‘exclusion’ from, or ‘tissue tolerance’ in, leaves. We investigated whether two contrasting chickpea genotypes, salt-tolerant Genesis836 and salt-sensitive Rupali, differ in leaf tissue tolerance to NaCl. We used X-ray microanalysis to evaluate cellular Na, Cl, and K concentrations in various cell types within leaflets and also in secretory trichomes of the two chickpea genotypes in relation to photosynthesis in control and saline conditions. TEM was used to assess the effects of salinity on the ultrastructure of chloroplasts. Genesis836 maintained net photosynthetic rates (A) for the 21 d of salinity treatment (60 mM NaCl), whereas A in Rupali substantially decreased after 11 d. Leaflet tissue [Na] was low in Genesis836 but had increased markedly in Rupali. In Genesis836, Na was accumulated in epidermal cells but was low in mesophyll cells, whereas in Rupali cellular [Na] was high in both cell types. The excessive accumulation of Na in mesophyll cells of Rupali corresponded to structural damage to the chloroplasts. Maintenance of photosynthesis and thus salinity tolerance in Genesis836 was associated with an ability to ‘exclude’ Na from leaflets and in particular from the photosynthetically active mesophyll cells, and to compartmentalize Na in epidermal cells.

Physical gills prevent drowning of many wetland insects, spiders and plants

Publisher: The Company of Biologists

Date: 03-2012

DOI: 10.1242/JEB.065128

Abstract: Insects, spiders and plants risk drowning in their wetland habitats. The slow diffusion of O2 can cause asphyxiation when underwater, as O2 supply cannot meet respiratory demands. Some animals and plants have found a common solution to the major challenge: how to breathe underwater with respiratory systems evolved for use in air? Hydrophobic surfaces on their bodies possess gas films that act as a ‘physical gill’ to collect O2 when underwater and thus sustain respiration. In aquatic insects, this feature rocess has been termed ‘plastron respiration’. Here, we demonstrate the similarities in function between underwater respiration of insect (Aphelocheirus aestivalis) plastrons and gas films on leaves of wetland plants (Phalaris arundinacea) and also show the importance of these physical gills by the resulting changes upon their removal. The gas films provide an enlarged gas–water interface to enhance O2 uptake underwater that is above that if only spiracles (insects) or stomata (plants) provided the gas-phase contact with the water. Body-surface gas films contribute to the survival of many insects, spiders and plants in aquatic and flood-prone environments.

Tolerance of roots to low oxygen: ‘Anoxic’ cores, the phytoglobin-nitric oxide cycle, and energy or oxygen sensing

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.JPLPH.2019.04.010

Abstract: Acclimation by plants to hypoxia and anoxia is of importance in various ecological systems, and especially for roots in waterlogged soil. We present evidence for acclimation by roots via 'anoxic' cores rather than being triggered by O

Response of Mungbean (cvs. Celera II-AU and Jade-AU) and Blackgram (cv. Onyx-AU) to Transient Waterlogging

Publisher: Frontiers Media SA

Date: 19-08-2021

DOI: 10.3389/FPLS.2021.709102

Abstract: Mungbean [ Vigna radiata (L.) Wilczek] and blackgram [ Vigna mungo (L.) Hepper] are important crops for smallholder farmers in tropical and subtropical regions. Production of both crops is affected by unexpected and increasingly frequent extreme precipitation events, which result in transient soil waterlogging. This study aimed to compare the waterlogging tolerance of mungbean and blackgram genotypes under the varying duration of waterlogging stress at germination and seedling stages. We evaluated the responses to different durations of transient waterlogging in a sandy clay loam under temperature-controlled glasshouse conditions. Waterlogging durations were 0, 1, 2, 3, 4, 5, 6, 7, and 8 days during germination and 0, 2, 4, 8, and 16 days during the seedling stage. We used two mungbean genotypes (green testa), Celera II-AU (small-seeded), and Jade-AU (large-seeded), contrasting in seed size and hypocotyl pigmentation, and a blackgram genotype (black testa), Onyx-AU. Waterlogging reduced soil redox potential, delayed or even prevented germination, decreased seedling establishment, and affected shoot and root development. In the seedlings waterlogged (WL) at 15 days after sowing (DAS), adventitious root formation and crown nodulation varied between the genotypes, and 16 days of waterlogging substantially reduced growth but did not result in plant death. Plants in soil with waterlogging for 8–16 days followed by drainage and s ling at 39 DAS had reduced shoot and root dry mass by 60–65% in mungbean and 40% in blackgram compared with continuously drained controls, due at least in part to fewer lateral roots. Soil plant analysis development (SPAD) chlorophyll content was also reduced. Onyx-AU, a blackgram genotype, was more tolerant to transient waterlogging than Jade-AU and Celera II-AU in both growth stages. Of the two mungbean genotypes, Celera II-AU had a greater seedling establishment than Jade-AU post waterlogging imposed at sowing. In contrast, Jade-AU had more plant biomass and greater recovery growth than Celera II-AU after waterlogging and recovery during the seedling stage. Both species were delayed in emergence in response to the shorter periods of transient waterlogging at germination, and with the longer waterlogging germination and emergence failed, whereas at the seedling stage both showed adaptation by the formation of adventitious roots.

Leaf gas films delay salt entry and enhance underwater photosynthesis and internal aeration of M elilotus siculus submerged in saline water

Publisher: Wiley

Date: 14-02-2014

DOI: 10.1111/PCE.12269

Abstract: A combination of flooding and salinity is detrimental to most plants. We studied tolerance of complete submergence in saline water for Melilotus siculus, an annual legume with superhydrophobic leaf surfaces that retain gas films when under water. M. siculus survived complete submergence of 1 week at low salinity (up to 50 mol m(-3) NaCl), but did not recover following de-submergence from 100 mol m(-3) NaCl. The leaf gas films protected against direct salt ingress into the leaves when submerged in saline water, enabling underwater photosynthesis even after 3 d of complete submergence. By contrast, leaves with the gas films experimentally removed suffered from substantial Na(+) and Cl(-) intrusion and lost the capacity for underwater photosynthesis. Similarly, plants in saline water and without gas films lost more K(+) than those with intact gas films. This study has demonstrated that leaf gas films reduce Na(+) and Cl(-) ingress into leaves when submerged by saline water - the thin gas layer physically separates the floodwater from the leaf surface. This feature aids survival of plants exposed to short-term saline submergence, as well as the previously recognized beneficial effects of gas exchange under water.

Assessment of O₂ diffusivity across the barrier to radial O₂ loss in adventitious roots of Hordeum marinum

Publisher: Wiley

Date: 28-06-2008

DOI: 10.1111/J.1469-8137.2008.02467.X

Abstract: The subapical regions of wetland plant roots can develop a barrier to radial O2 loss (ROL), but barrier resistance has rarely been quantified in terms of its O2 diffusivity. Barrier resistance in adventitious roots of the waterlogging-tolerant Hordeum marinum was assessed from measurements of ROL using cylindrical platinum electrodes while either varying shoot O2 partial pressures or cooling the rooting medium. Anatomical features were examined using fluorescence microscopy. When grown in stagnant agar nutrient solution, a barrier to ROL was induced over the basal half of 100-120-mm-long roots. Autofluorescence in hypodermal cell walls indicated that putative suberin deposition was coincident with barrier expression. Root cooling revealed a significant respiratory component in barrier resistance. Eliminating the respiration effect by manipulating shoot O2 partial pressures revealed an O2 diffusivity for the barrier of 5.96 x 10(-7) cm2 s(-1), 96% less than that at the apex, which was > or = 1.59 x 10(-5) cm2 s(-1). It is concluded that the ROL barrier is a manifestation of two components acting synergistically: a physical resistance caused principally by secondary cell-wall deposits in the outer hypodermal layer and respiratory activity in the hypodermal/epidermal layers with physical resistance being the dominant component.

A comparison of NH₄⁺ and NO₃^– net fluxes along roots of rice and maize

Publisher: Wiley

Date: 02-1998

DOI: 10.1046/J.1365-3040.1998.00261.X

Root porosity and oxygen movement in waterlogging‐tolerant Trifolium tomentosum and ‐intolerant Trifolium glomeratum

Publisher: Wiley

Date: 09-09-1999

DOI: 10.1046/J.1365-3040.1999.00472.X

Morphology, Anatomy and Histochemistry of Salicornioideae (Chenopodiaceae) Fruits and Seeds

Publisher: Oxford University Press (OUP)

Date: 10-03-2005

DOI: 10.1093/AOB/MCI101

Protein synthesis by rice coleoptiles during prolonged anoxia: Implications for glycolysis, growth and energy utilization

Publisher: Oxford University Press (OUP)

Date: 18-07-2005

DOI: 10.1093/AOB/MCI222

Growth of tomato and an ABA-deficient mutant (sitiens) under saline conditions

Publisher: Wiley

Date: 20-12-2003

DOI: 10.1034/J.1399-3054.2003.1170107.X

Development of wheat–Lophopyrum elongatum recombinant lines for enhanced sodium ‘exclusion’ during salinity stress

Publisher: Springer Science and Business Media LLC

Date: 09-2009

DOI: 10.1007/S00122-009-1136-9

Abstract: Lophopyrum elongatum (tall wheatgrass), a wild relative of wheat, can be used as a source of novel genes for improving salt tolerance of bread wheat. Sodium 'exclusion' is a major physiological mechanism for salt tolerance in a wheat-tall wheatgrass hiploid, and a large proportion ( approximately 50%) for reduced Na(+) accumulation in the Xag leaf, as compared to wheat, was earlier shown to be contributed by genetic effects from substitution of chromosome 3E from tall wheatgrass for wheat chromosomes 3A and 3D. Homoeologous recombination between 3E and wheat chromosomes 3A and 3D was induced using the ph1b mutant, and putative recombinants were identified as having SSR markers specific for tall wheatgrass loci. As many as 14 recombinants with smaller segments of tall wheatgrass chromatin were identified and low-resolution breakpoint analysis was achieved using wheat SSR loci. Seven recombinants were identified to have leaf Na+ concentrations similar to those in 3E(3A) or 3E(3D) substitution lines, when grown in 200 mM NaCl in nutrient solution. Phenotypic analysis identified recombinants with introgressions at the distal end on the long arm of homoeologous group 3 chromosomes being responsible for Na(+) 'exclusion'. A total of 55 wheat SSR markers mapped to the long arm of homoeologous group 3 markers by genetic and deletion bin mapping were used for high resolution of wheat-tall wheatgrass chromosomal breakpoints in selected recombinants. Molecular marker analysis and genomic in situ hybridisation confirmed the 524-568 recombinant line as containing the smallest introgression of tall wheatgrass chromatin on the distal end of the long arm of wheat chromosome 3A and identified this line as suitable for developing wheat germplasm with Na(+) 'exclusion'.

Growth and ion relatons in response to combined salinity and waterlogging in the perennial forage legumes Lotus corniculatus and Lotus tenuis

Publisher: Springer Science and Business Media LLC

Date: 11-11-2006

DOI: 10.1007/S11104-006-9146-8

Interactive effects of salinity, nitrogen and sulphur on the organic solutes inSpartina alternifloraleaf blades

Publisher: Oxford University Press (OUP)

Date: 1996

DOI: 10.1093/JXB/47.3.369

Efficient use of energy in anoxia‐tolerant plants with focus on germinating rice seedlings

Publisher: Wiley

Date: 04-12-2014

DOI: 10.1111/NPH.13173

Abstract: Anoxia tolerance in plants is distinguished by direction of the sparse supply of energy to processes crucial to cell maintenance and sometimes to growth, as in rice seedlings. In anoxic rice coleoptiles energy is used to synthesise proteins, take up K + , synthesise cell walls and lipids, and in cell maintenance. Maintenance of electrochemical H + gradients across the tonoplast and plasma membrane is crucial for solute compartmentation and thus survival. These gradients sustain some H + ‐solute cotransport and regulate cytoplasmic pH . Pyrophosphate (PP i ), the alternative energy donor to ATP , allows direction of energy to the vacuolar H + ‐PP i ase, sustaining H + gradients across the tonoplast. When energy production is critically low, operation of a biochemical pH stat allows H + ‐solute cotransport across plasma membranes to continue for at least for 18 h. In active (e.g. growing) cells, PP i produced during substantial polymer synthesis allows conversion of PP i to ATP by PP i ‐phosphofructokinase (PFK). In quiescent cells with little polymer synthesis and associated PP i formation, the PP i required by the vacuolar H + ‐PP i ase and UDPG pyrophosphorylase involved in sucrose mobilisation via sucrose synthase might be produced by conversion of ATP to PP i through reversible glycolytic enzymes, presumably pyruvate orthophosphate dikinase. These hypotheses need testing with species characterised by contrasting anoxia tolerance. Contents Summary 36 I. Introduction 36 II. PP i ‐dependent enzymes as a key adaptation to an energy crisis, enabling survival and growth in anoxia 37 III. Mechanisms of survival during an energy crisis: that is, plant quiescence during anoxia with no growth and acclimated cells in anoxia 44 IV. Energy expenditure during growth under anoxia 49 V. Conclusions on mechanisms of anoxia tolerance 53 Acknowledgements 54 References 55

Tolerance of combined submergence and salinity in the halophytic stem-succulent Tecticornia pergranulata

Publisher: Oxford University Press (OUP)

Date: 25-07-2009

DOI: 10.1093/AOB/MCN120

Responses of rice to Fe2+ in aerated and stagnant conditions: growth, root porosity and radial oxygen loss barrier

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/FP13359

Abstract: Lowland rice (Oryza sativa L.) encounters flooded soils that are anaerobic and chemically reduced. Exposure of the roots to high soil Fe2+ concentrations can result in toxicity. Internal aeration delivering O2 to submerged roots via the aerenchyma is well understood, but the effect of Fe2+ on O2 transport in roots is less studied. We aimed to evaluate the effects of Fe2+ on growth and root aeration. O. sativa var. Amaroo was grown in aerobic and deoxygenated solutions with 0 mM, 0.18 mM, 0.36 mM, 0.54 mM or 0.72 mM Fe2+ using FeSO4.7H2O and a control with 0.05 mM Fe-EDTA. The treatments were imposed on 14-day-old plants (28–30 days old when harvested). Dry mass, shoot Fe concentration, root porosity and patterns of radial O2 loss (ROL) along roots were determined. In the aerobic solution, where Fe2+ was oxidised in the bulk medium, root dry mass increased with higher Fe2+ this was not the case in stagnant solutions, which had no significant root growth response, although Fe oxidation near the root surface was visible as a precipitate. In the highest Fe2+ treatment, shoot Fe concentrations in aerobic (667 mg kg–1) and stagnant (433 mg kg–1) solutions were below the level for toxicity (700 mg kg–1). Rice responded to high Fe2+ in aerobic conditions by increasing root porosity and inducing strong barriers to ROL. In stagnant conditions, root porosity was already high and the ROL barrier induced, so these root aeration traits were not further influenced by the Fe2+ concentrations applied.

Defining the waterlogging tolerance of Ornithopus spp. for the temperate pasture zone of southern Australia

Publisher: CSIRO Publishing

Date: 2020

DOI: 10.1071/CP19491

Abstract: Increasing the area sown to Ornithopus spp. (serradella) can reduce overall fertiliser requirements in Australian permanent pastures owing to their greater nutrient-acquisition efficiency than that of more widely used pasture legumes such as Trifolium spp. However, uncertainty regarding waterlogging tolerance of Ornithopus spp. may restrict their adoption in the high-rainfall zone of southern Australia. The waterlogging tolerance of cultivars and accessions of three species of Ornithopus (O. compressus, O. sativus and O. pinnatus) was determined by comparing root and shoot growth of plants in deoxygenated, stagnant agar nutrient solution (simulated waterlogging) with growth in aerated nutrient solution. The responses were benchmarked against the known waterlogging-tolerant pasture legume Trifolium michelianum. All Ornithopus cultivars were highly impacted by the deoxygenated stagnant treatment, including those of the anecdotally waterlogging-tolerant O. pinnatus. The 14-day stagnant treatment reduced root dry mass by 32–62% and relative growth rate (RGR) of roots by 36–73%. At the same time, root porosity increased from 1.4% to 8.8%. Following a 14-day recovery period, during which plants were returned to aerated nutrient solution, Ornithopus spp. failed to increase their shoot RGR (particularly for O. sativus cultivars) however, root RGR returned to that of the aerated controls. The stagnant conditions inhibited transport of potassium (K+) to the shoots in all species, as evidenced by lower shoot tissue K+ concentrations, with O. compressus and O. sativus most adversely affected (45% and 48% of the tissue concentration of aerated control plants). We conclude that the suggested area for Ornithopus spp. adaptation should not preclude areas of high rainfall because they have root adaptations that would assist them in coping with transient water excess however, soil types and surface profiles conducive to long-term waterlogging should be avoided to negate significant productivity losses.

Global patterns of the leaf economics spectrum in wetlands

Publisher: Springer Science and Business Media LLC

Date: 09-09-2020

DOI: 10.1038/S41467-020-18354-3

Abstract: The leaf economics spectrum (LES) describes consistent correlations among a variety of leaf traits that reflect a gradient from conservative to acquisitive plant strategies. So far, whether the LES holds in wetland plants at a global scale has been unclear. Using data on 365 wetland species from 151 studies, we find that wetland plants in general show a shift within trait space along the same common slope as observed in non-wetland plants, with lower leaf mass per area, higher leaf nitrogen and phosphorus, faster photosynthetic rates, and shorter leaf life span compared to non-wetland plants. We conclude that wetland plants tend to cluster at the acquisitive end of the LES. The presented global quantifications of the LES in wetland plants enhance our understanding of wetland plant strategies in terms of resources acquisition and allocation, and provide a stepping-stone to developing trait-based approaches for wetland ecology.

Improvement of salt and waterlogging tolerance in wheat: comparative physiology of Hordeum marinum-Triticum aestivum amphiploids with their H. marinum and wheat parents

Publisher: CSIRO Publishing

Date: 2013

DOI: 10.1071/FP12385

Abstract: Hordeum marinum Huds. is a waterlogging-tolerant halophyte that has been hybridised with bread wheat (Triticum aestivum L.) to produce an hiploid containing both genomes. This study tested the hypothesis that traits associated with waterlogging and salinity tolerances would be expressed in H. marinum-wheat hiploids. Four H. marinum accessions were used as parents to produce hiploids with Chinese Spring wheat, and their responses to hypoxic and 200 mM NaCl were evaluated. Relative growth rate (RGR) in the hypoxic-saline treatment was better maintained in the hiploids (58–71% of controls) than in wheat (56% of control), but the hiploids were more affected than H. marinum (68–97% of controls). In hypoxic-saline conditions, leaf Na+ concentrations in the hiploids were lower than in wheat (30–41% lower) but were 39–47% higher than in the H. marinum parents. A strong barrier to radial oxygen loss formed in basal root zones under hypoxic conditions in two H. marinum accessions this barrier was moderate in the hiploids, absent in wheat, and was weaker for the hypoxic-saline treatment. Porosity of adventitious roots increased with the hypoxic treatments values were 24–38% in H. marinum, 16–27% in the hiploids and 16% in wheat. Overall, the hiploids showed greater salt and waterlogging tolerances than wheat, demonstrating the expression of relevant traits from H. marinum in the hiploids.

Photosynthesis in aquatic adventitious roots of the halophytic stem-succulent Tecticornia pergranulata (formerly Halosarcia pergranulata)

Publisher: Wiley

Date: 08-04-2008

DOI: 10.1111/J.1365-3040.2008.01813.X

Abstract: In flood-tolerant species, a common response to inundation is growth of adventitious roots into the water column. The capacity for these roots to become photosynthetically active has received scant attention. The experiments presented here show the aquatic adventitious roots of the flood-tolerant, halophytic stem-succulent, Tecticornia pergranulata (subfamily Salicornioideae, Chenopodiaceae) are photosynthetic and quantify for the first time the photosynthetic capacity of aquatic roots for a terrestrial species. Fluorescence microscopy was used to determine the presence of chloroplasts within cells of aquatic roots. Net O(2) production by excised aquatic roots, when underwater, was measured with varying light and CO(2) regimes the apparent maximum capacity (P(max)) for underwater net photosynthesis in aquatic roots was 0.45 micromol O(2) m(-2) s(-1). The photosynthetic potential of these roots was supported by the immunolocalization of PsbA, the major protein of photosystem II, and ribulose-1-5-bisphosphate carboxylase/oxygenase (Rubisco) in root protein extracts. Chlorophyllous aquatic roots of T. pergranulata are photosynthetically active, and such activity is a previously unrecognized source of O(2), and potentially carbohydrates, in flooded and submerged plants.

Tissue tolerance: an essential but elusive trait for salt-tolerant crops

Publisher: CSIRO Publishing

Date: 2016

DOI: 10.1071/FP16187

Abstract: For a plant to persist in saline soil, osmotic adjustment of all plant cells is essential. The more salt-tolerant species accumulate Na+ and Cl– to concentrations in leaves and roots that are similar to the external solution, thus allowing energy-efficient osmotic adjustment. Adverse effects of Na+ and Cl– on metabolism must be avoided, resulting in a situation known as ‘tissue tolerance’. The strategy of sequestering Na+ and Cl– in vacuoles and keeping concentrations low in the cytoplasm is an important contributor to tissue tolerance. Although there are clear differences between species in the ability to accommodate these ions in their leaves, it remains unknown whether there is genetic variation in this ability within a species. This viewpoint considers the concept of tissue tolerance, and how to measure it. Four conclusions are drawn: (1) osmotic adjustment is inseparable from the trait of tissue tolerance (2) energy-efficient osmotic adjustment should involve ions and only minimal organic solutes (3) screening methods should focus on measuring tolerance, not injury and (4) high-throughput protocols that avoid the need for control plants and multiple Na+ or Cl– measurements should be developed. We present guidelines to identify useful genetic variation in tissue tolerance that can be harnessed for plant breeding of salt tolerance.

The influence of NaCl salinity and hypoxia on aspects of growth in Trifolium species

Publisher: CSIRO Publishing

Date: 2009

DOI: 10.1071/CP08123

Abstract: The effects of salinity and hypoxia on growth, nutritive value, and ion relations were evaluated in 38 species of Trifolium and 3 check legume species (Trifolium fragiferum, Trifolium michelianum, and Medicago sativa) under glasshouse conditions, with the aim of identifying species that may be suitable for saline and/or waterlogged conditions. In the first set of experiments, plants were grown hydroponically at four NaCl concentrations (0, 40, 80, and 160 mm NaCl) and harvested after exposure to these treatments for 4 weeks. NaCl concentrations up to 160 mm reduced dry matter production in most species however, there were differences in salt tolerance among species, with T. argutum, T. diffusum, T. hybridum, and T. ornithopodioides performing well under the saline conditions (dry matter production was reduced by less than 20%). Concentrations of Na+ and Cl− in the shoots increased with increasing salinity levels, and species again differed in their capacity to limit the uptake of these ions. Dry matter digestibility at 0 mm ranged from 49.8% (T. palaestinum) to 74.0% (T. vesiculosum) and decreased with increasing NaCl concentrations. A second set of experiments evaluated the tolerance of Trifolium species to hypoxic conditions in the glasshouse. Shoot growth, and to a lesser extent root growth, were reduced in all Trifolium species when plants were exposed to stagnant, non-aerated conditions for 28 days, but T. michelianum, T. resupinatum, T. squamosum, T. nigrescens, T. ornithopodioides, T. salmoneum, and T. fragiferum were the least affected species. All species acclimated to the oxygen-depleted conditions by increasing the gas-filled porosity in the roots. This study has provided information that will assist in the identification of forage species for saline and/or waterlogged areas.

Hydraulic redistribution: limitations for plants in saline soils

Publisher: Wiley

Date: 07-08-2017

DOI: 10.1111/PCE.13020

Abstract: Hydraulic redistribution (HR), the movement of water from wet to dry patches in the soil via roots, occurs in different ecosystems and plant species. By extension of the principle that HR is driven by gradients in soil water potential, HR has been proposed to occur for plants in saline soils. Despite the inherent spatial patchiness and salinity gradients in these soils, the lack of direct evidence of HR in response to osmotic gradients prompted us to ask the question: are there physical or physiological constraints to HR for plants in saline environments? We propose that build-up of ions in the root xylem sap and in the leaf apoplast, with the latter resulting in a large predawn disequilibrium of water potential in shoots compared with roots and soil, would both impede HR. We present a conceptual model that illustrates how processes in root systems in heterogeneous salinity with water potential gradients, even if equal to those in non-saline soils, will experience a d ened magnitude of water potential gradients in the soil-plant continuum, minimizing or preventing HR. Finally, we provide an outlook for understanding the relevance of HR for plants in saline environments by addressing key research questions on plant salinity tolerance.

Diel O2 Dynamics in Partially and Completely Submerged Deepwater Rice: Leaf Gas Films Enhance Internodal O2 Status, Influence Gene Expression and Accelerate Stem Elongation for ‘Snorkelling’ during Su

Publisher: Oxford University Press (OUP)

Date: 22-01-2019

DOI: 10.1093/PCP/PCZ009

Abstract: Deepwater rice has a remarkable shoot elongation response to partial submergence. Shoot elongation to maintain air-contact enables 'snorkelling' of O2 to submerged organs. Previous research has focused on partial submergence of deepwater rice. We tested the hypothesis that leaf gas films enhance internode O2 status and stem elongation of deepwater rice when completely submerged. Diel patterns of O2 partial pressure (pO2) were measured in internodes of deepwater rice when partially or completely submerged, and with or without gas films on leaves, for the completely submerged plants. We also took measurements for paddy rice. Deepwater rice elongated during complete submergence and the shoot tops emerged. Leaf gas films improved O2 entry during the night, preventing anoxia in stems, which is of importance for elongation of the submerged shoots. Expressions of O2 deprivation inducible genes were upregulated in completely submerged plants during the night, and more so when gas films were removed from the leaves. Diel O2 dynamics showed similar patterns in paddy and deepwater rice. We demonstrated that shoot tops in air enabled 'snorkelling' and increased O2 in internodes of both rice ecotypes however, 'snorkelling' was achieved only by rapid shoot elongation by deepwater rice, but not by paddy rice.

Root aeration via aerenchymatous phellem: three‐dimensional micro‐imaging and radial O₂ profiles in Melilotus siculus

Publisher: Wiley

Date: 26-10-2011

DOI: 10.1111/J.1469-8137.2011.03934.X

Abstract: • Internal root aeration enables waterlogging-tolerant species to grow in anoxic soil. Secondary aerenchyma, in the form of aerenchymatous phellem, is of importance to root aeration in some dicotyledonous species. Little is known about this type of aerenchyma in comparison with primary aerenchyma. • Micro-computed tomography was employed to visualize, in three dimensions, the microstructure of the aerenchymatous phellem in roots of Melilotus siculus. Tissue porosity and respiration were also measured for phellem and stelar tissues. A multiscale, three-dimensional, diffusion-respiration model compared the predicted O(2) profiles in roots with those measured using O(2) microelectrodes. • Micro-computed tomography confirmed the measured high porosity of aerenchymatous phellem (44-54%) and the low porosity of stele (2-5%) A network of connected gas spaces existed in the phellem, but not within the stele. O(2) partial pressures were high in the phellem, but fell below the detection limit in the thicker upper part of the stele, consistent with the poorly connected low porosity and high respiratory demand. • The presented model integrates and validates micro-computed tomography with measured radial O(2) profiles for roots with aerenchymatous phellem, confirming the existence of near-anoxic conditions at the centre of the stele in the basal parts of the root, coupled with only hypoxic conditions towards the apex.

Shoot atmospheric contact is of little importance to aeration of deeper portions of the wetland plant Meionectes brownii; submerged organs mainly acquire O2 from the water column or produce it endogenously in underwater photosynthesis

Publisher: Wiley

Date: 19-07-2013

DOI: 10.1111/J.1365-3040.2012.02568.X

Abstract: Partial shoot submergence is considered less stressful than complete submergence of plants, as aerial contact allows gas exchange with the atmosphere. In situ microelectrode studies of the wetland plant Meionectes brownii showed that O(2) dynamics in the submerged stems and aquatic roots of partially submerged plants were similar to those of completely submerged plants, with internal O(2) concentrations in both organs dropping to less than 5 kPa by dawn regardless of submergence level. The anatomy at the nodes and the relationship between tissue porosity and rates of O(2) diffusion through stems were studied. Stem internodes contained aerenchyma and had mean gas space area of 17.7% per cross section, whereas nodes had 8.2%, but nodal porosity was highly variable, some nodes had very low porosity or were completely occluded (ca. 23% of nodes s led). The cumulative effect of these low porosity nodes would have impeded internal O(2) movement down stems. Therefore, regardless of the presence of an aerial connection, the deeper portions of submerged organs sourced most of their O(2) via inwards diffusion from the water column during the night, and endogenous production in underwater photosynthesis during the daytime.

Waterlogging tolerance of grass pea (Lathyrus sativus L.) at germination related to country of origin

Publisher: Cambridge University Press (CUP)

Date: 12-2020

DOI: 10.1017/S0014479720000356

Abstract: Grass pea ( Lathyrus sativus L.) has a Mediterranean origin and was spread to Western Europe, Africa and South Asia. Over time, this grain legume crop has become important in South Asia, where it is often affected by waterlogging at germination. Therefore, varieties with waterlogging tolerance of seeds at germination are needed. This study evaluated waterlogging tolerance in a grass pea ersity panel. First, morpho-agronomic traits of 53 grass pea genotypes from 7 erse countries (Afghanistan, Australia, Bangladesh, Cyprus, Ethiopia, Greece and Pakistan) were measured in a glasshouse. Seeds of the collection were then sown into waterlogged soil for 6 days and is subsequently drained for 8 days. Finally, representative genotypes from each country of origin of the three survival patterns (described below) were then tested to identify the effect of seed priming on germination and seedling growth in waterlogged soil. Canonical analysis of six traits (seed weight, pod length, pod width, flowering time, time to maturity and seedling survival) showed that genotypes from Bangladesh and Ethiopia were similar. There was a significant variation amongst genotypes in waterlogging tolerance. Genotypes from Bangladesh and Ethiopia showed the highest percent seedling survival (54% and 47%), with an ability to germinate under waterlogging and then maintain growth from the first day of draining to the final s ling (Pattern 1). In contrast, genotypes from other origins either germinated during waterlogging, but did not survive during drainage (Pattern 2) or failed to germinate and had low seedling survival during waterlogging and drainage (Pattern 3). Priming seeds reduced seedling survival in grass pea. Despite Mediterranean origin, specific ecotypes of grass pea with greater waterlogging tolerance under warm wet conditions have been favoured in Bangladesh and Ethiopia where adaptation to extreme precipitation events at germination and seedling survival upon soil drainage is critical for successful crops.

A major locus involved in the formation of the radial oxygen loss barrier in adventitious roots of teosinte Zea nicaraguensis is located on the short‐arm of chromosome 3

Publisher: Wiley

Date: 04-01-2017

DOI: 10.1111/PCE.12849

Abstract: A radial oxygen loss (ROL) barrier in roots of waterlogging-tolerant plants promotes oxygen movement via aerenchyma to the root tip, and impedes soil phytotoxin entry. The molecular mechanism and genetic regulation of ROL barrier formation are largely unknown. Zea nicaraguensis, a waterlogging-tolerant wild relative of maize (Zea mays ssp. mays), forms a tight ROL barrier in its roots when waterlogged. We used Z. nicaraguensis chromosome segment introgression lines (ILs) in maize (inbred line Mi29) to elucidate the chromosomal region involved in regulating root ROL barrier formation. A segment of the short-arm of chromosome 3 of Z. nicaraguensis conferred ROL barrier formation in the genetic background of maize. This chromosome segment also decreased apoplastic solute permeability across the hypodermis/exodermis. However, the IL and maize were similar for suberin staining in the hypodermis/exodermis at 40 mm and further behind the root tip. Z. nicaraguensis contained suberin in the hypodermis/exodermis at 20 mm and lignin at the epidermis. The IL with ROL barrier, however, did not contain lignin in the epidermis. Discovery of the Z. nicaraguensis chromosomal region responsible for root ROL barrier formation has improved knowledge of this trait and is an important step towards improvement of waterlogging tolerance in maize.

Underwater photosynthesis of submerged plants - recent advances and methods

Publisher: Frontiers Media SA

Date: 2013

DOI: 10.3389/FPLS.2013.00140

Salt tolerance in the Halophyte Halosarcia pergranulata subsp. pergranulata

Publisher: Oxford University Press (OUP)

Date: 03-1999

DOI: 10.1006/ANBO.1998.0812

Drivers of plant traits that allow survival in wetlands

Publisher: Wiley

Date: 21-02-2020

DOI: 10.1111/1365-2435.13541

Waterlogging tolerance among a diverse range of Trifolium accessions is related to root porosity, lateral root formation and 'aerotropic rooting'.

Publisher: Oxford University Press (OUP)

Date: 10-2001

DOI: 10.1006/ANBO.2001.1506

A perspective on underwater photosynthesis in submerged terrestrial wetland plants

Publisher: Oxford University Press (OUP)

Date: 2011

DOI: 10.1093/AOBPLA/PLR030

Interactive effects of Ca2+ and NaCl salinity on the ionic relations and proline accumulation in the primary root tip of Sorghum bicolor

Publisher: Wiley

Date: 07-1996

DOI: 10.1034/J.1399-3054.1996.970301.X

Response and Adaptation by Plants to Flooding Stress

Publisher: Oxford University Press (OUP)

Date: 09-2005

DOI: 10.1093/AOB/MCI205

Abstract: Stress on plants imposed by flooding of the soil and deeper submergence constitutes one of the major abiotic constraints on growth, species' distribution and agricultural productivity. Flooding stress is also a strong driver of adaptive evolution. This has resulted in a wide range of biochemical, molecular and morphological adaptations that sanction growth and reproductive success under episodic or permanently flooded conditions that are highly damaging to the majority of plant species. However, even seemingly poorly adapted species possess some short-term resilience that is important for overall success of these plants in various habitats. The papers contained in this Special Issue address these topics and emphasize molecular, biochemical and developmental processes that impact on flooding tolerance. Most of the articles are based on lectures given to the 8th Conference of the International Society for Plant Anaerobiosis (ISPA), held at the University of Western Australia, Perth, 20-24 September, 2004. Reviews and research papers are presented from the leading laboratories currently working on plant responses to flooding stress.

Oxygen dynamics in a salt-marsh soil and in Suaeda maritima during tidal submergence

Publisher: Elsevier BV

Date: 08-2013

DOI: 10.1016/J.ENVEXPBOT.2012.07.002

Aquatic adventitious roots of the wetland plant Meionectes brownii can photosynthesize: implications for root function during flooding

Publisher: Wiley

Date: 09-11-2011

DOI: 10.1111/J.1469-8137.2010.03524.X

Abstract: • Many wetland plants produce aquatic adventitious roots from submerged stems. Aquatic roots can form chloroplasts, potentially producing endogenous carbon and oxygen. Here, aquatic root photosynthesis was evaluated in the wetland plant Meionectes brownii, which grows extensive stem-borne aquatic roots during submergence. • Underwater photosynthetic light and CO(2) response curves were determined for aquatic-adapted leaves, stems and aquatic roots of M. brownii. Oxygen microelectrode and (14)CO(2)-uptake experiments determined shoot inputs of O(2) and photosynthate into aquatic roots. • Aquatic adventitious roots contain a complete photosynthetic pathway. Underwater photosynthetic rates are similar to those of stems, with a maximum net photosynthetic rate (P(max)) of 0.38 μmol O(2) m(-2) s(-1) however, this is c. 30-fold lower than that of aquatic-adapted leaves. Under saturating light with 300 mmol m(-3) dissolved CO(2), aquatic roots fix carbon at 0.016 μmol CO(2) g(-1) DM s(-1). Illuminated aquatic roots do not rely on exogenous inputs of O(2). • The photosynthetic ability of aquatic roots presumably offers an advantage to submerged M. brownii as aquatic roots, unlike sediment roots, need little O(2) and carbohydrate inputs from the shoot when illuminated.

Intermittent anoxia induces oxidative stress in wheat seminal roots: assessment of the antioxidant defence system, lipid peroxidation and tissue solutes

Publisher: CSIRO Publishing

Date: 2005

DOI: 10.1071/FP04194

Abstract: The effects of continuous and intermittent anoxia on components of the antioxidant defence system were evaluated in the expanded zones of wheat seedling roots. Intermittent anoxia caused oxidative stress (measured by the proportion of reduced glutathione) after three cycles of anoxia–aeration. The concentration of glutathione and activities of glutathione reductase (GR) and catalase (CAT) were decreased by 50% under both continuous and intermittent anoxia. Ascorbate peroxidase (APX) activity was unaffected by anoxia but stimulated almost 2-fold during the aerated periods of intermittent anoxia. Superoxide dismutase activity was decreased by 20% under continuous anoxia but ultimately returned to aerated activities under intermittent anoxia. Membrane damage appeared to be negligible or reversible, as K+ concentrations recovered to original levels under intermittent anoxia and there was no increase in terminal lipid peroxidation products. Addition of 5 mm exogenous ascorbate to intermittently anoxic roots prevented oxidative stress and avoided the decreases in glutathione, GR and CAT. Therefore, it is likely that the oxidative stress resulted from inadequate levels of, or damage to, these two enzymes.

Leaf gas films, underwater photosynthesis and plant species distributions in a flood gradient

Publisher: Wiley

Date: 12-05-2016

DOI: 10.1111/PCE.12717

Abstract: Traits for survival during flooding of terrestrial plants include stimulation or inhibition of shoot elongation, aerenchyma formation and efficient gas exchange. Leaf gas films form on superhydrophobic cuticles during submergence and enhance underwater gas exchange. The main hypothesis tested was that the presence of leaf gas films influences the distribution of plant species along a natural flood gradient. We conducted laboratory experiments and field observations on species distributed along a natural flood gradient. We measured presence or absence of leaf gas films and specific leaf area of 95 species. We also measured, gas film retention time during submergence and underwater net photosynthesis and dark respiration of 25 target species. The presence of a leaf gas film was inversely correlated to flood frequency and duration and reached a maximum value of 80% of the species in the rarely flooded locations. This relationship was primarily driven by grasses that all, independently of their field location along the flood gradient, possess gas films when submerged. Although the present study and earlier experiments have shown that leaf gas films enhance gas exchange of submerged plants, the ability of species to form leaf gas films did not show the hypothesized relationship with species composition along the flood gradient.