ORCID Profile
0000-0003-2455-1643
Current Organisation
University of Adelaide
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Plant Biology | Plant Physiology | Plant Physiology | Plant Cell and Molecular Biology | Membrane Biology | Crop and Pasture Production | Biochemistry and Cell Biology | Plant Biochemistry And Physiology | Plant Nutrition | Horticultural Production | Crop and Pasture Biochemistry and Physiology | Cell Metabolism | Oenology and Viticulture | Oenology And Viticulture | Gene Expression | Wine Chemistry and Wine Sensory Science | Genetics | Characterisation Of Macromolecules | Plant Improvement (Selection, Breeding And Genetic Engineering) | Environmental Management And Rehabilitation | Biochemistry and Cell Biology not elsewhere classified | Microbiology not elsewhere classified | Animal Physiology - Cell | Cell Development (Incl. Cell Division And Apoptosis) | Analytical Chemistry Not Elsewhere Classified | Computer Hardware Not Elsewhere Classified | Genetic Technologies: Transformation, Site-Directed Mutagenesis, Etc. | Genetically Modified Field Crops and Pasture
ANZSRC Socio-Economic Objective (SEO)
Field crops | Grain legumes | Wheat | Biological sciences | Expanding Knowledge in the Agricultural and Veterinary Sciences | Expanding Knowledge in the Biological Sciences | Wheat | Wine Grapes | Grapes | Barley | Land and water management | Beverages (e.g. alcohol, wines, soft drinks, excl. fruit juices) | Rice | Plant Production and Plant Primary Products not elsewhere classified | Primary products from plants | Horticultural crops | Chemical sciences | Environmentally Sustainable Plant Production not elsewhere classified | Maize | Rehabilitation of degraded mining lands | Beverages (excl. Fruit Juices) | Higher education | Expanding Knowledge in the Medical and Health Sciences | Industrial Crops not elsewhere classified | Primary plant products not elsewhere classified |
Related Links
Publications
Plasma membrane of Beta vulgaris storage root shows high water channel activity regulated by cytoplasmic pH and a dual range of calcium concentrations
Publisher: Oxford University Press (OUP)
Date: 05-01-2006
DOI: 10.1093/JXB/ERJ046
Abstract: Plasma membrane vesicles isolated by two-phase partitioning from the storage root of Beta vulgaris show atypically high water permeability that is equivalent only to those reported for active aquaporins in tonoplast or animal red cells (Pf=542 microm s(-1)). The values were determined from the shrinking kinetics measured by stopped-flow light scattering. This high Pf was only partially inhibited by mercury (HgCl2) but showed low activation energy (Ea) consistent with water permeation through water channels. To study short-term regulation of water transport that could be the result of channel gating, the effects of pH, alent cations, and protection against dephosphorylation were tested. The high Pf observed at pH 8.3 was dramatically reduced by medium acidification. Moreover, intra-vesicular acidification (corresponding to the cytoplasmic face of the membrane) shut down the aquaporins. De-phosphorylation was discounted as a regulatory mechanism in this preparation. On the other hand, among alent cations, only calcium showed a clear effect on aquaporin activity, with two distinct ranges of sensitivity to free Ca2+ concentration (pCa 8 and pCa 4). Since the normal cytoplasmic free Ca2+ sits between these ranges it allows for the possibility of changes in Ca2+ to finely up- or down-regulate water channel activity. The calcium effect is predominantly on the cytoplasmic face, and inhibition corresponds to an increase in the activation energy for water transport. In conclusion, these findings establish both cytoplasmic pH and Ca2+ as important regulatory factors involved in aquaporin gating.
Water Flow in the Roots of Crop Species: The Influence of Root Structure, Aquaporin Activity, and Waterlogging
Publisher: Elsevier
Date: 2007
Pump and K+ inward rectifiers in the plasmalemma of wheat root protoplasts
Publisher: Springer Science and Business Media LLC
Date: 04-1994
DOI: 10.1007/BF00232429
Role of TaALMT1 malate‐GABA transporter in alkaline pH tolerance of wheat
Publisher: Wiley
Date: 20-08-2020
DOI: 10.1111/PCE.13845
The role of ion channels in plant nutrition and prospects for their genetic manipulation
Publisher: Springer Science and Business Media LLC
Date: 10-1992
DOI: 10.1007/BF00012006
Tolerance of salinized floodplain condition in a naturally occurring Eucalyptus hybrid related to lowered plant water potential
Publisher: Oxford University Press (OUP)
Date: 08-2000
DOI: 10.1093/TREEPHYS/20.14.953
Abstract: Rising saline groundwater and reduced flooding frequency are causing dieback of Eucalyptus largiflorens F. Muell. along the Murray River in Australia. A green-leaved variant of E. largiflorens, which is probably a hybrid with a local mallee species (E. gracilis F. Muell.), tolerates saline conditions better than the more common grey-leaved variant. The green variant exhibited more negative water potentials than the grey variant, and comparison with soil water potential profiles indicated that the green variant extracted water from slightly higher up the soil profile where the salt content was lower but the soil was drier. However, the stable isotopes of water (2H and 18O) in the xylem did not differ significantly between paired green and grey trees, suggesting that both variants used the same water source. The green variant may be able to extract water for a longer period from a given point in the soil profile and tolerate a higher salt concentration around its roots than the grey variant. Predawn leaf water potentials of both variants decreased with increasing salinity of groundwater and decreasing depth to the groundwater, probably because the roots were being progressively confined to soil with lower matric potential as groundwater discharge through transpiration progressively salinized soil up the profile. The green variant had a lower assimilation rate and stomatal conductance than the grey variant, although the differences were not statistically significant during most of the year. Discrimination of 13C indicated that the green variant had a higher leaf internal CO2 concentration than the grey variant, indicative of a greater biochemical limitation on photosynthesis, perhaps resulting from the effects of operating at lower water potentials. The green variant had significantly lower stem hydraulic conductivity than the grey variant, probably because of its smaller xylem vessel diameter and higher degree of embolism. The more conservative water use of the green variant and its ability to operate at lower water potential than the grey variant appear to underlie its ability to tolerate conditions of reduced useable water above the saline groundwater. This advantage appears to outweigh the costs of increased xylem embolism and reduced assimilation.
Abscisic Acid Down-Regulates Hydraulic Conductance of Grapevine Leaves in Isohydric Genotypes Only
Publisher: Oxford University Press (OUP)
Date: 12-09-2017
DOI: 10.1104/PP.17.00698
Water relations and gas exchange of the root hemiparasite Santalum acuminatum (quandong)
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/BT00080
Abstract: The water relations and leaf gas-exchange characteristics of the root hemiparasite quandong (Santalum acuminatum (R.Br.) A.DC) and its neighbouring plants were examined at three field sites in central Southern Australia. This paper examines the role of water potential and osmotic gradients in facilitating the movement of water from host plants to quandong. Quandong exhibited a significantly more negative water potential than the neighbouring plant species at both field sites during summer and winter. A significant proportion of the osmotic potential was accounted for by mannitol, Na + , K + and Cl - . A water potential difference of 1.7 MPa was maintained between quandong and its putative host over a measurement period of 24 h. Xylem sap and leaves of quandong contained considerable concentration (0.1–0.4 mol (kg tissue water) –1 ) of mannitol. Stomatal conductance and assimilation of quandong were lower than those of the neighbouring plants at both Middleback and Aldinga during both summer and winter measurements. Measurements of transpiration for quandong differed between the two sites. The lower transpirational water loss resulted in quandong at Middleback having an instantaneous water-use efficiency higher (0.13–2.2 µmol (CO 2 ) mmol –1 (H 2 O)) than the neighbouring plants. Daily sap flow and calculated hydraulic conductivity were not significantly different between quandong and putative host plant.
Ammonia and amino acid transport across symbiotic membranes in nitrogen-fixing legume nodules
Publisher: Springer Science and Business Media LLC
Date: 2001
DOI: 10.1007/PL00000778
Evolution of chloroplast retrograde signaling facilitates green plant adaptation to land
Publisher: Proceedings of the National Academy of Sciences
Date: 25-02-2019
Abstract: Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades linking chloroplast function to stomatal regulation. We show that key elements of the chloroplast retrograde signaling process, the nucleotide phosphatase (SAL1) and 3′-phosphoadenosine-5′-phosphate (PAP) metabolism, evolved in streptophyte algae—the algal ancestors of land plants. We discover an early evolution of SAL1-PAP chloroplast retrograde signaling in stomatal regulation based on conserved gene and protein structure, function, and enzyme activity and transit peptides of SAL1s in species including flowering plants, the fern Ceratopteris richardii , and the moss Physcomitrella patens . Moreover, we demonstrate that PAP regulates stomatal closure via secondary messengers and ion transport in guard cells of these erse lineages. The origin of stomata facilitated gas exchange in the earliest land plants. Our findings suggest that the conquest of land by plants was enabled by rapid response to drought stress through the deployment of an ancestral SAL1-PAP signaling pathway, intersecting with the core abscisic acid signaling in stomatal guard cells.
Identification and functional characterisation of aquaporins in the grapevine, Vitis vinifera
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/FP09117
Abstract: Plant aquaporins belong to a large superfamily of conserved proteins called the major intrinsic proteins (MIPs). There is limited information about the ersity of MIPs in grapevine, and their water transport capacity. The aim of the present study was to identify MIPs from grapevine and functionally characterise water transport of a subset of MIPs. Candidate genes were identified, by screening a Vitis vinifera L. (cv. Cabernet Sauvignon) cDNA library with gene specific probes, for aquaporin cDNAs encoding members of the plasma membrane intrinsic protein (PIP) and tonoplast intrinsic protein (TIP) subfamilies. The screen resulted in the identification of 11 full-length and two partial length aquaporin cDNAs. VvTIP2 isoforms had different 3′ UTRs, immediately upstream of the poly(A) tail, suggesting the presence of multiple cleavage sites for polyadenylation. Using published genome sequences of grapevine, we conducted a phylogenetic analysis of the MIPs with previously characterised MIPs from Arabidopsis. We identified 23 full-length MIP genes from the V. vinifera genome sequence of a near homozygous line (PN40024) that cluster into the four main subfamilies (and subgroups within) identified in other species. However, based on the identification of PIP2 genes in Cabernet Sauvignon that were not present in the PN40024 genome, there are likely to be more than 23 MIP genes in other heterozygous grapevine cultivars. Water transport capacity was determined for several PIPs and TIPs, by expression in Xenopus oocytes. Only VvPIP2 and VvTIP proteins function as water channels with the exception of VvPIP2 . VvPIP2 differs from the water conducting VvPIP2 by the substitution of two highly conserved amino acids in Loop B (G97S, G100W), which was shown by homology modelling to likely form a hydrophobic block of the water pore.
Composition and synthesis of raphide crystals and druse crystals in berries of Vitis vinifera L. cv. Cabernet Sauvignon: Ascorbic acid as precursor for both oxalic and tartaric acids as revealed by radiolabelling studies
Publisher: Hindawi Limited
Date: 07-2004
Calcium-dependent K current in plasma membranes of dermal cells of developing bean cotyledons
Publisher: Wiley
Date: 02-2004
The devil in the detail of secretions
Publisher: Wiley
Date: 06-05-2013
DOI: 10.1111/PCE.12110
Night-time responses to water supply in grapevines (Vitis vinifera L.) under deficit irrigation and partial root-zone drying
Publisher: Elsevier BV
Date: 05-2014
Tree water sources over shallow, saline groundwater in the lower River Murray, south-eastern Australia: Implications for groundwater recharge mechanisms
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/BT05019
Abstract: The decline of riparian vegetation in the lower River Murray, south-eastern Australia, is associated with a reduction in flooding frequency, extent and duration, and increased salt accumulation. The plant water sources of healthy Eucalyptus largiflorens trees growing over highly saline ( dS m–1) groundwater were investigated during summer when water deficit is greatest. The study found low-salinity soil water overlying highly saline groundwater at most sites. This deep soil water, rather than the saline groundwater, was identified as the plant water source at most sites. Stable isotopes of water and water potential measurements were used to infer how the deep soil water was recharged. The low-salinity, deep soil water was recharged in the following two ways: (1) vertically through the soil profile or via preferential flow paths by rainfall or flood waters or (2) horizontally by bank recharge from surface water on top of the saline groundwater. Vertical infiltration of rainfall and floodwaters through cracking clays was important for trees growing in small depressions, whereas infiltration of rainfall through sandy soils was important for trees growing at the break of slope. Bank recharge was important for trees growing within ∼50 m of permanent and ephemeral water bodies. The study has provided a better understanding of the spatial patterns of recharge at a scale relevant to riparian vegetation. This understanding is important for the management of floodplain vegetation growing in a saline, semi-arid environment.
Expression of the wheat multipathogen resistance hexose transporter Lr67res is associated with anion fluxes
Publisher: Oxford University Press (OUP)
Date: 21-02-2023
Abstract: Many disease resistance genes in wheat (Triticum aestivum L.) confer strong resistance to specific pathogen races or strains, and only a small number of genes confer multipathogen resistance. The Leaf rust resistance 67 (Lr67) gene fits into the latter category as it confers partial resistance to multiple biotrophic fungal pathogens in wheat and encodes a Sugar Transport Protein 13 (STP13) family hexose-proton symporter variant. Two mutations (G144R, V387L) in the resistant variant, Lr67res, differentiate it from the susceptible Lr67sus variant. The molecular function of the Lr67res protein is not understood, and this study aimed to broaden our knowledge on this topic. Biophysical analysis of the wheat Lr67sus and Lr67res protein variants was performed using Xenopus laevis oocytes as a heterologous expression system. Oocytes injected with Lr67sus displayed properties typically associated with proton-coupled sugar transport proteins—glucose-dependent inward currents, a Km of 110 ± 10 µM glucose, and a substrate selectivity permitting the transport of pentoses and hexoses. By contrast, Lr67res induced much larger sugar-independent inward currents in oocytes, implicating an alternative function. Since Lr67res is a mutated hexose-proton symporter, the possibility of protons underlying these currents was investigated but rejected. Instead, currents in Lr67res oocytes appeared to be dominated by anions. This conclusion was supported by electrophysiology and 36Cl− uptake studies and the similarities with oocytes expressing the known chloride channel from Torpedo marmorata, TmClC-0. This study provides insights into the function of an important disease resistance gene in wheat, which can be used to determine how this gene variant underpins disease resistance in planta.
Hypoxia in the grape berry linked to mesocarp cell death: the role of seed respiration and lenticels on the berry pedicel
Publisher: Cold Spring Harbor Laboratory
Date: 27-10-2017
DOI: 10.1101/209890
Abstract: Mesocarp cell death (CD) during ripening is common in berries of seeded Vitis vinifera L wine cultivars. We examined if hypoxia within berries is linked to CD. Internal oxygen concentration ([O 2 ]) across the mesocarp was measured in berries from Chardonnay and Shiraz, both seeded, and Ruby Seedless, using an oxygen micro-sensor. Steep [O 2 ] gradients were observed across the skin and [O 2 ] decreased toward the middle of the mesocarp. As ripening progressed the minimum [O 2 ] approached zero in the seeded cultivars and correlated to CD. Seed respiration was a large proportion of total berry respiration early in ripening but did not account for O 2 deficiency late in ripening. [O 2 ] increased towards the central axis corresponding to the presence of air spaces visualised using x-ray microCT. These connect to lenticels on the pedicel that were critical for berry O 2 uptake as a function of temperature, and when blocked caused anoxia in the berry, ethanol accumulation and CD. Lenticel area on Chardonnay pedicels was higher than that for Shiraz probably accounting for the lower sensitivity of Chardonnay berry CD to high temperatures. The implications of hypoxia in grape berries are discussed in terms of its role in ripening and berry water relations. Grape berry internal oxygen concentration is dependent upon lenticels on the pedicel and cultivar differences in lenticels may account for temperature sensitivity of cell death in the mesocarp.
Chloroplast function and ion regulation in plants growing on saline soils: lessons from halophytes
Publisher: Oxford University Press (OUP)
Date: 02-05-2017
DOI: 10.1093/JXB/ERX142
Abstract: Salt stress impacts multiple aspects of plant metabolism and physiology. For instance it inhibits photosynthesis through stomatal limitation, causes excessive accumulation of sodium and chloride in chloroplasts, and disturbs chloroplast potassium homeostasis. Most research on salt stress has focused primarily on cytosolic ion homeostasis with few studies of how salt stress affects chloroplast ion homeostasis. This review asks the question whether membrane-transport processes and ionic relations are differentially regulated between glycophyte and halophyte chloroplasts and whether this contributes to the superior salt tolerance of halophytes. The available literature indicates that halophytes can overcome stomatal limitation by switching to CO2 concentrating mechanisms and increasing the number of chloroplasts per cell under saline conditions. Furthermore, salt entry into the chloroplast stroma may be critical for grana formation and photosystem II activity in halophytes but not in glycophytes. Salt also inhibits some stromal enzymes (e.g. fructose-1,6-bisphosphatase) to a lesser extent in halophyte species. Halophytes accumulate more chloride in chloroplasts than glycophytes and appear to use sodium in functional roles. We propose the molecular identities of candidate transporters that move sodium, chloride and potassium across chloroplast membranes and discuss how their operation may regulate photochemistry and photosystem I and II activity in chloroplasts.
Cytosolic GABA inhibits anion transport by wheat ALMT1.
Publisher: Wiley
Date: 03-11-2020
DOI: 10.1111/NPH.16238
Abstract: Anion transport by aluminium-activated malate transporter (ALMT) proteins is negatively regulated by gamma-aminobutyric acid (GABA), which increases in concentration during stress. Here, the interaction between GABA and wheat (Triticum aestivum, Ta) TaALMT1 heterologously-expressed in Xenopus laevis oocytes was investigated. GABA inhibited anion transport by TaALMT1 in membrane patches from the cytosolic, not extracellular membrane face, via a reduction in open probability (NP
Postveraison Leaf Removal Does Not Consistently Delay Ripening in Semillon and Shiraz in a Hot Australian Climate
Publisher: American Society for Enology and Viticulture
Date: 07-06-2019
Root growth of lupins is more sensitive to waterlogging than wheat
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/FP11148
Abstract: In south-west Australia, winter grown crops such as wheat and lupin often experience transient waterlogging during periods of high rainfall. Wheat is believed to be more tolerant to waterlogging than lupins, but until now no direct comparisons have been made. The effects of waterlogging on root growth and anatomy were compared in wheat (Triticum aestivum L.), narrow-leafed lupin (Lupinus angustifolius L.) and yellow lupin (Lupinus luteus L.) using 1 m deep root observation chambers. Seven days of waterlogging stopped root growth in all species, except some nodal root development in wheat. Roots of both lupin species died back progressively from the tips while waterlogged. After draining the chambers, wheat root growth resumed in the apical region at a faster rate than well-drained plants, so that total root length was similar in waterlogged and well-drained plants at the end of the experiment. Root growth in yellow lupin resumed in the basal region, but was insufficient to compensate for root death during waterlogging. Narrow-leafed lupin roots did not recover they continued to deteriorate. The survival and recovery of roots in response to waterlogging was related to anatomical features that influence internal oxygen deficiency and root hydraulic properties.
A channel-like transporter for NH4+ on the symbiotic interface of N2-fixing plants
Publisher: Springer Science and Business Media LLC
Date: 12-1995
DOI: 10.1038/378629A0
Linking Metabolism to Membrane Signaling: The GABA-Malate Connection.
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.TPLANTS.2015.11.011
Abstract: γ-Aminobutyric acid (GABA) concentration increases rapidly in tissues when plants encounter abiotic or biotic stress, and GABA manipulation affects growth. This, coupled to GABA's well-described role as a neurotransmitter in mammals, led to over a decade of speculation that GABA is a signal in plants. The discovery of GABA-regulated anion channels in plants provides compelling mechanistic proof that GABA is a legitimate plant-signaling molecule. Here we examine research avenues unlocked by this finding and propose that these plant 'GABA receptors' possess novel properties ideally suited to translating changes in metabolic status into physiological responses. Specifically, we suggest they have a role in signaling altered cycling of tricarboxylic acid (TCA) intermediates during stress via eliciting changes in electrical potential differences across membranes.
Nonselective cation channels. Multiple functions and commonalities
Publisher: Oxford University Press (OUP)
Date: 02-2002
DOI: 10.1104/PP.900021
Divalent Cations Regulate the Ion Conductance Properties of Diverse Classes of Aquaporins
Publisher: MDPI AG
Date: 03-11-2017
DOI: 10.3390/IJMS18112323
Aluminum-Activated Malate Transporters Can Facilitate GABA Transport
Publisher: Oxford University Press (OUP)
Date: 04-04-2018
DOI: 10.1105/TPC.17.00864
Aluminum activates an anion channel in the apical cells of wheat roots
Publisher: Proceedings of the National Academy of Sciences
Date: 10-06-1997
Abstract: We describe an anion channel in the plasmalemma of protoplasts isolated from wheat ( Triticum aestivum L.) roots that is activated by aluminum (Al 3+ ). In the whole-cell configuration, addition of 20–50 μM AlCl 3 to the external solution depolarized the membrane and activated an inward current that could remain active for more than 60 min. The activation by Al 3+ was rapid in 20% of protoplasts examined, whereas in another 30% a delay of more than 10 min occurred after Al 3+ was added. Once the current was activated, changing the external Cl − concentration shifted the membrane reversal potential with E Cl , showing that the channel is more selective for anions than cations (Ca 2+ , K + , tetraethylammonium + ). The channel could be activated by Al 3+ , but not by La 3+ , and was observed in protoplasts isolated from the root apex but not in protoplasts isolated from mature root tissue. The anion channel antagonist niflumate inhibited the current in whole cell measurements by 83% at 100 μM. Outside-out patch recordings revealed a multistate channel with single-channel conductances of between 27 and 66 pS.
Electrical impedance of Shiraz berries correlates with decreasing cell vitality during ripening
Publisher: Hindawi Limited
Date: 05-08-2015
DOI: 10.1111/AJGW.12157
Current-voltage curves of single CI- channels which coexist with two types of K+ channel in the tonoplast of Chara corallina
Publisher: Oxford University Press (OUP)
Date: 1989
DOI: 10.1093/JXB/40.1.105
Statistical modeling of nitrogen‐dependent modulation of root system architecture in Arabidopsis thaliana
Publisher: Wiley
Date: 02-11-2015
DOI: 10.1111/JIPB.12433
Abstract: Plant root development is strongly affected by nutrient availability. Despite the importance of structure and function of roots in nutrient acquisition, statistical modeling approaches to evaluate dynamic and temporal modulations of root system architecture in response to nutrient availability have remained as widely open and exploratory areas in root biology. In this study, we developed a statistical modeling approach to investigate modulations of root system architecture in response to nitrogen availability. Mathematical models were designed for quantitative assessment of root growth and root branching phenotypes and their dynamic relationships based on hierarchical configuration of primary and lateral roots formulating the fishbone-shaped root system architecture in Arabidopsis thaliana. Time-series datasets reporting dynamic changes in root developmental traits on different nitrate or ammonium concentrations were generated for statistical analyses. Regression analyses unraveled key parameters associated with: (i) inhibition of primary root growth under nitrogen limitation or on ammonium (ii) rapid progression of lateral root emergence in response to ammonium and (iii) inhibition of lateral root elongation in the presence of excess nitrate or ammonium. This study provides a statistical framework for interpreting dynamic modulation of root system architecture, supported by meta-analysis of datasets displaying morphological responses of roots to erse nitrogen supplies.
Water transport & aquaporins in grapevine
Publisher: Springer Netherlands
Date: 2009
Channel-mediated permeation of ammonia gas through the peribacteroid membrane of soybean nodules
Publisher: Wiley
Date: 14-01-2000
DOI: 10.1016/S0014-5793(99)01729-9
Abstract: Ammonia permeability of the peribacteroid membrane (PBM) from N(2)-fixing soybean nodules was measured (8x10(-5) m/s) using isolated PBM in a stopped-flow spectrofluorimeter. Ammonia (NH(3)) uptake into PBM vesicles was inhibited by up to 42% by HgCl(2) (EC(50)=2.9 microM, mercaptoethanol-reversible) and reduced by ATP pre-incubation. The activation energy of NH(3) uptake (52 kJ/mol) increased (118 kJ/mol) with HgCl(2). Water transport was also HgCl(2)-sensitive (EC(50)=52.6 microM), but increased by ATP pre-incubation. NH(3) and H(2)O may permeate via different pathways through Nodulin 26 or there is another protein on the PBM that is permeable to NH(3).
Energy costs of salinity tolerance in crop plants
Publisher: Wiley
Date: 29-11-2019
DOI: 10.1111/NPH.15555
Molybdate transport through the plant sulfate transporter SHST1
Publisher: Wiley
Date: 23-04-2008
DOI: 10.1016/J.FEBSLET.2008.03.045
Abstract: Molybdenum is an essential micronutrient required by plants. The mechanism of molybdenum uptake in plants is poorly understood, however, evidence has suggested that sulfate transporters may be involved. The sulfate transporter from Stylosanthes hamata, SHST1, restored growth of the sulfate transport yeast mutant, YSD1, on media containing low amounts of molybdate. Kinetic analysis using 99MoO4(2-) demonstrated that SHST1 enhanced the uptake of molybdate into yeast cells at nM concentrations. Uptake was not inhibited by sulfate, but sulfate transport via SHST1 was reduced with molybdate. These results are the first measurement of molybdate transport by a characterised plant sulfate transport protein.
Impact of deficit irrigation strategies in a saline environment on Shiraz yield, physiology, water use and tissue ion concentration
Publisher: Hindawi Limited
Date: 25-06-2015
DOI: 10.1111/AJGW.12151
Impact of grapevine exposure to smoke on vine physiology and the composition and sensory properties of wine
Publisher: Springer Science and Business Media LLC
Date: 15-02-2016
Enhancing crop yields through improvements in the efficiency of photosynthesis and respiration
Publisher: Wiley
Date: 17-11-2023
DOI: 10.1111/NPH.18545
Abstract: The rate with which crop yields per hectare increase each year is plateauing at the same time that human population growth and other factors increase food demand. Increasing yield potential () of crops is vital to address these challenges. In this review, we explore a component of that has yet to be optimised – that being improvements in the efficiency with which light energy is converted into biomass () via modifications to CO 2 fixed per unit quantum of light ( α ), efficiency of respiratory ATP production () and efficiency of ATP use (). For α , targets include changes in photoprotective machinery, ribulose bisphosphate carboxylase/oxygenase kinetics and photorespiratory pathways. There is also potential for to be increased via targeted changes to the expression of the alternative oxidase and mitochondrial uncoupling pathways. Similarly, there are possibilities to improve via changes to the ATP costs of phloem loading, nutrient uptake, futile cycles and/or protein/membrane turnover. Recently developed high‐throughput measurements of respiration can serve as a proxy for the cumulative energy cost of these processes. There are thus exciting opportunities to use our growing knowledge of factors influencing the efficiency of photosynthesis and respiration to create a step‐change in yield potential of globally important crops.
Chloride transport and compartmentation within main and lateral roots of two grapevine rootstocks differing in salt tolerance
Publisher: Springer Science and Business Media LLC
Date: 18-04-2013
Burning questions for a warming and changing world: 15 unknowns in plant abiotic stress
Publisher: Oxford University Press (OUP)
Date: 26-08-2022
Abstract: We present unresolved questions in plant abiotic stress biology as posed by 15 research groups with expertise spanning eco-physiology to cell and molecular biology. Common themes of these questions include the need to better understand how plants detect water availability, temperature, salinity, and rising carbon dioxide (CO2) levels how environmental signals interface with endogenous signaling and development (e.g. circadian clock and flowering time) and how this integrated signaling controls downstream responses (e.g. stomatal regulation, proline metabolism, and growth versus defense balance). The plasma membrane comes up frequently as a site of key signaling and transport events (e.g. mechanosensing and lipid-derived signaling, aquaporins). Adaptation to water extremes and rising CO2 affects hydraulic architecture and transpiration, as well as root and shoot growth and morphology, in ways not fully understood. Environmental adaptation involves tradeoffs that limit ecological distribution and crop resilience in the face of changing and increasingly unpredictable environments. Exploration of plant ersity within and among species can help us know which of these tradeoffs represent fundamental limits and which ones can be circumvented by bringing new trait combinations together. Better defining what constitutes beneficial stress resistance in different contexts and making connections between genes and phenotypes, and between laboratory and field observations, are overarching challenges.
A novel method based on combination of semi-in vitro and in vivo conditions in Agrobacterium rhizogenes-mediated hairy root transformation of Glycine species
Publisher: Springer Science and Business Media LLC
Date: 21-11-2013
Soybean SAT1 ( Symbiotic Ammonium Transporter 1 ) encodes a bHLH transcription factor involved in nodule growth and NH 4 + transport
Publisher: Proceedings of the National Academy of Sciences
Date: 19-03-2014
Abstract: The legume/rhizobia symbiosis involves a root-based exchange of bacterial fixed nitrogen for plant-derived photosynthetic carbon. The exchange takes place within the legume root nodule, which is a specialized root tissue that develops in response to plant and bacterial signal exchange. The bacteria reside within plant cells inside the nodule. In this study, we explore the activity of a membrane-bound soybean transcription factor, Glycine max basic–helix-loop–helix membrane 1, which is important for soybean nodule growth and is linked to the activity of a unique class of ammonium channels and to signaling cascades influencing a nodule circadian clock.
The contrasting influence of short-term hypoxia on the hydraulic properties of cells and roots of wheat and lupin
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/FP09172
Abstract: Little is known about water flow across intact root cells and roots in response to hypoxia. Responses may be rapid if regulated by aquaporin activity, but only if water crosses membranes. We measured the transport properties of roots and cortical cells of three important crop species in response to hypoxia (0.05 mol O2 m–3): wheat (Triticum aestivum L.), narrow-leafed lupin (Lupinus angustifolius L.) and yellow lupin (Lupinus luteus L.). Hypoxia influenced solute transport within minutes of exposure as indicated by increases in root pressure (Pr) and decreases in turgor pressure (Pc), but these effects were only significant in lupins. Re-aeration returned Pr to original levels in yellow lupin, but in narrow-leafed lupin, Pr declined to zero or lower values without recovery even when re-aerated. Hypoxia inhibited hydraulic conductivity of root cortical cells (Lpc) in all three species, but only inhibited hydraulic conductivity of roots (Lpr) in wheat, indicating different pathways for radial water flow across lupin and wheat roots. The inhibition of Lpr of wheat depended on the length of the root, and inhibition of Lpc in the endodermis could account for the changes in Lpr. During re-aeration, aquaporin activity increased in wheat roots causing an overshoot in Lpr. The results of this study demonstrate that the roots of these species not only vary in hydraulic properties but also vary in their sensitivity to the same external O2 concentration.
A putative role for TIP and PIP aquaporins in dynamics of leaf hydraulic and stomatal conductances in grapevine under water stress and re‐watering
Publisher: Wiley
Date: 11-2012
DOI: 10.1111/PCE.12019
Abstract: We examined the role of aquaporins (AQPs) in regulating leaf hydraulic conductance (Kleaf ) in Vitis vinifera L. (cv Chardonnay) by studying effects of AQP inhibitors, and AQP gene expression during water stress (WS) and recovery (REC). Kleaf was measured after 3 h of petiole perfusion with different solutions and to introduce inhibitors. The addition of 0.1 mm HgCl2 to 15 mm KCl reduced Kleaf compared with perfusion in 15 mM KNO3 or KCl, and these solutions were used for leaves from control, WS and REC plants. Perfusion for 3 h did not significantly alter stomatal conductance (gs ) though expression of VvTIP1 was increased. WS decreased Kleaf by about 30% and was correlated with gs . The expression of VvTIP2 and VvPIP2 correlated with Kleaf , and VvTIP2 was highly correlated with gs . There was no association between the expression of particular AQPs during WS and REC and inhibition of Kleaf by HgCl2 however, HgCl2 treatment itself increased expression of VvPIP2 and decreased expression of VvPIP2 . Inhibition by HgCl2 of Kleaf only at early stages of WS and then after REC suggested that apoplasmic pathways become more important during WS. This was confirmed using fluorescent dyes confined to apoplasm or preferentially accumulated in symplasm.
The dual benefit of arbuscular mycorrhizal fungi under soil zinc deficiency and toxicity
Publisher: Springer Science and Business Media LLC
Date: 12-09-2017
Cell death in grape berries: Varietal differences linked to xylem pressure and berry weight loss
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/FP07278
Abstract: Some varieties of Vitis vinifera L. can undergo berry weight loss during later stages of ripening. This defines a third phase of development in addition to berry formation and berry expansion. Berry weight loss is due to net water loss, but the component water flows through different pathways have remained obscure. Because of the very negative osmotic potential of the cell sap, the maintenance of semipermeable membranes in the berry is required for the berry to counter xylem and apoplast tensions that may be transferred from the vine. The transfer of tension is determined by the hydraulic connection through the xylem from the berry to the vine, which changes during development. Here we assess the membrane integrity of three varieties of V. vinifera berries (cvv. Shiraz, Chardonnay and Thompson seedless) throughout development using the vitality stains, fluorescein diacetate and propidium iodide, on fresh longitudinal sections of whole berries. We also measured the xylem pressure using a pressure probe connected to the pedicel of detached berries. The wine grapes, Chardonnay and Shiraz, maintained fully vital cells after veraison and during berry expansion, but began to show cell death in the mesocarp and endocarp at or near the time that the berries attain maximum weight. This corresponded to a change in rate of accumulation of solutes in the berry and the beginning of weight loss in Shiraz, but not in Chardonnay. Continuous decline in mesocarp and endocarp cell vitality occurred for both varieties until normal harvest dates. Shiraz grapes classified as high quality and sourced from a different vineyard also showed the same death response at the same time after anthesis, but they displayed a more consistent pattern of pericarp cell death. The table grape, Thompson seedless, showed near to 100% vitality for all cells throughout development and well past normal harvest date, except for berries with noticeable berry collapse that were treated with giberellic acid. The high cell vitality in Thompson seedless berries corresponded to negative xylem pressures that contrasted to the slightly positive pressures for Shiraz and Chardonnay. We hypothesise that two variety dependent strategies exist for grapevine berries late in development: (1) programmed cell death in the pericarp and loss of osmotically competent membranes that requires concomitant reduction in the hydraulic conductance via the xylem to the vine (2) continued cell vitality and osmotically competent membranes that can allow high hydraulic conductance to the vine.
The effects of sustained deficit irrigation and re-watering on root production and turnover in warm climate viticulture
Publisher: International Society for Horticultural Science (ISHS)
Date: 07-2016
Wheat grain yield on saline soils is improved by an ancestral Na+ transporter gene
Publisher: Springer Science and Business Media LLC
Date: 11-03-2012
DOI: 10.1038/NBT.2120
Abstract: The ability of wheat to maintain a low sodium concentration ([Na(+)]) in leaves correlates with improved growth under saline conditions. This trait, termed Na(+) exclusion, contributes to the greater salt tolerance of bread wheat relative to durum wheat. To improve the salt tolerance of durum wheat, we explored natural ersity in shoot Na(+) exclusion within ancestral wheat germplasm. Previously, we showed that crossing of Nax2, a gene locus in the wheat relative Triticum monococcum into a commercial durum wheat (Triticum turgidum ssp. durum var. Tamaroi) reduced its leaf [Na(+)] (ref. 5). Here we show that a gene in the Nax2 locus, TmHKT1 -A, encodes a Na(+)-selective transporter located on the plasma membrane of root cells surrounding xylem vessels, which is therefore ideally localized to withdraw Na(+) from the xylem and reduce transport of Na(+) to leaves. Field trials on saline soils demonstrate that the presence of TmHKT1 -A significantly reduces leaf [Na(+)] and increases durum wheat grain yield by 25% compared to near-isogenic lines without the Nax2 locus.
A channel that allows inwardly directed fluxes of anions in protoplasts derived from wheat roots
Publisher: Springer Science and Business Media LLC
Date: 1994
DOI: 10.1007/BF00198563
The Genetic Envelope of Winegrape Vines: Potential for Adaptation to Future Climate Challenges
Publisher: Wiley
Date: 18-08-2011
Characterisation of internal oxygen concentration of strawberry (
Publisher: CSIRO Publishing
Date: 16-12-2022
DOI: 10.1071/FP21259
Abstract: Gas exchange mechanisms play crucial roles in maintaining fruit post-harvest quality in perishable fruit such as strawberry (Fragaria × ananassa Duch.) and blueberry (Vaccinium corymbosum L.). The internal oxygen concentration ([O2]) of strawberry and blueberry were measured using Clark-type oxygen sensing electrodes. The volume of intercellular voids in strawberry was obtained by micro-computed tomography (micro-CT). In both berries, internal [O2] was consistent and relatively high across measured tissues. The overall [O2] was well above the Michaelis constant (Km) for cytochrome c oxidase in both fruit and different from previously examined grape (Vitis vinifera L.) berry mesocarp with near zero minimum [O2]. In strawberry and blueberry, cell vitality was also maintained at full maturity in the mesocarp. Higher storage temperature (i.e. 20 vs 4°C) reduced internal [O2] of strawberry. Pedicel detachment in blueberry was associated with greater fruit dehydration and lower internal [O2] after short-term storage of 12 h. The results suggest that the intercellular voids of the fruit’s mesocarp provide an efficient gas exchange route for maintaining high fruit internal [O2] post-harvest.
Cell-specific vacuolar calcium storage mediated by CAX1 regulates apoplastic calcium concentration, gas exchange, and plant productivity in Arabidopsis
Publisher: Oxford University Press (OUP)
Date: 2011
Abstract: The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from Arabidopsis thaliana leaf cells differing in calcium concentration ([Ca], epidermis & mM versus mesophyll & mM) were compared using a microarray screen and single-cell quantitative PCR. Three tonoplast-localized Ca2+ transporters, CAX1 (Ca2+/H+-antiporter), ACA4, and ACA11 (Ca2+-ATPases), were identified as preferentially expressed in Ca-rich mesophyll. Analysis of respective loss-of-function mutants demonstrated that only a mutant that lacked expression of both CAX1 and CAX3, a gene ectopically expressed in leaves upon knockout of CAX1, had reduced mesophyll [Ca]. Reduced capacity for mesophyll Ca accumulation resulted in reduced cell wall extensibility, stomatal aperture, transpiration, CO2 assimilation, and leaf growth rate increased transcript abundance of other Ca2+ transporter genes altered expression of cell wall–modifying proteins, including members of the pectinmethylesterase, expansin, cellulose synthase, and polygalacturonase families and higher pectin concentrations and thicker cell walls. We demonstrate that these phenotypes result from altered apoplastic free [Ca2+], which is threefold greater in cax1/cax3 than in wild-type plants. We establish CAX1 as a key regulator of apoplastic [Ca2+] through compartmentation into mesophyll vacuoles, a mechanism essential for optimal plant function and productivity.
Grapevine and Arabidopsis cation-chloride cotransporters localise to the Golgi and trans-Golgi network and indirectly influence long-distance ion homeostasis and plant salt tolerance
Publisher: Oxford University Press (OUP)
Date: 16-09-2015
DOI: 10.1104/PP.15.00499
Exogenous application of abscisic acid to root systems of grapevines with or without salinity influences water relations and ion allocation
Publisher: Hindawi Limited
Date: 24-01-2017
DOI: 10.1111/AJGW.12264
TRANSPIRATION RESPONSES TO POTENTIAL VOLATILE SIGNALS AND HYDRAULIC FAILURE IN SINGLE LEAVES OF VITIS VINIFERA (CV. SHIRAZ) AND ARABIDOPSIS THALIANA (COL 0) UTILISING SENSITIVE LIQUID FLOW AND SIMULTANEOUS GAS EXCHANGE.
Publisher: Authorea, Inc.
Date: 23-01-2023
DOI: 10.22541/AU.167449690.06357698/V1
Abstract: Volatile organic compounds (VOCs) may communicate stress between plants. However little appears to be documented on how such VOCs affect transpiration. Changes in transpiration in response to some VOCs was examined by measurement of flow ( Q ) at high resolution into detached leaves of Vitis vinifera (cv. Shiraz) and Arabidopsis (Col 0). Sensors recorded arrival and decay of volatiles at the leaf lamina. Moderate xylem tensions were developed in V. vinifera leaves by incorporating a hydraulic resistance in the flow pathway. Simultaneous recording of leaf gas exchange (Assimilation, A , and Transpiration, E ) for both V. vinifera and Arabidopsis revealed that for Arabidopsis Q was stochastically restricted by the gas exchange cuvette but not E in the short term. Depending on the applied supply pressure cavitation could be controlled in V. vinifera evident from reduced Q , and leaf wilting. Stomatal closure occurred upon cavitation after a transitory increase in E and A, and after wilting began and was reversed by re-pressurization. VOCs were emitted from leaves corresponding to changes in flow rate, and light to dark transitions but not to cavitation. Volatile methanol but not ethanol or methyl salicylate induced a localised dose-dependent reversible stomatal closure in both V. vinifera and Arabidopsis.
Characterization of water channels in wheat root membrane vesicles
Publisher: Oxford University Press (OUP)
Date: 10-1997
DOI: 10.1104/PP.115.2.561
Abstract: The functional significance of water channels in wheat (Triticum aestivum L.) root membranes was assessed using light scattering to measure vesicle shrinking in response to osmotic gradients rapidly imposed in a stopped flow apparatus. Vesicles were obtained from both a plasma membrane fraction and a plasma membrane-depleted endomembrane fraction including tonoplast vesicles. Osmotic water permeability (Pos) in the endomembrane fraction was high (Pos= 86.0 [mu]m s-1) with a low activation energy (EA= 23.32 kJ mol-1 [plus or minus] 3.88 SE), and was inhibited by mercurials (K1= 40 [mu]M HgCl2, where K1 is the inhibition constant for half-maximal inhibition), suggesting participation of water channels. A high ratio of osmotic to diffusional permeability (Pd) (using D2O as a tracer, Pos/Pd = 7 [plus or minus] 0.5 SE) also supported this view. For the endomembrane fraction there was a marked decrease in Pos with increasing osmotic gradient that was not observed in the plasma membrane fraction. Osmotic water permeability in the plasma membrane fraction was lower (Pos= 12.5 [mu]m s-1) with a high activation energy (EA= 48.07 kJ mol-1 [plus or minus] 3.63 SE) and no mercury inhibition. Nevertheless, Pos/Pd was found to be substantially higher than one (Pos= 3 [plus or minus] 0.2 SE), indicating that water channels mediated water flow in this fraction, too. Possible distortion of the Pos/Pd value by unstirred layer effects was shown to be unlikely.
Roles of Aquaporins in Setaria viridis Stem Development and Sugar Storage
Publisher: Frontiers Media SA
Date: 12-2016
Direct effects of Ca2+-channel blockers on plasma membrane cation channels of Amaranthus tricolor protoplasts
Publisher: Oxford University Press (OUP)
Date: 1992
Fruit Calcium: Transport and Physiology
Publisher: Frontiers Media SA
Date: 29-04-2016
Root apoplastic transport and water relations cannot account for differences in Cl− transport and Cl−/NO3 − interactions of two grapevine rootstocks differing in salt tolerance
Publisher: Springer Science and Business Media LLC
Date: 03-12-2013
Inward membrane current in Chara inflata: II. Effects of pH, Cl--channel blockers and NH4 +, and significance for the hyperpolarized state
Publisher: Springer Science and Business Media LLC
Date: 06-1986
DOI: 10.1007/BF01869711
Inward membrane current in Chara inflata: I. A voltage- and time-dependent Cl- component
Publisher: Springer Science and Business Media LLC
Date: 06-1986
DOI: 10.1007/BF01869710
Roles of Morphology, Anatomy, and Aquaporins in Determining Contrasting Hydraulic Behavior of Roots
Publisher: Oxford University Press (OUP)
Date: 25-03-2009
Abstract: The contrasting hydraulic properties of wheat (Triticum aestivum), narrow-leafed lupin (Lupinus angustifolius), and yellow lupin (Lupinus luteus) roots were identified by integrating measurements of water flow across different structural levels of organization with anatomy and modeling. Anatomy played a major role in root hydraulics, influencing axial conductance (L ax) and the distribution of water uptake along the root, with a more localized role for aquaporins (AQPs). Lupin roots had greater L ax than wheat roots, due to greater xylem development. L ax and root hydraulic conductance (L r) were related to each other, such that both variables increased with distance from the root tip in lupin roots. L ax and L r were constant with distance from the tip in wheat roots. Despite these contrasting behaviors, the hydraulic conductivity of root cells (Lp c) was similar for all species and increased from the root surface toward the endodermis. Lp c was largely controlled by AQPs, as demonstrated by dramatic reductions in Lp c by the AQP blocker mercury. Modeling the root as a series of concentric, cylindrical membranes, and the inhibition of AQP activity at the root level, indicated that water flow in lupin roots occurred primarily through the apoplast, without crossing membranes and without the involvement of AQPs. In contrast, water flow across wheat roots crossed mercury-sensitive AQPs in the endodermis, which significantly influenced L r. This study demonstrates the importance of examining root morphology and anatomy in assessing the role of AQPs in root hydraulics.
Comparison of isohydric and anisohydric Vitis vinifera L. cultivars reveals a fine balance between hydraulic resistances, driving forces and transpiration in ripening berries
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/FP16010
Abstract: The degree to which isohydric or anisohydric behaviour extends to the water balance of developing fruits has not previously been explored. Here, we examine the water relations and hydraulic behaviour of Vitis vinifera L. berries during development from two contrasting cultivars that display isohydric (cv. Grenache) or anisohydric (cv. Shiraz) behaviour. Hydraulic resistance normalised to the berry surface area of Grenache clusters was significantly lower and more constant during development, whereas that of Shiraz increased. Lower rachis hydraulic resistance in Grenache compared with Shiraz was inversely related to xylem vessel diameter. Berry transpiration and xylem water uptake measured on detached berries decreased alike during development. From veraison, detached berries of both cultivars showed a transition to a net imbalance between xylem water uptake and transpiration, with Shiraz showing a larger imbalance and berry dehydration towards the end of ripening. In planta, this imbalance must be counterbalanced by a larger phloem water influx in post-veraison berries. Concurrently, the calculated pressure gradients for xylem water uptake showed a decline, which broadly agreed with the measured values. Higher suction for xylem water uptake in pre-veraison berries was mainly generated by transpiration. We conclude that isohydric or anisohydric behaviour is reflected in the contrasting behaviour of fruit hydraulics and that a change from xylem water uptake to phloem import is correlated with the loss of the propensity to generate negative apoplastic pressure in the berry.
Proton‐coupled high‐affinity phosphate transport revealed from heterologous characterization in Xenopus of barley‐root plasma membrane transporter, HvPHT1;1
Publisher: Wiley
Date: 11-02-2011
DOI: 10.1111/J.1365-3040.2010.02272.X
Abstract: High-affinity phosphate transporters mediate uptake of inorganic phosphate (P(i) ) from soil solution under low P(i) conditions. The electrophysiological properties of any plant high-affinity P(i) transporter have not been described yet. Here, we report the detailed characterization of electrophysiological properties of the barley P(i) transporter, HvPHT1 in Xenopus laevis oocytes. A very low K(m) value (1.9 µm) for phosphate transport was observed in HvPHT1 , which falls within the concentration range observed for barley roots. Inward currents at negative membrane potentials were identified as nH+ :P(i)⁻ (n > 1) co-transport based on simultaneous P(i) radiotracer uptake, oocyte voltage cl ing and pH dependence. HvPHT1 showed preferential selectivity for P(i) and arsenate, but no transport of the other oxyanions SO₄²⁻ and NO₃⁻. In addition, HvPHT1 locates to the plasma membrane when expressed in onion (Allium cepa L.) epidermal cells, and is highly expressed in root segments with dense hairs. The electrophysiological properties, plasma membrane localization and cell-specific expression pattern of HvPHT1 support its role in the uptake of P(i) under low P(i) conditions.
Application of shade treatments during Shiraz berry ripening to reduce the impact of high temperature
Publisher: Hindawi Limited
Date: 09-09-2016
DOI: 10.1111/AJGW.12248
The emerging importance of the SPX domain‐containing proteins in phosphate homeostasis
Publisher: Wiley
Date: 05-01-2012
DOI: 10.1111/J.1469-8137.2011.04002.X
Abstract: Plant growth and development are strongly influenced by the availability of nutrients in the soil solution. Among them, phosphorus (P) is one of the most essential and most limiting macro‐elements for plants. In the environment, plants are often confronted with P starvation as a result of extremely low concentrations of soluble inorganic phosphate (Pi) in the soil. To cope with these conditions, plants have developed a wide spectrum of mechanisms aimed at increasing P use efficiency. At the molecular level, recent studies have shown that several proteins carrying the SPX domain are essential for maintaining Pi homeostasis in plants. The SPX domain is found in numerous eukaryotic proteins, including several proteins from the yeast PHO regulon, involved in maintaining Pi homeostasis. In plants, proteins harboring the SPX domain are classified into four families based on the presence of additional domains in their structure, namely the SPX, SPX‐EXS, SPX‐MFS and SPX‐RING families. In this review, we highlight the recent findings regarding the key roles of the proteins containing the SPX domain in phosphate signaling, as well as providing further research directions in order to improve our knowledge on P nutrition in plants, thus enabling the generation of plants with better P use efficiency.
An algal PIP-like aquaporin facilitates water transport and ionic conductance
Publisher: Elsevier BV
Date: 10-2021
Guard cell pressure/aperture characteristics measured with the pressure probe
Publisher: Wiley
Date: 07-1995
The function of the Medicago truncatula ZIP transporter MtZIP14 is linked to arbuscular mycorrhizal fungal colonization
Publisher: Wiley
Date: 29-01-2023
DOI: 10.1111/PCE.14545
Abstract: Soil micronutrient availability, including zinc (Zn), is a limiting factor for crop yield. Arbuscular mycorrhizal (AM) fungi can improve host plant growth and nutrition through the mycorrhizal pathway of nutrient uptake. Although the physiology of Zn uptake through the mycorrhizal pathway is well established, the identity of the related molecular components are unknown. Here, RNA‐seq analysis was used to identify genes differentially‐regulated by AM colonization and soil Zn concentration in roots of Medicago truncatula . The putative Zn transporter gene MtZIP14 was markedly up‐regulated in M. truncatula roots when colonized by Rhizophagus irregularis . MtZIP14 restored yeast growth under low Zn availability. Loss‐of‐function mutant plants ( mtzip14 ) had reduced shoot biomass compared to the wild‐type when colonized by AM fungi and grown under low and sufficient soil Zn concentration at high soil Zn concentration, there were no genotypic differences in shoot biomass. The vesicular and arbuscular colonization of roots was lower in the mtzip14 plants regardless of soil Zn concentration. We propose that MtZIP14 is linked to AM colonization in M. truncatula plants, with the possibility that MtZIP14 function with AM colonization is linked to plant Zn nutrition.
Phosphorylation influences water and ion channel function of
AtPIP2;1
Publisher: Wiley
Date: 17-08-2020
DOI: 10.1111/PCE.13851
The VvBAP1 gene is identified as a potential inhibitor of cell death in grape berries
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/FP18272
Abstract: Cell death (CD) in Vitis vinifera L grape berries, exemplified in Shiraz, occurs late in ripening influencing yield, berry and wine quality. Here we isolated and functionally characterised a BON1-associated gene, VvBAP1 from Shiraz berries, encoding a small protein with a C2 domain. VvBAP1 transcript increased during fruit development from veraison to harvest, and was significantly inhibited by drought stress 92 days after flowering when CD normally begins. This was correlated with high CD in Shiraz berries. The agrobacterium-mediated transient expression of VvBAP1 in tobacco leaves led to a decrease in electrolyte leakage and downregulated a marker gene (Hsr203J) for cell death. Expressing VvBAP1 in yeast (Saccharomyces cerevisiae) also alleviated cell death induced by hydrogen peroxide (H2O2). Overexpression of VvBAP1 in Arabidopsis increased resistance to H2O2 and reduced CD due to higher expression of genes involved in anti-oxidative responses. Arabidopsis overexpressing VvBAP1 displayed higher tolerance to drought accompanied by upregulation of antioxidant-related gene expression. VvBAP1 complemented an Arabidopsis bap1 knockout by abolishing its CD phenotypes. These results indicate that VvBAP1 may play a role in alleviating CD in grape berries and its downregulation under drought stress may be responsible for the generally observed increase in CD within the berry.
Comparison between gradient-dependent hydraulic conductivities of roots using the root pressure probe: the role of pressure propagations and implications for the relative roles of parallel radial pathways
Publisher: Wiley
Date: 04-06-2007
DOI: 10.1111/J.1365-3040.2007.01678.X
Abstract: Hydrostatic pressure relaxations with the root pressure probe are commonly used for measuring the hydraulic conductivity (Lp(r)) of roots. We compared the Lp(r) of roots from species with different root hydraulic properties (Lupinus angustifolius L. 'Merrit', Lupinus luteus L. 'Wodjil', Triticum aestivum L. 'Kulin' and Zea mays L. 'Pacific DK 477') using pressure relaxations, a pressure cl and osmotic gradients to induce water flow across the root. Only the pressure cl measures water flow under steady-state conditions. Lp(r) determined by pressure relaxations was two- to threefold greater than Lp(r) from pressure cl s and was independent of the direction of water flow. Lp(r) (pressure cl ) was two- to fourfold higher than for Lp(r) (osmotic) for all species except Triticum aestivum where Lp(r) (pressure cl ) and Lp(r) (osmotic) were not significantly different. A novel technique was developed to measure the propagation of pressure through roots to investigate the cause of the differences in Lp(r). Root segments were connected between two pressure probes so that when root pressure (P(r)) was manipulated by one probe, the other probe recorded changes in P(r). Pressure relaxations did not induce the expected kinetics in pressure in the probe at the other end of the root when axial hydraulic conductance, and probe and root capacitances were accounted for. An electric circuit model of the root was constructed that included an additional capacitance in the root loaded by a series of resistances. This accounted for the double exponential kinetics for intact roots in pressure relaxation experiments as well as the reduced response observed with the double probe experiments. Although there were potential errors with all the techniques, we considered that the measurement of Lp(r) using the pressure cl was the most unambiguous for small pressure changes, and provided that sufficient time was allowed for pressure propagation through the root. The differences in Lp(r) from different methods of measurement have implications for the models describing water transport through roots and the potential role of aquaporins.
Boron Toxicity Tolerance in Barley through Reduced Expression of the Multifunctional Aquaporin HvNIP2;1
Publisher: Oxford University Press (OUP)
Date: 25-06-2010
Abstract: Boron (B) toxicity is a significant limitation to cereal crop production in a number of regions worldwide. Here we describe the cloning of a gene from barley (Hordeum vulgare), underlying the chromosome 6H B toxicity tolerance quantitative trait locus. It is the second B toxicity tolerance gene identified in barley. Previously, we identified the gene Bot1 that functions as an efflux transporter in B toxicity-tolerant barley to move B out of the plant. The gene identified in this work encodes HvNIP2 , an aquaporin from the nodulin-26-like intrinsic protein (NIP) subfamily that was recently described as a silicon influx transporter in barley and rice (Oryza sativa). Here we show that a rice mutant for this gene also shows reduced B accumulation in leaf blades compared to wild type and that the mutant protein alters growth of yeast (Saccharomyces cerevisiae) under high B. HvNIP2 facilitates significant transport of B when expressed in Xenopus oocytes compared to controls and to another NIP (NOD26), and also in yeast plasma membranes that appear to have relatively high B permeability. We propose that tolerance to high soil B is mediated by reduced expression of HvNIP2 to limit B uptake, as well as by increased expression of Bot1 to remove B from roots and sensitive tissues. Together with Bot1, the multifunctional aquaporin HvNIP2 is an important determinant of B toxicity tolerance in barley.
GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters
Publisher: Springer Science and Business Media LLC
Date: 29-07-2015
DOI: 10.1038/NCOMMS8879
Abstract: The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms.
Determination of permeability coefficients, reflection coefficients, and hydraulic conductivity of Chara corallina using the pressure probe: Effects of solute concentrations
Publisher: Springer Science and Business Media LLC
Date: 02-1983
DOI: 10.1007/BF01870802
Mechanisms of Cl‐ transport contributing to salt tolerance
Publisher: Wiley
Date: 02-03-2010
DOI: 10.1111/J.1365-3040.2009.02060.X
Abstract: Mechanisms of Cl(-) transport in plants are poorly understood, despite the importance of minimizing Cl(-) toxicity for salt tolerance. This review summarizes Cl(-) transport processes in plants that contribute to genotypic differences in salt tolerance, identifying key traits from the cellular to whole-plant level. Key aspects of Cl(-) transport that contribute to salt tolerance in some species include reduced net xylem loading, intracellular compartmentation and greater efflux of Cl(-) from roots. We also provide an update on the biophysics of anion transport in plant cells and address issues of charge balance, selectivity and energy expenditure relevant to Cl(-) transport mechanisms. Ex les are given of anion transport systems where electrophysiology has revealed possible interactions with salinity. Finally, candidate genes for anion transporters are identified that may be contributing to Cl(-) movement within plants during salinity. This review integrates current knowledge of Cl(-) transport mechanisms to identify future pathways for improving salt tolerance.
Rapid measurement of total non-structural carbohydrate concentration in grapevine trunk and leaf tissues using near infrared spectroscopy
Publisher: Elsevier BV
Date: 04-2017
NH4 + Currents across the Peribacteroid Membrane of Soybean. Macroscopic and Microscopic Properties, Inhibition by Mg2+, and Temperature Dependence Indicate a SubpicoSiemens Channel Finely Regulated
Publisher: Oxford University Press (OUP)
Date: 23-09-2005
Abstract: The control of ammonium (NH4 +) transport is critical in preventing futile cycles of NH4 +/ammonia transport. An unusual nonselective cation channel with subpicoSiemens single-channel conductance permeable to NH4 + had previously been identified in the peribacteroid membrane (PBM) of symbiosomes from soybean (Glycine max) nodules. Here, we investigate the proposed channel mechanism and its control by luminal magnesium. Currents carried by NH4 + were measured in inside-out PBM patches by patch cl . NH4 + transport corresponding to the physiological direction of net transfer showed time-dependent activation and associated single-channel-like events. These could not be resolved to discrete conductances but had the same selectivity as the total current. The voltage dependence of the steady-state current was affected by temperature consistent with the rate constant of channel opening being reduced with decreased temperature. This resulted in steady-state currents that were more temperature sensitive at voltages where the current was only partially activated. When fully activated, the current reflected more the ion conduction through open channels and had an activation energy of 28.2 kJ mol−1 (Q10 = 1.51, 8°C–24°C). Increased Mg2+ on the symbiosome lumen side blocked the current (ID50 = 351 μ m, with 60 mm NH4 +). Complete inhibition with 2 mm Mg2+ was relieved with a small increase in NH4 + on the lumen side of the membrane (shift of 60–70 mm). With Mg2+ the selectivity of the transport for alent cations increased. From these features, we propose a alent-dependent feedback regulation of the PBM-nonselective cation channel that could maintain a constant NH4 + gradient across the membrane.
Automated estimation of leaf area index from grapevine canopies using cover photography, video and computational analysis methods
Publisher: Hindawi Limited
Date: 08-08-2014
DOI: 10.1111/AJGW.12098
Channel-Like Characteristics of the Low-Affinity Barley Phosphate Transporter PHT1;6 When Expressed in Xenopus Oocytes
Publisher: Oxford University Press (OUP)
Date: 06-01-2010
Abstract: Remobilization of inorganic phosphate (Pi) within a plant is critical for sustaining growth and seed production under external Pi fluctuation. The barley (Hordeum vulgare) transporter HvPHT1 has been implicated in Pi remobilization. In this report, we expressed HvPHT1 in Xenopus laevis oocytes, allowing detailed characterization of voltage-dependent fluxes and currents induced by HvPHT1 . HvPHT1 increased efflux of Pi near oocyte resting membrane potentials, dependent on external Pi concentration. Time-dependent inward currents were observed when membrane potentials were more negative than −160 mV, which was consistent with nH+:HPO42− (n & 2) cotransport, based on simultaneous radiotracer and oocyte voltage cl ing, dependent upon Pi concentration gradient and pH. Time- and voltage-dependent inward currents through HvPHT1 were also observed for SO42−and to a lesser degree for NO3−Cl−but not for malate. Inward and outward currents showed linear dependence on the concentration of external HPO42−similar to low-affinity Pi transport in plant studies. The electrophysiological properties of HvPHT1 , which locates to the plasma membrane when expressed in onion (Allium cepa) epidermal cells, are consistent with its suggested role in the remobilization of Pi in barley plants.
Water use of grazed salt bush plantations with saline watertable
Publisher: Elsevier BV
Date: 02-1999
Application of sprinkler cooling within the bunch zone during ripening of Cabernet Sauvignon berries to reduce the impact of high temperature
Publisher: Hindawi Limited
Date: 02-12-2017
DOI: 10.1111/AJGW.12255
Roles of Aquaporins in Root Responses to Irrigation
Publisher: Springer Science and Business Media LLC
Date: 07-2005
Engineering Strategies to Boost Crop Productivity by Cutting Respiratory Carbon Loss
Publisher: Oxford University Press (OUP)
Date: 22-01-2019
DOI: 10.1105/TPC.18.00743
Calcium delivery and storage in plant leaves: Exploring the link with water flow
Publisher: Oxford University Press (OUP)
Date: 04-2011
DOI: 10.1093/JXB/ERR111
Abstract: Calcium (Ca) is a unique macronutrient with erse but fundamental physiological roles in plant structure and signalling. In the majority of crops the largest proportion of long-distance calcium ion (Ca(2+)) transport through plant tissues has been demonstrated to follow apoplastic pathways, although this paradigm is being increasingly challenged. Similarly, under certain conditions, apoplastic pathways can dominate the proportion of water flow through plants. Therefore, tissue Ca supply is often found to be tightly linked to transpiration. Once Ca is deposited in vacuoles it is rarely redistributed, which results in highly transpiring organs amassing large concentrations of Ca ([Ca]). Meanwhile, the nutritional flow of Ca(2+) must be regulated so it does not interfere with signalling events. However, water flow through plants is itself regulated by Ca(2+), both in the apoplast via effects on cell wall structure and stomatal aperture, and within the symplast via Ca(2+)-mediated gating of aquaporins which regulates flow across membranes. In this review, an integrated model of water and Ca(2+) movement through plants is developed and how this affects [Ca] distribution and water flow within tissues is discussed, with particular emphasis on the role of aquaporins.
HvALMT1 from barley is involved in the transport of organic anions
Publisher: Oxford University Press (OUP)
Date: 22-02-2010
DOI: 10.1093/JXB/ERQ023
The wheat multi-pathogen resistance gene, Lr67res, confers a novel gain-of-function phenotype involving anion fluxes
Publisher: Cold Spring Harbor Laboratory
Date: 22-03-2022
DOI: 10.1101/2022.03.22.485337
Abstract: Partial resistance to multiple biotrophic fungal pathogens in wheat (Triticum aestivum L.) is conferred by the Lr67 gene, which encodes a Sugar Transport Protein 13 (STP13) family hexose-proton symporter variant. Two mutations (G144R, V387L) differentiate the resistant and susceptible protein variants (Lr67res and Lr67sus). The molecular function of the Lr67res protein is not well understood. We functionally characterized the wheat Lr67res protein variant using two heterologous expression systems - Xenopus laevis oocytes and Saccharomyces cerevisiae yeast. Wheat and barley (Hordeum vulgare) were used to verify disease resistance capability of Lr67/STP13 variants. The Lr67res allele, but not Lr67sus, induced large sugar-independent, anion-dominated currents in oocytes and an increased sensitivity to ions in yeast, implicating a novel gain-of-function. We demonstrate that the single mutant variant, Lr67susG144R, confers disease resistance in wheat and that transgenic barley (Hordeum vulgare L.) plants expressing the orthologous HvSTP13 gene carrying the equivalent mutations present in Lr67res exhibited increased resistance to Puccinia hordei. NaCl treatment was found to induce leaf tip necrosis in Lr67res wheat. An Lr67res-like gain-of-function can be introduced into orthologous plant hexose transporters via single amino acid mutation, highlighting the possibility of generating disease resistance in other crop species, especially with gene editing.
Adjustment of host cells for accommodation of symbiotic bacteria: Vacuole defunctionalization, HOPS suppression, and TIP1g retargeting in medicago
Publisher: Oxford University Press (OUP)
Date: 09-2014
Abstract: In legume–rhizobia symbioses, the bacteria in infected cells are enclosed in a plant membrane, forming organelle-like compartments called symbiosomes. Symbiosomes remain as in idual units and avoid fusion with lytic vacuoles of host cells. We observed changes in the vacuole volume of infected cells and thus hypothesized that microsymbionts may cause modifications in vacuole formation or function. To examine this, we quantified the volumes and surface areas of plant cells, vacuoles, and symbiosomes in root nodules of Medicago truncatula and analyzed the expression and localization of VPS11 and VPS39, members of the HOPS vacuole-tethering complex. During the maturation of symbiosomes to become N2-fixing organelles, a developmental switch occurs and changes in vacuole features are induced. For ex le, we found that expression of VPS11 and VPS39 in infected cells is suppressed and host cell vacuoles contract, permitting the expansion of symbiosomes. Trafficking of tonoplast-targeted proteins in infected symbiotic cells is also altered, as shown by retargeting of the aquaporin TIP1g from the tonoplast membrane to the symbiosome membrane. This retargeting appears to be essential for the maturation of symbiosomes. We propose that these alterations in the function of the vacuole are key events in the adaptation of the plant cell to host intracellular symbiotic bacteria.
Roles of membrane transporters: connecting the dots from sequence to phenotype
Publisher: Oxford University Press (OUP)
Date: 06-2019
DOI: 10.1093/AOB/MCZ066
Abstract: Plant membrane transporters are involved in erse cellular processes underpinning plant physiology, such as nutrient acquisition, hormone movement, resource allocation, exclusion or sequestration of various solutes from cells and tissues, and environmental and developmental signalling. A comprehensive characterization of transporter function is therefore key to understanding and improving plant performance. In this review, we focus on the complexities involved in characterizing transporter function and the impact that this has on current genomic annotations. Specific ex les are provided that demonstrate why sequence homology alone cannot be relied upon to annotate and classify transporter function, and to show how even single amino acid residue variations can influence transporter activity and specificity. Misleading nomenclature of transporters is often a source of confusion in transporter characterization, especially for people new to or outside the field. Here, to aid researchers dealing with interpretation of large data sets that include transporter proteins, we provide ex les of transporters that have been assigned names that misrepresent their cellular functions. Finally, we discuss the challenges in connecting transporter function at the molecular level with physiological data, and propose a solution through the creation of new databases. Further fundamental in-depth research on specific transport (and other) proteins is still required without it, significant deficiencies in large-scale data sets and systems biology approaches will persist. Reliable characterization of transporter function requires integration of data at multiple levels, from amino acid residue sequence annotation to more in-depth biochemical, structural and physiological studies.
Functional characterization of the rice SPX‐MFS family reveals a key role of OsSPX‐MFS1 in controlling phosphate homeostasis in leaves
Publisher: Wiley
Date: 17-07-2012
DOI: 10.1111/J.1469-8137.2012.04227.X
Abstract: • Proteins possessing the SPX domain are found in several proteins involved in inorganic phosphate (Pi) transport and signalling in yeast and plants. Although the functions of several SPX-domain protein subfamilies have recently been uncovered, the role of the SPX-MFS subfamily is still unclear. • Using quantitative RT-PCR analysis, we studied the regulation of SPX-MFS gene expression by the central regulator, OsPHR2 and Pi starvation. The function of OsSPX-MFS1 in Pi homeostasis was analysed using an OsSPX-MFS1 mutant (mfs1) and osa-miR827 overexpression line (miR827-Oe). Finally, heterologous complementation of a yeast mutant impaired in Pi transporter was used to assess the capacity of OsSPX-MFS1 to transport Pi. • Transcript analyses revealed that members of the SPX-MFS family were mainly expressed in the shoots, with OsSPX-MFS1 and OsSPX-MFS3 being suppressed by Pi deficiency, while OsSPX-MFS2 was induced. Mutation in OsSPX-MFS1 (mfs1) and overexpression of the upstream miR827 (miR827-Oe) plants impaired Pi homeostasis in the leaves. In addition, studies in yeast revealed that OsSPX-MFS1 may be involved in Pi transport. • The results suggest that OsSPX-MFS1 is a key player in maintaining Pi homeostasis in the leaves, potentially acting as a Pi transporter.
The effect of different growing conditions on water relations parameters of leaf epidermal cells of Tradescantia virginiana L.
Publisher: Springer Science and Business Media LLC
Date: 04-1984
DOI: 10.1007/BF00377383
Characterization of the TaALMT1 Protein as an Al3+-Activated Anion Channel in Transformed Tobacco (Nicotiana tabacum L.) Cells
Publisher: Oxford University Press (OUP)
Date: 02-08-2008
DOI: 10.1093/PCP/PCN107
Abstract: TaALMT1 encodes a putative transport protein associated with Al(3+)-activated efflux of malate from wheat root apices. We expressed TaALMT1 in Nicotiana tabacum L. suspension cells and conducted a detailed functional analysis. Protoplasts were isolated for patch-cl ing from cells expressing TaALMT1 and from control cells (empty vector transformed). With malate(2-) as the permeant anion in the protoplast, an inward current (anion efflux) that reversed at positive potentials was observed in protoplasts expressing TaALMT1 in the absence of Al(3+). This current was sensitive to the anion channel antagonist niflumate, but insensitive to Gd(3+). External AlCl(3) (50 microM), but not La(3+) and Gd(3+), increased the inward current in TaALMT1-transformed protoplasts. The inward current was highly selective to malate over nitrate and chloride (P(mal) >> P(NO3) >or= P(Cl), P(mal)/P(Cl) >or=18, +/-Al(3+)), under conditions with higher anion concentration internally than externally. The anion currents displayed a voltage and time dependent deactivation at negative voltages. Voltage r s revealed that inward rectification was caused by the imposed anion gradients. Single channels with conductances between 10 and 17 pS were associated with the deactivation of the current at negative voltages, agreeing with estimates from voltage r s. This study of the electrophysiological function of the TaALMT1 protein in a plant heterologous expression system provides the first direct evidence that TaALMT1 functions as an Al(3+)-activated malate(2-) channel. We show that the Al(3+)-activated currents measured in TaALMT1-transformed tobacco cells are identical to the Al(3+)-activated currents observed in the root cells of wheat, indicating that TaALMT1 alone is likely to be responsible for those endogenous currents.
Variable effects of arbuscular mycorrhizal fungal inoculation on physiological and molecular measures of root and stomatal conductance of diverse Medicago truncatula accessions
Publisher: Wiley
Date: 17-08-2019
DOI: 10.1111/PCE.13369
Abstract: Association with arbuscular mycorrhizal fungi (AMF) can impact on plant water relations mycorrhizal plants can exhibit increased stomatal conductance (g
Association between water and carbon dioxide transport in leaf plasma membranes: assessing the role of aquaporins
Publisher: Wiley
Date: 14-10-2016
DOI: 10.1111/PCE.12830
Abstract: The role of some aquaporins as CO
Characterization of an ammonium transport protein from the peribacteroid membrane of soybean nodules
Publisher: American Association for the Advancement of Science (AAAS)
Date: 21-08-1998
DOI: 10.1126/SCIENCE.281.5380.1202
Abstract: Nitrogen-fixing bacteroids in legume root nodules are surrounded by the plant-derived peribacteroid membrane, which controls nutrient transfer between the symbionts. A nodule complementary DNA ( GmSAT1 ) encoding an ammonium transporter has been isolated from soybean. GmSAT1 is preferentially transcribed in nodules and immunoblotting indicates that GmSAT1 is located on the peribacteroid membrane. [ 14 C]methylammonium uptake and patch-cl analysis of yeast expressing GmSAT1 demonstrated that it shares properties with a soybean peribacteroid membrane NH 4 + channel described elsewhere. GmSAT1 is likely to be involved in the transfer of fixed nitrogen from the bacteroid to the host.
Non‐selective cation channel activity of aquaporin AtPIP2;1 regulated by Ca2+ and pH
Publisher: Wiley
Date: 18-10-2016
DOI: 10.1111/PCE.12832
Abstract: The aquaporin AtPIP2 is an abundant plasma membrane intrinsic protein in Arabidopsis thaliana that is implicated in stomatal closure, and is highly expressed in plasma membranes of root epidermal cells. When expressed in Xenopus laevis oocytes, AtPIP2 increased water permeability and induced a non-selective cation conductance mainly associated with Na
Plant Aquaporins
Publisher: Springer International Publishing
Date: 2017
OsPAP10c, a novel secreted acid phosphatase in rice, plays an important role in the utilization of external organic phosphorus
Publisher: Wiley
Date: 09-08-2016
DOI: 10.1111/PCE.12794
Abstract: Under phosphate (Pi ) starvation, plants increase the secretion of purple acid phosphatases (PAPs) into the rhizosphere to scavenge organic phosphorus (P) for plant use. To date, only a few members of the PAP family have been characterized in crops. In this study, we identified a novel secreted PAP in rice, OsPAP10c, and investigated its role in the utilization of external organic P. OsPAP10c belongs to a monocotyledon-specific subclass of Ia group PAPs and is specifically expressed in the epidermis/exodermis cell layers of roots. Both the transcript and protein levels of OsPAP10c are strongly induced by Pi starvation. OsPAP10c overexpression increased acid phosphatase (APase) activity by more than 10-fold in the culture media and almost fivefold in both roots and leaves under Pi -sufficient and Pi -deficient conditions. This increase in APase activity further improved the plant utilization efficiency of external organic P. Moreover, several APase isoforms corresponding to OsPAP10c were identified using in-gel activity assays. Under field conditions with three different Pi supply levels, OsPAP10c-overexpressing plants had significantly higher tiller numbers and shorter plant heights. This study indicates that OsPAP10c encodes a novel secreted APase that plays an important role in the utilization of external organic P in rice.
Split personality of Aluminum Activated Malate Transporter family proteins: facilitation of both GABA and malate transport
Publisher: Cold Spring Harbor Laboratory
Date: 07-11-2017
DOI: 10.1101/215335
Abstract: Plant aluminum activated malate transporters (ALMTs) are currently classified as anion channels they are also known to be regulated by erse signals leading to a range of physiological responses. Gamma-aminobutyric acid (GABA) regulation of anion flux through ALMT proteins requires the presence of a specific amino acid motif in ALMTs that shares similarity with a GABA-binding site in mammalian GABA A receptors. Here, we explore why TaALMT1-activation leads to a negative correlation between malate efflux and endogenous GABA concentrations ([GABA] i ) in both wheat root tips and in heterologous expression systems. We show that TaALMT1 activation reduces [GABA] i because TaALMT1 facilitates GABA efflux. TaALMT1-expression also leads to GABA transport into cells, demonstrated by a yeast complementation assay and via 14C GABA uptake into TaALMT1-expressing Xenopus laevis oocytes this was found to be a general feature of all ALMTs we examined. Mutation of the GABA motif (TaALMT1 F213C ) prevented both GABA influx and efflux, and uncoupled the relationship between malate efflux and [GABA] i . We conclude that ALMTs are likely to act as both GABA and anion transporters in planta . GABA and malate appear to interact with ALMTs in a complex manner regulating each other’s transport, suggestive of a role for ALMTs in communicating metabolic status.
The feasibility of using a low-cost near-infrared, sensitive, consumer-grade digital camera mounted on a commercial UAV to assess Bambara groundnut yield
Publisher: Informa UK Limited
Date: 24-09-2021
A Survey of Barley PIP Aquaporin Ionic Conductance Reveals Ca2+-Sensitive HvPIP2;8 Na+ and K+ Conductance
Publisher: MDPI AG
Date: 27-09-2020
DOI: 10.3390/IJMS21197135
Abstract: Some plasma membrane intrinsic protein (PIP) aquaporins can facilitate ion transport. Here we report that one of the 12 barley PIPs (PIP1 and PIP2) tested, HvPIP2 , facilitated cation transport when expressed in Xenopus laevis oocytes. HvPIP2 -associated ion currents were detected with Na+ and K+, but not Cs+, Rb+, or Li+, and was inhibited by Ba2+, Ca2+, and Cd2+ and to a lesser extent Mg2+, which also interacted with Ca2+. Currents were reduced in the presence of K+, Cs+, Rb+, or Li+ relative to Na+ alone. Five HvPIP1 isoforms co-expressed with HvPIP2 inhibited the ion conductance relative to HvPIP2 alone but HvPIP1 and HvPIP1 with HvPIP2 maintained the ion conductance at a lower level. HvPIP2 water permeability was similar to that of a C-terminal phosphorylation mimic mutant HvPIP2 S285D, but HvPIP2 S285D showed a negative linear correlation between water permeability and ion conductance that was modified by a kinase inhibitor treatment. HvPIP2 transcript abundance increased in barley shoot tissues following salt treatments in a salt-tolerant cultivar Haruna-Nijo, but not in salt-sensitive I743. There is potential for HvPIP2 to be involved in barley salt-stress responses, and HvPIP2 could facilitate both water and Na+/K+ transport activity, depending on the phosphorylation status.
Root ideotype influences nitrogen transport and assimilation in maize
Publisher: Frontiers Media SA
Date: 24-04-2018
gamma-Aminobutyric acid (GABA) signalling in plants
Publisher: Springer Science and Business Media LLC
Date: 12-11-2017
DOI: 10.1007/S00018-016-2415-7
Abstract: The role of γ-aminobutyric acid (GABA) as a signal in animals has been documented for over 60 years. In contrast, evidence that GABA is a signal in plants has only emerged in the last 15 years, and it was not until last year that a mechanism by which this could occur was identified-a plant 'GABA receptor' that inhibits anion passage through the aluminium-activated malate transporter family of proteins (ALMTs). ALMTs are multigenic, expressed in different organs and present on different membranes. We propose GABA regulation of ALMT activity could function as a signal that modulates plant growth, development, and stress response. In this review, we compare and contrast the plant 'GABA receptor' with mammalian GABA
Actin filaments modulate hypoosmotic-responsive K+ efflux channels in specialised cells of developing bean seed coats
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/FP07138
Abstract: In developing bean (Phaseolus vulgaris L.) seeds, nutrients move in the symplasm from sieve elements to ground-parenchyma cells where they are transported across the plasma membrane into the seed apoplasm. Release of nutrients to the seed apoplasm is related to the osmotic conditions of the apoplasm. A hypoosmotic solution, resulting from enhanced uptake of nutrients by cotyledons, stimulates nutrient release from seed coat to the apoplasm. We investigated hypoosmotic nutrient release by examining the ionic membrane currents that respond to hypoosmotic treatment in protoplasts derived from three important cell types that occur at the seed coat–cotyledonary boundary. A non-selective but predominantly K+ efflux current that displayed a distinct time-dependent inactivation was elicited by membrane depolarisation under hypoosmotic conditions only in ground-parenchyma protoplasts. Hypoosmotic treatment had little effect on whole-cell ionic currents in protoplasts derived from coat chlorenchyma cells and cotyledon dermal cells. The inactivating K+ efflux current was elicited under isosmotic conditions by treatment with cytochalasin D, which disrupts actin filaments. Hypoosmotic treatment and cytochalasin D failed to induce the K+ current in ground-parenchyma protoplasts in the presence of the actin stabiliser, phalloidin. The net efflux of K+ from intact seed coats was enhanced by hypoosmotic treatment and cytochalasin D, and the stimulation of K+ efflux induced by the hypoosmotic treatment and cytochalasin D was abolished by phalloidin. A bursting Cl– channel previously described showed a similar pattern of responses. These results suggest that hypoosmotic-dependent KCl efflux from seed coats is mediated by the inactivating K+ outward current and bursting Cl– channel, and that actin filaments act as components of the transduction process that is a function of cell volume.
Hypoxia in grape berries: the role of seed respiration and lenticels on the berry pedicel and the possible link to cell death
Publisher: Oxford University Press (OUP)
Date: 06-03-2018
DOI: 10.1093/JXB/ERY039
Effect of water stress and elevated temperature on hypoxia and cell death in the mesocarp of Shiraz berries
Publisher: Hindawi Limited
Date: 18-07-2018
DOI: 10.1111/AJGW.12363
The identification of aluminium-resistance genes provides opportunities for enhancing crop production on acid soils
Publisher: Oxford University Press (OUP)
Date: 16-09-2010
DOI: 10.1093/JXB/ERQ272
Abstract: Acid soils restrict plant production around the world. One of the major limitations to plant growth on acid soils is the prevalence of soluble aluminium (Al(3+)) ions which can inhibit root growth at micromolar concentrations. Species that show a natural resistance to Al(3+) toxicity perform better on acid soils. Our understanding of the physiology of Al(3+) resistance in important crop plants has increased greatly over the past 20 years, largely due to the application of genetics and molecular biology. Fourteen genes from seven different species are known to contribute to Al(3+) tolerance and resistance and several additional candidates have been identified. Some of these genes account for genotypic variation within species and others do not. One mechanism of resistance which has now been identified in a range of species relies on the efflux of organic anions such as malate and citrate from roots. The genes controlling this trait are members of the ALMT and MATE families which encode membrane proteins that facilitate organic anion efflux across the plasma membrane. Identification of these and other resistance genes provides opportunities for enhancing the Al(3+) resistance of plants by marker-assisted breeding and through biotechnology. Most attempts to enhance Al(3+) resistance in plants with genetic engineering have targeted genes that are induced by Al(3+) stress or that are likely to increase organic anion efflux. In the latter case, studies have either enhanced organic anion synthesis or increased organic anion transport across the plasma membrane. Recent developments in this area are summarized and the structure-function of the TaALMT1 protein from wheat is discussed.
Correction: Corrigendum: GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters
Publisher: Springer Science and Business Media LLC
Date: 28-08-2015
DOI: 10.1038/NCOMMS9293
Abstract: Nature Communications 6, Article number: 7879 (2015) Published: 29 July 2015 Updated: 28 August 2015. The original version of this Article contained a typographical error in the spelling of the author Matthew Gilliham, which was incorrectly given as Matthew Gillham. This has now been corrected in both the PDF and HTML versions of the Article.
Ion channels in the plasma membrane of protoplasts from the halophytic angiosperm Zostera muelleri
Publisher: Springer Science and Business Media LLC
Date: 12-1994
DOI: 10.1007/BF00233443
Plant aquaporins: multifunctional water and solute channels with expanding roles
Publisher: Wiley
Date: 02-2002
DOI: 10.1046/J.0016-8025.2001.00791.X
Abstract: There is strong evidence that aquaporins are central components in plant water relations. Plant species possess more aquaporin genes than species from other kingdoms. According to sequence similarities, four major groups have been identified, which can be further ided into subgroups that may correspond to localization and transport selectivity. They may be involved in compatible solute distribution, gas-transfer (CO2, NH3) as well as in micronutrient uptake (boric acid). Recent advances in determining the structure of some aquaporins gives further details on the mechanism of selectivity. Gating behaviour of aquaporins is poorly understood but evidence is mounting that phosphorylation, pH, pCa and osmotic gradients can affect water channel activity. Aquaporins are enriched in zones of fast cell ision and expansion, or in areas where water flow or solute flux density would be expected to be high. This includes biotrophic interfaces between plants and parasites, between plants and symbiotic bacteria or fungi, and between germinating pollen and stigma. On a cellular level aquaporin clusters have been identified in some membranes. There is also a possibility that aquaporins in the endoplasmic reticulum may function in symplasmic transport if water can flow from cell to cell via the desmotubules in plasmodesmata. Functional characterization of aquaporins in the native membrane has raised doubt about the conclusiveness of expression patterns alone and need to be conducted in parallel. The challenge will be to elucidate gating on a molecular level and cellular level and to tie those findings into plant water relations on a macroscopic scale where various flow pathways need to be considered.
Energy costs of salt tolerance in crop plants
Publisher: Wiley
Date: 11-07-2019
DOI: 10.1111/NPH.15864
Abstract: Agriculture is expanding into regions that are affected by salinity. This review considers the energetic costs of salinity tolerance in crop plants and provides a framework for a quantitative assessment of costs. Different sources of energy, and modifications of root system architecture that would maximize water vs ion uptake are addressed. Energy requirements for transport of salt (NaCl) to leaf vacuoles for osmotic adjustment could be small if there are no substantial leaks back across plasma membrane and tonoplast in root and leaf. The coupling ratio of the H
3D visualisation of voids in grapevine flowers and berries using X‐ray micro computed tomography
Publisher: Hindawi Limited
Date: 06-01-2021
DOI: 10.1111/AJGW.12480
Ion channels in the plasma membrane of Amaranthus protoplasts: One cation and one anion channel dominate the conductance
Publisher: Springer Science and Business Media LLC
Date: 05-1991
DOI: 10.1007/BF01951556
Sources of water used by riparian Eucalyptus camaldulensis overlying highly saline groundwater
Publisher: Springer Science and Business Media LLC
Date: 11-1994
DOI: 10.1007/BF00317126
Structural variations in wheat HKT1;5 underpin differences in Na+ transport capacity
Publisher: Springer Science and Business Media LLC
Date: 27-11-2017
DOI: 10.1007/S00018-017-2716-5
Abstract: An important trait associated with the salt tolerance of wheat is the exclusion of sodium ions (Na
Calcium storage in plants and the implications for calcium biofortification
Publisher: Springer Science and Business Media LLC
Date: 24-07-2010
DOI: 10.1007/S00709-010-0182-0
Abstract: Calcium (Ca) is an essential nutrient for plants and animals, with key structural and signalling roles, and its deficiency in plants can result in poor biotic and abiotic stress tolerance, reduced crop quality and yield. Likewise, low Ca intake in humans has been linked to various diseases (e.g. rickets, osteoporosis, hypertension and colorectal cancer) which can threaten quality of life and have major economic costs. Biofortification of various food crops with Ca has been suggested as a good method to enhance human intake of Ca and is advocated as an economically and environmentally advantageous strategy. Efforts to enhance Ca content of crops via transgenic means have had promising results. Overall Ca content of transgenic plants has been increased but in some cases adverse affects on plant function have been observed. This suggests that a better understanding of how Ca ions (Ca(2+)) are stored and transported through plants is required to maximise the effectiveness of future approaches.
VitiCanopy: A Free Computer App to Estimate Canopy Vigor and Porosity for Grapevine
Publisher: MDPI AG
Date: 23-04-2016
DOI: 10.3390/S16040585
Feasibility study on the use of Near Infrared spectroscopy to measure water status of almond trees
Publisher: International Society for Horticultural Science (ISHS)
Date: 10-2018
Root ion channels and salinity
Publisher: Elsevier BV
Date: 11-1998
Transfer of photosynthate and naturally occurring insecticidal compounds from host plants to the root hemiparasite Santalum acuminatum (Santalaceae)
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/BT99080
Root Water Transport Under Waterlogged Conditions and the Roles of Aquaporins
Publisher: Springer Berlin Heidelberg
Date: 2010
Multiple conductances in the large K+ channel from Chara corallina shown by a transient analysis method
Publisher: Elsevier BV
Date: 03-1992
Simultaneous flux and current measurement from single plant protoplasts reveals a strong link between K+ fluxes and current, but no link between Ca2+ fluxes and current
Publisher: Wiley
Date: 08-03-2006
Cell-specific compartmentation of mineral nutrients is an essential mechanism for optimal plant productivity-another role for TPC1?
Publisher: Informa UK Limited
Date: 11-2011
A laser ablation technique maps differences in elemental composition in roots of two barley cultivars subjected to salinity stress
Publisher: Wiley
Date: 12-12-2019
DOI: 10.1111/TPJ.14599
Abstract: In saline soils, high levels of sodium (Na
The role of molybdenum in agricultural plant production
Publisher: Oxford University Press (OUP)
Date: 20-07-2005
DOI: 10.1093/AOB/MCI226
Floodwater infiltration through root channels on a sodic clay floodplain and the influence on a local tree species Eucalyptus largiflorens
Publisher: Springer Science and Business Media LLC
Date: 06-2003
ANION CHANNELS IN PLANTS
Publisher: Annual Reviews
Date: 06-1992
Arabidopsis plasma membrane intrinsic protein (AtPIP2;1) is implicated in a salinity conditional influence on seed germination
Publisher: CSIRO Publishing
Date: 06-06-2023
DOI: 10.1071/FP22260
Abstract: Dynamic changes in aquaporin gene expression occur during seed germination. One ex le is the ~30-fold increase in Arabidopsis thaliana PIP2 transcripts within 24 h of seed imbibition. To investigate whether AtPIP2 can influence seed germination wild-type Columbia-0, single (Atpip2 ) and double (Atpip2 -Atpip2 ) loss-of-function mutants, along with transgenic 2x35S::AtPIP2 over-expressing (OE) lines and null-segregant controls, were examined. The various genotypes were germinated in control and saline (75 mM NaCl treatment) conditions and tested for germination efficiency, imbibed seed maximum cross sectional (MCS) area, imbibed seed mass, and seed Na+ and K+ content. Seed lacking functional AtPIP2 and/or AtPIP2 proteins or constitutively over-expressing AtPIP2 , had delayed germination in saline conditions relative to wild-type and null-segregant seed, respectively. Exposure to saline germination conditions resulted in Atpip2 mutants having greater imbibed seed mass and less accumulated Na+ than wild-type, whereas lines over-expressing AtPIP2 had reduced imbibed seed mass and greater seed K+ content than null-segregant control seed. The results imply a role for AtPIP2 in seed germination processes, whether directly through its capacity for water and ion transport or H2O2 signalling, or indirectly through potentially triggering dynamic differential regulation of other aquaporins expressed during germination. Future research will aid in dissecting the aquaporin functions influencing germination and may lead to novel solutions for optimising germination in sub-optimal conditions, such as saline soils.
Oxygen uptake rates have contrasting responses to temperature in the root meristem and elongation zone
Publisher: Wiley
Date: 03-2022
DOI: 10.1111/PPL.13682
Abstract: Growing at either 15 or 25°C, roots of Arabidopsis thaliana , Columbia accession, produce cells at the same rate and have growth zones of the same length. To determine whether this constancy is related to energetics, we measured oxygen uptake by means of a vibrating oxygen‐selective electrode. Concomitantly, the spatial distribution of elongation was measured kinematically, delineating meristem and elongation zone. All seedlings were germinated, grown, and measured at a given temperature (15 or 25°C). Columbia was compared to lines where cell production rate roughly doubles between 15 and 25°C: Landsberg and two Columbia mutants, er‐105 and ahk3‐3 . For all genotypes and temperatures, oxygen uptake rate at any position was highest at the root cap, where mitochondrial density was maximal, based on the fluorescence of a reporter. Uptake rate declined through the meristem to plateau within the elongation zone. For oxygen uptake rate integrated over a zone, the meristem had steady‐state Q 10 values ranging from 0.7 to 2.1 by contrast, the elongation zone had values ranging from 2.6 to 3.3, implying that this zone exerts a greater respiratory demand. These results highlight a substantial energy consumption by the root cap, perhaps helpful for maintaining hypoxia in stem cells, and suggest that rapid elongation is metabolically more costly than is cell ision.
Ethylene negatively regulates aluminium-induced malate efflux from wheat roots and tobacco cells transformed with TaALMT1
Publisher: Oxford University Press (OUP)
Date: 25-03-2014
DOI: 10.1093/JXB/ERU123
Citrate-permeable channels in the plasma membrane of cluster roots from white lupin.
Publisher: Oxford University Press (OUP)
Date: 11-2004
Abstract: White lupin (Lupinus albus) is well adapted to phosphorus deficiency by developing cluster roots that release large amounts of citrate into the rhizosphere to mobilize the sparingly soluble phosphorus. To determine the mechanism underlying citrate release from cluster roots, we isolated protoplasts from different types of roots of white lupin plants grown in phosphorus-replete (+P) and phosphorus-deficient (−P) conditions and used the patch-cl technique to measure the whole-cell currents flowing across plasma membrane of these protoplasts. Two main types of anion conductance were observed in protoplasts prepared from cluster root tissue: (1) an inwardly rectifying anion conductance (IRAC) activated by membrane hyperpolarization, and (2) an outwardly rectifying anion conductance (ORAC) that became more activated with membrane depolarization. Although ORAC was an outward rectifier, it did allow substantial inward current (anion efflux) to occur. Both conductances showed citrate permeability, with IRAC being more selective for citrate3− than Cl− (PCit/PCl = 26.3), while ORAC was selective for Cl− over citrate (PCl/PCit = 3.7). Both IRAC and ORAC were sensitive to the anion channel blocker anthracene-9-carboxylic acid. These currents were also detected in protoplasts derived from noncluster roots of −P plants, as well as from normal (noncluster) roots of plants grown with 25 μm phosphorus (+P). No differences were observed in the magnitude or frequency of IRAC and ORAC currents between the cluster roots and noncluster roots of −P plants. However, the IRAC current from +P plants occurred less frequently than in the −P plants. IRAC was unaffected by external phosphate, but ORAC had reduced inward current (anion efflux) when phosphate was present in the external medium. Our data suggest that IRAC is the main pathway for citrate efflux from white lupin roots, but ORAC may also contribute to citrate efflux.
Protocol: optimising hydroponic growth systems for nutritional and physiological analysis of Arabidopsis thaliana and other plants
Publisher: Springer Science and Business Media LLC
Date: 05-02-2013
Abstract: Hydroponic growth systems are a convenient platform for studying whole plant physiology. However, we found through trialling systems as they are described in the literature that our experiments were frequently confounded by factors that affected plant growth, including algal contamination and hypoxia. We also found the way in which the plants were grown made them poorly amenable to a number of common physiological assays. The drivers for the development of this hydroponic system were: 1) the exclusion of light from the growth solution 2) to simplify the handling of in idual plants, and 3) the growth of the plant to allow easy implementation of multiple assays. These aims were all met by the use of pierced lids of black microcentrifuge tubes. Seed was germinated on a lid filled with an agar-containing germination media immersed in the same solution. Following germination, the liquid growth media was exchanged with the experimental solution, and after 14-21 days seedlings were transferred to larger tanks with aerated solution where they remained until experimentation. We provide details of the protocol including composition of the basal growth solution, and separate solutions with altered calcium, magnesium, potassium or sodium supply whilst maintaining the activity of the majority of other ions. We demonstrate the adaptability of this system for: gas exchange measurement on single leaves and whole plants qRT-PCR to probe the transcriptional response of roots or shoots to altered nutrient composition in the growth solution (we demonstrate this using high and low calcium supply) producing highly competent mesophyll protoplasts and, accelerating the screening of Arabidopsis transformants. This system is also ideal for manipulating plants for micropipette techniques such as electrophysiology or SiCSA. We present an optimised plant hydroponic culture system that can be quickly and cheaply constructed, and produces plants with similar growth kinetics to soil-grown plants, but with the advantage of being a versatile platform for a myriad of physiological and molecular biological measurements on all plant tissues at all developmental stages. We present ‘tips and tricks’ for the easy adoption of this hydroponic culture system.
Nitrate transport capacity of the Arabidopsis thaliana NRT2 family members and their interactions with AtNAR2.1
Publisher: Wiley
Date: 20-03-2012
DOI: 10.1111/J.1469-8137.2012.04094.X
Abstract: • Interactions between the Arabidopsis NitRate Transporter (AtNRT2.1) and Nitrate Assimilation Related protein (AtNAR2.1, also known as AtNRT3.1) have been well documented, and confirmed by the demonstration that AtNRT2.1 and AtNAR2.1 form a 150-kDa plasma membrane complex, thought to constitute the high-affinity nitrate transporter of Arabidopsis thaliana roots. Here, we have investigated interactions between the remaining AtNRT2 family members (AtNRT2.2 to AtNRT2.7) and AtNAR2.1, and their capacity for nitrate transport. • Three different systems were used to examine possible interactions with AtNAR2.1: membrane yeast split-ubiquitin, bimolecular fluorescence complementation in A. thaliana protoplasts and nitrate uptake in Xenopus oocytes. • All NRT2s, except for AtNRT2.7, restored growth and β-galactosidase activity in the yeast split-ubiquitin system, and split-YFP fluorescence in A. thaliana protoplasts only when co-expressed with AtNAR2.1. Thus, except for AtNRT2.7, all other NRT2 transporters interact strongly with AtNAR2.1. • Co-injection into Xenopus oocytes of cRNA of all NRT2 genes together with cRNA of AtNAR2.1 resulted in statistically significant increases of uptake over and above that resulting from single cRNA injections.
Barley Nodulin 26-like intrinsic protein permeates water, metalloids, saccharides, and ion pairs due to structural plasticity and diversification
Publisher: Elsevier BV
Date: 10-2023
A comparison of petiole hydraulics and aquaporin expression in an anisohydric and isohydric cultivar of grapevine in response to water-stress induced cavitation
Publisher: Frontiers Media SA
Date: 07-11-2017
Expression Patterns of Genes Encoding Sugar and Potassium Transport Proteins Are Simultaneously Upregulated or Downregulated When Carbon and Potassium Availability Is Modified in Shiraz (Vitis vinifera L.) Berries
Publisher: Oxford University Press (OUP)
Date: 10-07-2019
DOI: 10.1093/PCP/PCZ130
Abstract: A link between the accumulation of sugar and potassium has previously been described for ripening grape berries. The functional basis of this link has, as of yet, not been elucidated but could potentially be associated with the integral role that potassium has in phloem transport. An experiment was conducted on Shiraz grapevines in a controlled environment. The accumulation of berry sugar was curtailed by reducing the leaf photoassimilation rate, and the availability of potassium was increased through soil fertilization. The study characterizes the relationship between the accumulation of sugar and potassium into the grape berry and describes how their accumulation patterns are related to the expression patterns of their transporter proteins. A strong connection was observed between the accumulation of sugar and potassium in the grape berry pericarp, irrespective of the treatment. The relative expression of proteins associated with sugar and potassium transport across the tonoplast and plasma membrane was closely correlated, suggesting transcriptional coregulation leading to the simultaneous translocation and storage of potassium and sugar in the grape berry cell.
Nutrient loading of developing seeds
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/FP06271
Abstract: Interest in nutrient loading of seeds is fuelled by its central importance to plant reproductive success and human nutrition. Rates of nutrient loading, imported through the phloem, are regulated by transport and transfer processes located in sources (leaves, stems, reproductive structures), phloem pathway and seed sinks. During the early phases of seed development, most control is likely to be imposed by a low conductive pathway of differentiating phloem cells serving developing seeds. Following the onset of storage product accumulation by seeds, and, depending on nutrient species, dominance of path control gives way to regulation by processes located in sources (nitrogen, sulfur, minor minerals), phloem path (transition elements) or seed sinks (sugars and major mineral elements, such as potassium). Nutrients and accompanying water are imported into maternal seed tissues and unloaded from the conducting sieve elements into an extensive post-phloem symplasmic domain. Nutrients are released from this symplasmic domain into the seed apoplasm by poorly understood membrane transport mechanisms. As seed development progresses, increasing volumes of imported phloem water are recycled back to the parent plant by process(es) yet to be discovered. However, aquaporins concentrated in vascular and surrounding parenchyma cells of legume seed coats could provide a gated pathway of water movement in these tissues. Filial cells, abutting the maternal tissues, take up nutrients from the seed apoplasm by membrane proteins that include sucrose and amino acid/H+ symporters functioning in parallel with non-selective cation channels. Filial demand for nutrients, that comprise the major osmotic species, is integrated with their release and phloem import by a turgor-homeostat mechanism located in maternal seed tissues. It is speculated that turgors of maternal unloading cells are sensed by the cytoskeleton and transduced by calcium signalling cascades.
Differential fruitset between grapevine cultivars is related to differences in pollen viability and amine concentration in flowers
Publisher: Hindawi Limited
Date: 12-11-2016
DOI: 10.1111/AJGW.12191
Tissue and nitrogen-linked expression profiles of ammonium and nitrate transporters in maize
Publisher: Springer Science and Business Media LLC
Date: 20-05-2019
The role of plasma membrane intrinsic protein aquaporins in water transport through roots: Diurnal and drought stress responses reveal different strategies between isohydric and anisohydric cultivars of grapevine
Publisher: Oxford University Press (OUP)
Date: 05-11-2009
Abstract: We report physiological and anatomical characteristics of water transport across roots grown in soil of two cultivars of grapevine (Vitis vinifera) differing in response to water stress (Grenache, isohydric Chardonnay, anisohydric). Both cultivars have similar root hydraulic conductances (L o normalized to root dry weight) that change diurnally. There is a positive correlation between L o and transpiration. Under water stress, both cultivars have reduced minimum daily L o (predawn) attributed to the development of apoplastic barriers. Water-stressed and well-watered Chardonnay had the same diurnal change in litude of L o, while water-stressed Grenache showed a reduction in daily litude compared with well-watered plants. Hydraulic conductivity of root cortex cells (L pcell) doubles in Chardonnay but remains unchanged in Grenache. Of the two most highly expressed plasma membrane intrinsic protein (PIP) aquaporins in roots (VvPIP1 and VvPIP2 ), only VvPIP2 functions as a water channel in Xenopus laevis oocytes. VvPIP1 interacts with VvPIP2 to induce 3-fold higher water permeability. These two aquaporins are colocated in the root from in situ hybridization and immunolocalization of VvPIP1 and VvPIP2 subfamily members. They occur in root tip, exodermis, root cortex (detected up to 30 mm), and stele. VvPIP2 mRNA does not change diurnally or with water stress, in contrast to VvPIP1 , in which expression reflects the differences in L o and L pcell between cultivars in their responses to water stress and rewatering. VvPIP1 may regulate water transport across roots such that transpirational demand is matched by root water transport capacity. This occurs on a diurnal basis and in response to water stress that corresponds to the difference in drought tolerance between the cultivars.
Relationship between hydraulic and stomatal conductance and its regulation by root and leaf aquaporins under progressive water stress and recovery and exogenous application of ABA in Vitis vinifera
Publisher: International Society for Horticultural Science (ISHS)
Date: 11-2017
Pulsing Cl- channels in coat cells of developing bean seeds linked to hypo-osmotic turgor regulation
Publisher: Oxford University Press (OUP)
Date: 08-04-2004
DOI: 10.1093/JXB/ERH120
Non-destructive measurement of grapevine water potential using near infrared spectroscopy
Publisher: Hindawi Limited
Date: 28-12-2011
Vascular Connections Into the Grape Berry: The Link of Structural Investment to Seededness
Publisher: Frontiers Media SA
Date: 15-04-2021
Abstract: Vascular bundles in the grape pedicel and berry contain the conduits, phloem and xylem, for transport of water, sugar, nutrients and signals into and through the grape berry and play a critical role in berry growth and composition. Here, we assess the vascular anatomy within the proximal region of the berry. Guided using a 3D berry model generated by micro-CT, differential staining of transverse sections of berries and receptacles was followed by fluorescent microscopy. Morphometric and vascular characteristics were analyzed within the central proximal region (brush zone, a fibrous extension from the pedicel vascular system into the berry) of the seeded cultivars Shiraz and Sauvignon Blanc, as well as the stenospermocarpic cultivars Ruby Seedless and Flame Seedless. Observations revealed a change in vascular arrangement from the receptacle into the berry brush zone and differences in xylem element size as well as xylem and phloem area relationships. Xylem anatomical and derived hydraulic parameters, as well as total tissue area of xylem and phloem varied between cultivars and in receptacle and berry components. Variation in vascular growth between grape pedicels and berries was independent of seededness. Differences in receptacle xylem vessel size and distribution could contribute to cultivar-dependent xylem backflow constraint.
Plant hydraulics as a central hub integrating plant and ecosystem function: meeting report for ‘Emerging Frontiers in Plant Hydraulics’ (Washington, DC, May 2015)
Publisher: Wiley
Date: 20-07-2016
DOI: 10.1111/PCE.12732
Abstract: Water plays a central role in plant biology and the efficiency of water transport throughout the plant affects both photosynthetic rate and growth, an influence that scales up deterministically to the productivity of terrestrial ecosystems. Moreover, hydraulic traits mediate the ways in which plants interact with their abiotic and biotic environment. At landscape to global scale, plant hydraulic traits are important in describing the function of ecological communities and ecosystems. Plant hydraulics is increasingly recognized as a central hub within a network by which plant biology is connected to palaeobiology, agronomy, climatology, forestry, community and ecosystem ecology and earth-system science. Such grand challenges as anticipating and mitigating the impacts of climate change, and improving the security and sustainability of our food supply rely on our fundamental knowledge of how water behaves in the cells, tissues, organs, bodies and erse communities of plants. A workshop, 'Emerging Frontiers in Plant Hydraulics' supported by the National Science Foundation, was held in Washington DC, 2015 to promote open discussion of new ideas, controversies regarding measurements and analyses, and especially, the potential for expansion of up-scaled and down-scaled inter-disciplinary research, and the strengthening of connections between plant hydraulic research, allied fields and global modelling efforts.
A novel analysis of grapevine berry tissue demonstrates a variety-dependent correlation between tissue vitality and berry shrivel
Publisher: Hindawi Limited
Date: 06-2010
Effect of different host plants on the growth of the root hemiparasite Santalum acuminatum (quandong)
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/EA01093
Abstract: In recent years, the root hemiparasite Santalum acuminatum (quandong) has become an increasingly important commercial crop within the indigenous foods market. Relatively little is known of the significance of the host species on quandong growth and development. This paper presents data from a glasshouse pot experiment showing the effect of 4 different host species on the growth of quandong. Quandong growth, as measured by height and dry-mass accumulation, was significantly improved when grown in the presence of a host plant compared with being grown alone. Quandong grown with a host achieved an average height of 45 cm, while those grown alone grew up to only 37 cm. The host species also had an impact on the growth of quandong. Quandong had no detrimental effect on the growth of its host plant. Quandong grown with Myoporum parvifolium and Atriplex nummularia accumulated a significantly greater amount of dry biomass than quandong grown alone.
Transposon-Mediated Alteration of TaMATE1B Expression in Wheat Confers Constitutive Citrate Efflux from Root Apices[
Publisher: Oxford University Press (OUP)
Date: 30-11-2013
Abstract: The TaMATE1B gene (for multidrug and toxic compound extrusion) from wheat (Triticum aestivum) was isolated and shown to encode a citrate transporter that is located on the plasma membrane. TaMATE1B expression in roots was induced by iron deficiency but not by phosphorus deficiency or aluminum treatment. The coding region of TaMATE1B was identical in a genotype showing citrate efflux from root apices (cv Carazinho) to one that lacked citrate efflux (cv Egret). However, sequence upstream of the coding region differed between these two genotypes in two ways. The first difference was a single-nucleotide polymorphism located approximately 2 kb upstream from the start codon in cv Egret. The second difference was an 11.1-kb transposon-like element located 25 bp upstream of the start codon in cv Carazinho that was absent from cv Egret. The influence of these polymorphisms on TaMATE1B expression was investigated using fusions to green fluorescent protein expressed in transgenic lines of rice (Oryza sativa). Fluorescence measurements in roots of rice indicated that 1.5- and 2.3-kb regions upstream of TaMATE1B in cv Carazinho (which incorporated 3′ regions of the transposon-like element) generated 20-fold greater expression in the apical 1 mm of root compared with the native promoter in cv Egret. By contrast, fluorescence in more mature tissues was similar in both cultivars. The presence of the single-nucleotide polymorphism alone consistently generated 2-fold greater fluorescence than the cv Egret promoter. We conclude that the transposon-like element in cv Carazinho extends TaMATE1B expression to the root apex, where it confers citrate efflux and enhanced aluminum tolerance.
Maize NPF6 Proteins Are Homologs of Arabidopsis CHL1 That Are Selective for Both Nitrate and Chloride
Publisher: Oxford University Press (OUP)
Date: 08-09-2017
DOI: 10.1105/TPC.16.00724
Water relations of coral cay vegetation on the great barrier reef: Water potentials and osmotic content
Publisher: CSIRO Publishing
Date: 1984
DOI: 10.1071/BT9840449
Abstract: Foliage of 18 species from One Tree Island, a coral cay at the southern extremity of the Great Barrier Reef, contained abundant K+, Na+, Mg2+, Ca2+ and Cl-, although very high NaCl levels characteristic of halophytes were found only in Sesuvium portulacastrum. Four species contained large quantities of compatible solutes: glycinebetaine in Achyranthes aspera, proline in Sesuvium, Scaevola taccada and Melanthera biflora, and β -dimethylpropiothetin in Melanthera. The ability to make such S-containing compatible solutes as the last mentioned may be especially important for maritime species. Most of the calcium and a large proportion of the magnesium were in insoluble form in Melanthera, Argusia argentea and Pisonia grandis leaves of all three contained crystals which were shown to be Ca-rich in Pisonia. It is suggested that control of calcium levels may be particularly important in plants of highly calcareous coral cays. Predawn water potentials (Ψ) in Argusia, Pisonia and Melanthera averaged between - 0.3 and -0.8 MPa in wet weather, indicating high soil Ψ there was a daily fall of 0.5 - 1.O MPa in plant Ψ. During drought, predawn Ψ was lower in Argusia. Scaevola and Pisonia, and the daily Ψ fluctuation was small, presumably because of stomatal control of water loss. No evidence of osmotic adjustment was found in these three species. In Melanthera in drought, predawn Ψ became very low (often below -2.0 MPa) but the large daily fluctuation was still present, resulting in extremely low midday Ψ. From this and the large accumulation of solutes, especially at dry sites, it is suggested that Melanthera is capable of some osmotic adjustment.
Author response: Expression of a CO2-permeable aquaporin enhances mesophyll conductance in the C4 species Setaria viridis
Publisher: eLife Sciences Publications, Ltd
Date: 17-10-2021
Rapid shoot‐to‐root signalling regulates root hydraulic conductance via aquaporins
Publisher: Wiley
Date: 09-09-2013
DOI: 10.1111/PCE.12175
Abstract: We investigated how root hydraulic conductance (normalized to root dry weight, Lo ) is regulated by the shoot. Shoot topping (about 30% reduction in leaf area) reduced Lo of grapevine (Vitis vinifera L.), soybean (Glycine max L.) and maize (Zea mays L.) by 50 to 60%. More detailed investigations with soybean and grapevine showed that the reduction in Lo was not correlated with the reduction in leaf area, and shading or cutting single leaves had a similar effect. Percentage reduction in Lo was largest when initial Lo was high in soybean. Inhibition of Lo by weak acid (low pH) was smaller after shoot damage or leaf shading. The half time of reduction in Lo was approximately 5 min after total shoot decapitation. These characteristics indicate involvement of aquaporins. We excluded phloem-borne signals and auxin-mediated signals. Xylem-mediated hydraulic signals are possible since turgor rapidly decreased within root cortex cells after shoot topping. There was a significant reduction in the expression of several aquaporins in the plasma membrane intrinsic protein (PIP) family of both grapevine and soybean. In soybean, there was a five- to 10-fold reduction in GmPIP1 expression over 0.5-1 h which was sustained over the period of reduced Lo .
Hydraulic connection of grape berries to the vine: Varietal differences in water conductance into and out of berries, and potential for backflow
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/FP09019
Abstract: Weight loss in Vitis vinifera L. cv. Shiraz berries occurs in the later stages of ripening from 90–100 days after anthesis (DAA). This rarely occurs in varieties such as Chardonnay and Thompson seedless. Flow rates of water under a constant pressure into berries on detached bunches of these varieties are similar until 90–100 DAA. Shiraz berries then maintain constant flow rates until harvest maturity, and Chardonnay inflow tapers to almost zero. Thompson seedless maintains high xylem inflows. Hydraulic conductance for flow in and out of in idual Shiraz and Chardonnay berries was measured using a root pressure probe. From 105 DAA, during berry weight loss in Shiraz, there were significant varietal differences in xylem hydraulic conductance. Both varieties showed flow rectification such that conductance for inflow was higher than conductance for outflow. For flow into the berry, Chardonnay had 14% of the conductance of Shiraz. For flow out of the berry Chardonnay was 4% of the conductance of Shiraz. From conductance measurements for outflow from the berry and stem water potential measurements, it was calculated that Shiraz could loose ~7% of berry volume per day, consistent with rates of berry weight loss. A functional pathway for backflow from the berries to the vine via the xylem was visualised with Lucifer Yellow CH loaded at the cut stylar end of berries on potted vines. Transport of the dye out of the berry xylem ceased before 97 DAA in Chardonnay, but was still transported into the torus and pedicel xylem of Shiraz at 118 DAA. Xylem backflow could be responsible for a portion of the post-veraison weight loss in Shiraz berries. These data provide evidence of varietal differences in hydraulic connection of berries to the vine that we relate to cell vitality in the mesocarp. The key determinates of berry water relations appear to be maintenance or otherwise of semi permeable membranes in the mesocarp cells and control of flow to the xylem to give variable hydraulic connection back to the vine.
Comparative effects of deficit and partial root-zone drying irrigation techniques using moderately saline irrigation water on ion partitioning in Shiraz and Grenache grapevines
Publisher: Hindawi Limited
Date: 28-04-2016
DOI: 10.1111/AJGW.12220
Non-Invasive Tools to Detect Smoke Contamination in Grapevine Canopies, Berries and Wine: A Remote Sensing and Machine Learning Modeling Approach
Publisher: MDPI AG
Date: 30-07-2019
DOI: 10.3390/S19153335
Abstract: Bushfires are becoming more frequent and intensive due to changing climate. Those that occur close to vineyards can cause smoke contamination of grapevines and grapes, which can affect wines, producing smoke-taint. At present, there are no available practical in-field tools available for detection of smoke contamination or taint in berries. This research proposes a non-invasive/in-field detection system for smoke contamination in grapevine canopies based on predictable changes in stomatal conductance patterns based on infrared thermal image analysis and machine learning modeling based on pattern recognition. A second model was also proposed to quantify levels of smoke-taint related compounds as targets in berries and wines using near-infrared spectroscopy (NIR) as inputs for machine learning fitting modeling. Results showed that the pattern recognition model to detect smoke contamination from canopies had 96% accuracy. The second model to predict smoke taint compounds in berries and wine fit the NIR data with a correlation coefficient (R) of 0.97 and with no indication of overfitting. These methods can offer grape growers quick, affordable, accurate, non-destructive in-field screening tools to assist in vineyard management practices to minimize smoke taint in wines with in-field applications using smartphones and unmanned aerial systems (UAS).
Aquaporins: Highly Regulated Channels Controlling Plant Water Relations
Publisher: Oxford University Press (OUP)
Date: 21-01-2014
Abstract: Plant growth and development are dependent on tight regulation of water movement. Water diffusion across cell membranes is facilitated by aquaporins that provide plants with the means to rapidly and reversibly modify water permeability. This is done by changing aquaporin density and activity in the membrane, including posttranslational modifications and protein interaction that act on their trafficking and gating. At the whole organ level aquaporins modify water conductance and gradients at key “gatekeeper” cell layers that impact on whole plant water flow and plant water potential. In this way they may act in concert with stomatal regulation to determine the degree of isohydry/anisohydry. Molecular, physiological, and biophysical approaches have demonstrated that variations in root and leaf hydraulic conductivity can be accounted for by aquaporins but this must be integrated with anatomical considerations. This Update integrates these data and emphasizes the central role played by aquaporins in regulating plant water relations.
Fast activation of a time-dependent outward current in protoplasts derived from coats of developing Phaseolus vulgaris seeds
Publisher: Springer Science and Business Media LLC
Date: 17-11-2000
Abstract: An outward current that appeared to activate instantaneously in response to depolarising voltage pulses at low s ling frequencies predominated in the plasma membrane of ground-parenchyma protoplasts derived from coats of developing Phaseolus vulgaris L. (cv. Redland Pioneer) seeds. However, the outward current showed time-dependent activation when higher s ling frequencies were used to measure the current. Activation of the current was best described as a double-exponential time course with the fast and slow time constants being 1 and 20 ms, respectively. The current also exhibited a rapid deactivation that followed a double-exponential time course with time constants of approximately 2 and 30 ms, respectively. "Tail-current" analysis allowed us to show that this current exhibited a low selectivity between K- and Cl- (PK:Cl = 1.8). Such a fast-activating current may account for some of the reports of time-independent, instantaneous currents that have been observed in plasma membranes of plant cells digitised at low s ling frequencies. Therefore, when "instantaneous" currents appear it is advisable to characterise these currents using higher s ling frequencies with correspondingly higher filtering frequency cut-offs.
Effect of low oxygen concentration on the electrical properties of cortical cells of wheat roots
Publisher: Elsevier BV
Date: 1997
DOI: 10.1016/S0176-1617(97)80320-3
Abstract: Short-term effect of oxygen-deficiency on the membrane potential difference (PD), membrane resistance of cortical cells and electrical coupling between cortical cells was investigated using excised wheat roots. Hypoxia rapidly depolarised the membrane potential of the cortical cells by about 60 mV, while hypoxia had little effect on the membrane resistance of the cells. No significant change in membrane resistance by potassium channel blockers, TEA+ and verapamil, under hypoxia was observed. The electrical coupling ratio, which is a measure of plasmodesmatal resistance, between cortical cells of wheat roots was 5.9 % in aerated solution and was not affected by the low oxygen treatment, suggesting that solute transport through cytoplasmic annulus of plasmodesmata could not be affected. The possible involvement of the endoplasmic reticulum in intercellular transport of solute and water is discussed.
Computational water stress indices obtained from thermal image analysis of grapevine canopies
Publisher: Springer Science and Business Media LLC
Date: 22-08-2012
Voltage-Dependent Cation Channels Permeable to NH4 +, K+, and Ca2+ in the Symbiosome Membrane of the Model Legume Lotus japonicus
Publisher: Oxford University Press (OUP)
Date: 02-2002
DOI: 10.1104/PP.010568
Abstract: The symbiosome of nitrogen fixing root nodules mediates metabolite exchange between endosymbiotic rhizobia bacteria and the legume host. In the present study, the ion currents of the symbiosome membrane of the model legume Lotus japonicus were analyzed by patch-cl recording. Both excised and symbiosome-attached patches exhibited a large inward (toward the cytosolic side of the membrane) current that is activated in a time-dependent manner by negative (on the cytosolic side) potentials. Based on reversal potential determinations and recordings with the impermeant cationN-methyl-glucamine, this current shows a high permeability for monovalent cations with no apparent permeability for anions. The current also showed a finite Ca2+ permeability. However, the currents were predominantly carried by univalent cations with a slightly greater selectivity for NH4 +over K+. Increased Ca2+ concentration inhibited the current with a K 0.5 for inhibition of 0.317 mm. The current showed strong rectification that is mediated by alent cations (either Mg2+ or Ca2+). The influence of alent cations is symmetrical in nature, because rectification can be exerted in either direction depending upon which side of the membrane has the highest concentration of alent cations. However, based on observations with symbiosome-attached patches, the direction of the current in vivo is proposed to be toward the cytosol with cytosolic Mg2+acting as the putative gating regulator. The findings suggest thatL. japonicus possesses a voltage-dependent cation efflux channel that is capable of exporting fixed NH4 +, and may also play an additional role in Ca2+ transport.
Salinity negatively affects pollen tube growth and fruit set in grapevines and is not mitigated by silicon
Publisher: American Society for Enology and Viticulture
Date: 05-01-2016
Nonselective currents and channels in plasma membranes of protoplasts from coats of developing seeds of bean
Publisher: Oxford University Press (OUP)
Date: 02-2002
DOI: 10.1104/PP.010566
Abstract: In developing bean (Phaseolus vulgaris) seeds, phloem-imported nutrients move in the symplast from sieve elements to the ground parenchyma cells where they are transported across the plasma membrane into the seed apoplast. To study the mechanisms underlying this transport, channel currents in ground parenchyma protoplasts were characterized using patch cl . A fast-activating outward current was found in all protoplasts, whereas a slowly activating outward current was observed in approximately 25% of protoplasts. The two currents had low selectivity for univalent cations, but the slow current was more selective for K+over Cl−(P K:P Cl = 3.6–4.2) than the fast current (P K:P Cl = 1.8–2.5) and also displayed Ca2+ selectivity. The slow current was blocked by Ba2+, whereas both currents were blocked by Gd3+ and La3+. Efflux of K+ from seed coat halves was inhibited 25% by Gd3+ and La3+ but was stimulated by Ba2+ and Cs+, suggesting that only the fast current may be a component in the pathway for K+ release. An “instantaneous” inward current observed in all protoplasts exhibited similar pharmacology and permeability for univalent cations to the fast outward current. In outside-out patches, two classes of depolarization-activated cation-selective channels were observed: one slowly activating of low conductance (determined from nonstationary noise to be 2.4 pS) and another with conductances 10-fold higher. Both channels occurred at high density. The higher conductance channel in 10 mm KCl hadP K:P Cl = 2.8. Such nonselective channels in the seed coat ground parenchyma cell could function to allow some of the efflux of phloem-imported univalent ions into the seed apoplast.
Expression of a CO\textsubscript2-permeable aquaporin enhances mesophyll conductance in the C\textsubscript4 species \textitSetaria viridis
Publisher: eLife Sciences Publications, Ltd
Date: 29-11-2021
DOI: 10.7554/ELIFE.70095
Abstract: A fundamental limitation of photosynthetic carbon fixation is the availability of CO 2 . In C 4 plants, primary carboxylation occurs in mesophyll cytosol, and little is known about the role of CO 2 diffusion in facilitating C 4 photosynthesis. We have examined the expression, localization, and functional role of selected plasma membrane intrinsic aquaporins (PIPs) from Setaria italica (foxtail millet) and discovered that SiPIP2 is CO 2 -permeable. When ectopically expressed in mesophyll cells of Setaria viridis (green foxtail), SiPIP2 was localized to the plasma membrane and caused no marked changes in leaf biochemistry. Gas exchange and C 18 O 16 O discrimination measurements revealed that targeted expression of SiPIP2 enhanced the conductance to CO 2 diffusion from the intercellular airspace to the mesophyll cytosol. Our results demonstrate that mesophyll conductance limits C 4 photosynthesis at low p CO 2 and that SiPIP2 is a functional CO 2 permeable aquaporin that can improve CO 2 diffusion at the airspace/mesophyll interface and enhance C 4 photosynthesis.
Waterlogging in Australian agricultural landscapes: A review of plant responses and crop models
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/CP13080
Abstract: This review summarises reported observations of the effects of waterlogging on agricultural production in Australia and briefly discusses potential remediation strategies. Inconsistencies are demonstrated in the current indicators used for assessment of waterlogging potential across agricultural landscapes as well as in parameters measured in waterlogging studies. It is suggested that predictions of waterlogging potential for landscapes should be based on a minimum dataset that includes pedological, topographical, and climate data for the defined area, as well as observations of plant morphological appearance and visible surface water. The review also summarises the effects of low oxygen concentration in soil on rhizosphere processes, and discusses evidence for direct effects on plant physiology of reductions in soil oxygen caused by waterlogging. Finally, the review describes current crop growth, water use, and yield simulation models used in Australia (SWAGMAN, DRAINMOD, and APSIM) that incorporate waterlogging stress. It is suggested that there is scope for modifications to these models based on recent improved understanding of plant physiological responses to waterlogging and on further research. The review concludes that improvements in modelling waterlogging outcomes to assist growth and yield predictions should ultimately enhance management capacity for growers.
New potent inhibitors of aquaporins: Silver and gold compounds inhibit aquaporins of plant and human origin
Publisher: Wiley
Date: 22-10-2002
DOI: 10.1016/S0014-5793(02)03581-0
Abstract: Silver and gold compounds were tested as potential inhibitors of aquaporins of plant- and human origin. Silver as AgNO(3) or silver sulfadiazine inhibited with high potency (EC(50) 1-10 microM) the water permeability of the peribacteroid membrane from soybean (containing Nodulin 26), the water permeability of plasma membrane from roots (containing plasma membrane integral proteins), and the water permeability of human red cells (containing aquaporin 1). Gold as HAuCl(4) was less effective but still inhibited peribacteroid membrane water permeability (EC(50)=10 microM). Silver and gold are more potent inhibitors of aquaporins than the presently widely used mercury containing compounds.
Constitutive overexpression of soybean plasma membrane intrinsic protein GmPIP1;6 confers salt tolerance
Publisher: Springer Science and Business Media LLC
Date: 07-07-2014
A Barley Efflux Transporter Operates in a Na+-Dependent Manner, as Revealed by a Multidisciplinary Platform
Publisher: Oxford University Press (OUP)
Date: 15-12-2015
DOI: 10.1105/TPC.15.00625
Malate-permeable channels and cation channels activated by aluminum in the apical cells of wheat roots1
Publisher: Oxford University Press (OUP)
Date: 03-2001
Abstract: Aluminum (Al3+)-dependent efflux of malate from root apices is a mechanism for Al3+ tolerance in wheat (Triticum aestivum). The malate anions protect the sensitive root tips by chelating the toxic Al3+ cations in the rhizosphere to form non-toxic complexes. Activation of malate-permeable channels in the plasma membrane could be critical in regulating this malate efflux. We examined this by investigating Al3+-activated channels in protoplasts from root apices of near-isogenic wheat differing in Al3+ tolerance at a single locus. Using whole-cell patch cl we found that Al3+stimulated an electrical current carried by anion efflux across the plasma membrane in the Al3+-tolerant (ET8) and Al3+-sensitive (ES8) genotypes. This current occurred more frequently, had a greater current density, and remained active for longer in ET8 protoplasts than for ES8 protoplasts. The Al3+-activated current exhibited higher permeability to malate2− than to Cl−(P mal/P Cl ≥ 2.6) and was inhibited by anion channel antagonists, niflumate and diphenylamine-2-carboxylic acid. In ET8, but not ES8, protoplasts an outward-rectifying K+ current was activated in the presence of Al3+ when cAMP was included in the pipette solution. These findings provide evidence that the difference in Al3+-induced malate efflux between Al3+-tolerant and Al3+-sensitive genotypes lies in the differing capacity for Al3+ to activate malate permeable channels and cation channels for sustained malate release.
The K+/Na+ selectivity of a cation channel in the plasma membrane of root cells does not differ in salt-tolerant and salt-sensitive wheat species
Publisher: Oxford University Press (OUP)
Date: 10-1991
DOI: 10.1104/PP.97.2.598
Divalent cation gating of an ammonium permeable channel in the symbiotic membrane from soybean nodules
Publisher: Wiley
Date: 11-1998
Impact of flooding on the water use of semi-arid riparian eucalypts
Publisher: Elsevier BV
Date: 04-1998
Water Relations of the Grape Berry and Aquaporins
Publisher: BENTHAM SCIENCE PUBLISHERS
Date: 14-05-2012
Correlations between morpho-anatomical changes and radial hydraulic conductivity in roots of olive trees under water deficit and rewatering
Publisher: Oxford University Press (OUP)
Date: 07-10-2015
Abstract: The effects of prolonged drought were studied on olive (Olea europaea L. drought-sensitive cultivar Biancolilla and drought-tolerant cultivar Coratina) to examine how morpho-anatomical modifications in roots impact on root radial hydraulic conductivity (Lpr). Two-year-old self-rooted plants were subjected to a gradual water depletion. The levels of drought stress were defined by pre-dawn leaf water potentials (Ψw) of -1.5, -3.5 and -6.5 MPa. After reaching the maximum level of drought, plants were rewatered for 23 days. Progressive drought stress, for both cultivars, caused a strong reduction in Lpr (from 1.2 to 1.3 × 10(-5) m MPa(-1) s(-1) in unstressed plants to 0.2-0.6 × 10(-5) m MPa(-1) s(-1) in plants at Ψw = -6.5 MPa), particularly evident in the more suberized (brown) roots, accompanied with decreases in stomatal conductance (gs). No significant differences in Lpr and gs between the two olive cultivars were observed. Epifluorescence microscopy and image analyses revealed a parallel increase of wall suberization that doubled in white stressed roots and tripled in brown ones when compared with unstressed plants. In drought-stressed plants, the number of suberized cellular layers from the endodermis towards the cortex increased from 1-2 to 6-7. Recovery in Lpr during rewatering was correlated to the physical disruption of hydrophobic barriers, while the time necessary to obtain new mature roots likely accounted for the observed delay in the complete recovery of gs. Radial hydraulic conductivity in olive roots was strongly influenced by soil and plant water availability and it was also modulated by structural root modifications, size, growth and anatomy. These findings could be important for maintaining an optimal water status in cultivated olive trees by scheduling efficient irrigation methods, saving irrigation water and obtaining yield of high quality.
Relationships between sap flow and water potential in woody or perennial plants on islands of the Great Barrier Reef
Publisher: Wiley
Date: 08-1981
Transpiration Responses to Potential Volatile Signals and Hydraulic Failure in Single Leaves ofVitis Vinifera(CV. Shiraz) andArabidopsis Thaliana(Col 0) Utilising Sensitive Liquid Flow a
Publisher: Cold Spring Harbor Laboratory
Date: 25-01-2023
DOI: 10.1101/2023.01.24.525440
Abstract: Volatile organic compounds (VOCs) may communicate stress between plants. However little appears to be documented on how such VOCs affect transpiration. Changes in transpiration in response to some VOCs was examined by measurement of flow ( Q ) at high resolution into detached leaves of Vitis vinifera (cv. Shiraz) and Arabidopsis (Col 0). Sensors recorded arrival and decay of volatiles at the leaf lamina. Moderate xylem tensions were developed in V. vinifera leaves by incorporating a hydraulic resistance in the flow pathway. Simultaneous recording of leaf gas exchange (Assimilation, A , and Transpiration, E ) for both V. vinifera and Arabidopsis revealed that for Arabidopsis Q was stochastically restricted by the gas exchange cuvette but not E in the short term. Depending on the applied supply pressure cavitation could be controlled in V. vinifera evident from reduced Q , and leaf wilting. Stomatal closure occurred upon cavitation after a transitory increase in E and A , and after wilting began and was reversed by re-pressurization. VOCs were emitted from leaves corresponding to changes in flow rate, and light to dark transitions but not to cavitation. Volatile methanol but not ethanol or methyl salicylate induced a localised dose-dependent reversible stomatal closure in both V. vinifera and Arabidopsis.
Modified method for producing grapevine plants in controlled environments
Publisher: American Society for Enology and Viticulture
Date: 11-04-2014
Aquaporins and unloading of phloem-imported water in coats of developing bean seeds
Publisher: Wiley
Date: 17-09-2007
DOI: 10.1111/J.1365-3040.2007.01732.X
Abstract: Nutrients are imported into developing legume seeds by mass flow through the phloem, and reach developing embryos following secretion from their symplasmically isolated coats. To sustain homeostasis of seed coat water relations, phloem-delivered nutrients and water must exit seed coats at rates commensurate with those of import through the phloem. In this context, coats of developing French bean seeds were screened for expression of aquaporin genes resulting in cloning PvPIP1 , PvPIP2 and PvPIP2 . These genes were differentially expressed in all vegetative organs, but exhibited their strongest expression in seed coats. In seed coats, expression was localized to cells of the nutrient-unloading pathway. Transport properties of the PvPIPs were characterized by expression in Xenopus oocytes. Only PvPIP2 showed significant water channel activity (Pos = 150-200 microm s(-1)) even when the plasma membrane intrinsic proteins (PIPs) were co-expressed in various combinations. Permeability increases to glycerol, methylamine and urea were not detected in oocytes expressing PvPIPs. Transport active aquaporins in native plasma membranes of seed coats were demonstrated by measuring rates of osmotic shrinkage of membrane vesicles in the presence and absence of mercuric chloride and silver nitrate. The functional significance of aquaporins in nutrient and water transport in developing seeds is discussed.
Magnesium transporters, MGT2/MRS2-1 and MGT3/MRS2-5, are important for magnesium partitioning within Arabidopsis thaliana mesophyll vacuoles
Publisher: Wiley
Date: 24-01-2011
DOI: 10.1111/J.1469-8137.2010.03619.X
Abstract: See also the Commentary by Waters
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