ORCID Profile
0000-0002-9551-8755
Current Organisation
University of Adelaide
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Publisher: Frontiers Media SA
Date: 09-11-2015
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.SEMCDB.2017.08.027
Abstract: On average less than half of the applied N is captured by crops, thus there is scope and need to improve N uptake in cereals. With nitrate (NO
Publisher: Informa UK Limited
Date: 11-2010
Publisher: Springer Science and Business Media LLC
Date: 09-04-2015
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.
Publisher: Wiley
Date: 22-11-2014
DOI: 10.1111/PBI.12145
Abstract: Cereal varieties with improved salinity tolerance are needed to achieve profitable grain yields in saline soils. The expression of AVP1, an Arabidopsis gene encoding a vacuolar proton pumping pyrophosphatase (H⁺-PPase), has been shown to improve the salinity tolerance of transgenic plants in greenhouse conditions. However, the potential for this gene to improve the grain yield of cereal crops in a saline field has yet to be evaluated. Recent advances in high-throughput nondestructive phenotyping technologies also offer an opportunity to quantitatively evaluate the growth of transgenic plants under abiotic stress through time. In this study, the growth of transgenic barley expressing AVP1 was evaluated under saline conditions in a pot experiment using nondestructive plant imaging and in a saline field trial. Greenhouse-grown transgenic barley expressing AVP1 produced a larger shoot biomass compared to null segregants, as determined by an increase in projected shoot area, when grown in soil with 150 mM NaCl. This increase in shoot biomass of transgenic AVP1 barley occurred from an early growth stage and also in nonsaline conditions. In a saline field, the transgenic barley expressing AVP1 also showed an increase in shoot biomass and, importantly, produced a greater grain yield per plant compared to wild-type plants. Interestingly, the expression of AVP1 did not alter barley leaf sodium concentrations in either greenhouse- or field-grown plants. This study validates our greenhouse-based experiments and indicates that transgenic barley expressing AVP1 is a promising option for increasing cereal crop productivity in saline fields.
Publisher: Wiley
Date: 02-06-2016
DOI: 10.1111/PBI.12388
Abstract: Elucidation of the gene networks underlying the response to N supply and demand will facilitate the improvement of the N uptake efficiency of plants. We undertook a transcriptomic analysis of maize to identify genes responding to both a non-growth-limiting decrease in NO3- provision and to development-based N demand changes at seven representative points across the life cycle. Gene co-expression networks were derived by cluster analysis of the transcript profiles. The majority of NO3--responsive transcription occurred at 11 (D11), 18 (D18) and 29 (D29) days after emergence, with differential expression predominating in the root at D11 and D29 and in the leaf at D18. A cluster of 98 probe sets was identified, the expression pattern of which is similar to that of the high-affinity NO3- transporter (NRT2) genes across the life cycle. The cluster is enriched with genes encoding enzymes and proteins of lipid metabolism and transport, respectively. These are candidate genes for the response of maize to N supply and demand. Only a few patterns of differential gene expression were observed over the entire life cycle however, the composition of the classes of the genes differentially regulated at in idual time points was unique, suggesting tightly controlled regulation of NO3--responsive gene expression.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2018
DOI: 10.1007/S00425-018-3059-7
Abstract: A systematic analysis of NaCl-dependent, plasma-membrane depolarization (∆∆Ψ) in rice roots calls into question the current leading model of rapid membrane cycling of Na
Publisher: Wiley
Date: 10-2021
DOI: 10.1002/PLD3.354
Abstract: Proton‐pumping pyrophosphatases (H + ‐PPases) have been shown to enhance biomass and yield. However, to date, there has been little work towards identify genes encoding H + ‐PPases in bread wheat ( Triticum aestivum ) ( TaVP s) and limited knowledge on how the expression of these genes varies across different growth stages and tissue types. In this study, the IWGSC database was used to identify two novel TaVP genes, TaVP4 and TaVP5 , and elucidate the complete homeolog sequences of the three known TaVP genes, bringing the total number of bread wheat TaVP s from 9 to 15. Gene expression levels of each TaVP homeolog were assessed using quantitative real‐time PCR (qRT‐PCR) in four erse wheat varieties in terms of phenotypic traits related to high vacuolar pyrophosphatase expression. Homeolog expression was analyzed across multiple tissue types and developmental stages. Expression levels of the TaVP homeologs were found to vary significantly between varieties, tissues and plant developmental stages. During early development (Z10 and Z13), expressions of TaVP1 and TaVP2 homeologs were higher in shoot tissue than root tissue, with both shoot and root expression increasing in later developmental stages (Z22). TaVP2‐D was expressed in all varieties and tissue types and was the most highly expressed homeolog at all developmental stages. Expression of the TaVP3 homeologs was restricted to developing grain (Z75), while TaVP4 homeolog expression was higher at Z22 than earlier developmental stages. Variation in TaVP4B was detected among varieties at Z22 and Z75, with Buck Atlantico (high biomass) and Scout (elite Australian cultivar) having the highest levels of expression. These findings offer a comprehensive overview of the bread wheat H + ‐PPase family and identify variation in TaVP homeolog expression that will be of use to improve the growth, yield, and abiotic stress tolerance of bread wheat.
Publisher: Public Library of Science (PLoS)
Date: 06-12-2010
Publisher: Wiley
Date: 20-10-2009
Publisher: Wiley
Date: 04-2017
DOI: 10.1111/JIPB.12525
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
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
Publisher: Wiley
Date: 16-09-2016
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/FP17303
Abstract: Potato plays a key role in global food and nutritional security. Potato is an N fertiliser-responsive crop, producing high tuber yields. However, excessive use of N can result in environmental damage and high production costs, hence improving nitrogen use efficiency (NUE) of potato plants is one of the sustainable options to address these issues and increase yield. Advanced efforts have been undertaken to improve NUE in other plants like Arabidopsis, rice, wheat and maize through molecular and physiological approaches. Conversely, in potato, NUE studies have predominantly focussed on agronomy or soil management, except for a few researchers who have measured gene expression and proteins relevant to N uptake or metabolism. The focus of this review is to adapt knowledge gained from other plants to inform investigation of N metabolism and associated traits in potato with the aim of improving potato NUE using integrated genomics, physiology and breeding methods.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/FP15025
Abstract: Over 100 million tonnes of nitrogen (N) fertiliser are applied globally each year to maintain high yields in agricultural crops. The rising price of N fertilisers has made them a major cost for farmers. Inefficient use of N fertiliser leads to substantial environmental problems through contamination of air and water resources and can be a significant economic cost. Consequently, there is considerable need to improve the way N fertiliser is used in farming systems. The efficiency with which crops use applied N fertiliser – the nitrogen-use efficiency (NUE) – is currently quite low for cereals. This is the case in both high yielding environments and lower yielding environments characteristic of cereal growing regions of Australia. Multiple studies have attempted to identify the genetic basis of NUE, but the utility of the results is limited because of the complex nature of the trait and the magnitude of genotype by environment interaction. Transgenic approaches have been applied to improve plant NUE but with limited success, due, in part, to a combination of the complexity of the trait but also due to lack of accurate phenotyping methods. This review documents these two approaches and suggests future directions in improving cereal NUE with a focus on the Australian cereal industry.
Publisher: Wiley
Date: 02-03-2010
DOI: 10.1111/J.1365-3040.2009.02086.X
Abstract: Soil salinity decreases the growth rate of plants and can severely limit the productivity of crop plants. The ability to tolerate salinity stress differs widely between species of plants as well as within species. As an important component of salinity tolerance, a better understanding of the mechanisms of Na(+) transport will assist in the development of plants with improved salinity tolerance and, importantly, might lead to increased yields from crop plants growing in challenging environments. This review summarizes the current understanding of the components of Na(+) transport in glycophytic plants, including those at the soil to root interface, transport of Na(+) to the xylem, control of Na(+) loading in the stele and partitioning of the accumulated Na(+) within the shoot and in idual cells. Using this knowledge, strategies to modify Na(+) transport and engineer plant salinity tolerance, as well as areas of research which merit particular attention in order to further improve the understanding of salinity tolerance in plants, are discussed.
Publisher: Research Square Platform LLC
Date: 05-05-2020
DOI: 10.21203/RS.3.RS-25187/V1
Abstract: Background The absorption, translocation, accumulation and excretion of substances are fundamental processes in all organisms including plants, and have been successfully studied using radiotracers labelled with and since 1939. Sodium is one of the most damaging ions to the growth and productivity of crops. Due to the significance of understanding sodium transport in plants, a significant number of studies have been carried out to examine sodium influx, compartmentation, and efflux using - or 24 Na-labeled salts. Notably, however, most of these studies employed destructive methods, which has limited our understanding of sodium flux and distribution characteristics in real time, in live plants.Positron emission tomography (PET) has been used successfully in medical research and diagnosis for decades. Due to its ability to visualise and assess physiological and metabolic function, PET imaging has also begun to be employed in plant research. Here, we report the use of a clinical PET scanner with a tracer to examine -influx dynamics in barley plants ( Hordeum vulgare L. spp. vulgare – cultivar Bass) under variable nutrient levels, alterations in the day/night light cycle, and the presence of sodium channel inhibitors. Results 3D dynamic PET images of whole plants show readily visible translocation from roots to shoots in each examined plant, with rates influenced by both nutrient status and channel inhibition. PET images show that plants cultivated in low-nutrient media transport more than plants cultivated in high-nutrient media, and that uptake is suppressed in the presence of a cation-channel inhibitor. A distinct diurnal pattern of influx was discernible in curves displaying rates of change of relative radioactivity. Plants were found to absorb significantly more during the light period, and anticipate the change in the light/dark cycle by adjusting the sodium influx rate downward in the dark period, an effect not previously described experimentally. Conclusions We demonstrate the utility of clinical PET/CT scanners for real-time monitoring of the temporal dynamics of sodium transport in plants. The effects of nutrient deprivation and of ion channel inhibition on sodium influx into barley plants are shown in two proof-of-concept experiments, along with the first-ever 3D-imaging of the light and dark sodium uptake cycles in plants. This method carries significant potential for plant biology research and, in particular, in the context of genetic and treatment effects on sodium acquisition and toxicity in plants. * The authors contributed equally
Publisher: Royal Society of Chemistry (RSC)
Date: 4
DOI: 10.1039/D1MO00137J
Abstract: Quantitative phosphoproteomic analysis of rice plants grown with different levels of water supply and nitrogen supplementation revealed changes in phosphorylation of proteins involved in membrane transport, RNA processing and carbohydrate metabolism.
Publisher: Springer International Publishing
Date: 2018
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.TPLANTS.2016.11.012
Abstract: Constitutive expression of the Arabidopsis vacuolar proton-pumping pyrophosphatase (H
Publisher: Research Square Platform LLC
Date: 07-01-2021
DOI: 10.21203/RS.3.RS-25187/V3
Abstract: Background The absorption, translocation, accumulation and excretion of substances are fundamental processes in all organisms including plants, and have been successfully studied using radiotracers labelled with 11 C, 13 N, 14 C and 22 Na since 1939. Sodium is one of the most damaging ions to the growth and productivity of crops. Due to the significance of understanding sodium transport in plants, a significant number of studies have been carried out to examine sodium influx, compartmentation, and efflux using 22 Na- or 24 Na-labeled salts. Notably, however, most of these studies employed destructive methods, which has limited our understanding of sodium flux and distribution characteristics in real time, in live plants.Positron emission tomography (PET) has been used successfully in medical research and diagnosis for decades. Due to its ability to visualise and assess physiological and metabolic function, PET imaging has also begun to be employed in plant research. Here, we report the use of a clinical PET scanner with a 22 Na tracer to examine 22 Na-influx dynamics in barley plants ( Hordeum vulgare L. spp. vulgare – cultivar Bass) under variable nutrient levels, alterations in the day/night light cycle, and the presence of sodium channel inhibitors. Results 3D dynamic PET images of whole plants show readily visible 22 Na translocation from roots to shoots in each examined plant, with rates influenced by both nutrient status and channel inhibition. PET images show that plants cultivated in low-nutrient media transport more 22 Na than plants cultivated in high-nutrient media, and that 22 Na uptake is suppressed in the presence of a cation-channel inhibitor. A distinct diurnal pattern of 22 Na influx was discernible in curves displaying rates of change of relative radioactivity. Plants were found to absorb more 22 Na during the light period, and anticipate the change in the light/dark cycle by adjusting the sodium influx rate downward in the dark period, an effect not previously described experimentally. Conclusions We demonstrate the utility of clinical PET/CT scanners for real-time monitoring of the temporal dynamics of sodium transport in plants. The effects of nutrient deprivation and of ion channel inhibition on sodium influx into barley plants are shown in two proof-of-concept experiments, along with the first-ever 3D-imaging of the light and dark sodium uptake cycles in plants. This method carries significant potential for plant biology research and, in particular, in the context of genetic and treatment effects on sodium acquisition and toxicity in plants.
Publisher: Research Square Platform LLC
Date: 03-11-2020
DOI: 10.21203/RS.3.RS-25187/V2
Abstract: Background The absorption, translocation, accumulation and excretion of substances are fundamental processes in all organisms including plants, and have been successfully studied using radiotracers labelled with 11 C, 13 N, 14 C and 22 Na since 1939. Sodium is one of the most damaging ions to the growth and productivity of crops. Due to the significance of understanding sodium transport in plants, a significant number of studies have been carried out to examine sodium influx, compartmentation, and efflux using 22 Na- or 24 Na-labeled salts. Notably, however, most of these studies employed destructive methods, which has limited our understanding of sodium flux and distribution characteristics in real time, in live plants.Positron emission tomography (PET) has been used successfully in medical research and diagnosis for decades. Due to its ability to visualise and assess physiological and metabolic function, PET imaging has also begun to be employed in plant research. Here, we report the use of a clinical PET scanner with a 22 Na tracer to examine 22 Na-influx dynamics in barley plants ( Hordeum vulgare L. spp. vulgare – cultivar Bass) under variable nutrient levels, alterations in the day/night light cycle, and the presence of sodium channel inhibitors. Results 3D dynamic PET images of whole plants show readily visible 22 Na translocation from roots to shoots in each examined plant, with rates influenced by both nutrient status and channel inhibition. PET images show that plants cultivated in low-nutrient media transport more 22 Na than plants cultivated in high-nutrient media, and that 22 Na uptake is suppressed in the presence of a cation-channel inhibitor. A distinct diurnal pattern of 22 Na influx was discernible in curves displaying rates of change of relative radioactivity. Plants were found to absorb more 22 Na during the light period, and anticipate the change in the light/dark cycle by adjusting the sodium influx rate downward in the dark period, an effect not previously described experimentally. Conclusions We demonstrate the utility of clinical PET/CT scanners for real-time monitoring of the temporal dynamics of sodium transport in plants. The effects of nutrient deprivation and of ion channel inhibition on sodium influx into barley plants are shown in two proof-of-concept experiments, along with the first-ever 3D-imaging of the light and dark sodium uptake cycles in plants. This method carries significant potential for plant biology research and, in particular, in the context of genetic and treatment effects on sodium acquisition and toxicity in plants.
Publisher: Springer Science and Business Media LLC
Date: 10-08-2016
DOI: 10.1007/S11103-016-0512-5
Abstract: We found metabolites, enzyme activities and enzyme transcript abundances vary significantly across the maize lifecycle, but weak correlation exists between the three groups. We identified putative genes regulating nitrate assimilation. Progress in improving nitrogen (N) use efficiency (NUE) of crop plants has been h ered by the complexity of the N uptake and utilisation systems. To understand this complexity we measured the activities of seven enzymes and ten metabolites related to N metabolism in the leaf and root tissues of Gaspe Flint maize plants grown in 0.5 or 2.5 mM NO3 (-) throughout the lifecycle. The amino acids had remarkably similar profiles across the lifecycle except for transient responses, which only appeared in the leaves for aspartate or in the roots for asparagine, serine and glycine. The activities of the enzymes for N assimilation were also coordinated to a certain degree, most noticeably with a peak in root activity late in the lifecycle, but with wide variation in the activity levels over the course of development. We analysed the transcriptional data for gene sets encoding the measured enzymes and found that, unlike the enzyme activities, transcript levels of the corresponding genes did not exhibit the same coordination across the lifecycle and were only weakly correlated with the levels of various amino acids or in idual enzyme activities. We identified gene sets which were correlated with the enzyme activity profiles, including seven genes located within previously known quantitative trait loci for enzyme activities and hypothesise that these genes are important for the regulation of enzyme activities. This work provides insights into the complexity of the N assimilation system throughout development and identifies candidate regulatory genes, which warrant further investigation in efforts to improve NUE in crop plants.
Publisher: Elsevier
Date: 2017
Publisher: Wiley
Date: 10-2014
DOI: 10.1111/TPJ.12651
Abstract: Bread wheat (Triticum aestivum L.) has a major salt tolerance locus, Kna1, responsible for the maintenance of a high cytosolic K(+) /Na(+) ratio in the leaves of salt stressed plants. The Kna1 locus encompasses a large DNA fragment, the distal 14% of chromosome 4DL. Limited recombination has been observed at this locus making it difficult to map genetically and identify the causal gene. Here, we decipher the function of TaHKT1 -D, a candidate gene underlying the Kna1 locus. Transport studies using the heterologous expression systems Saccharomyces cerevisiae and Xenopus laevis oocytes indicated that TaHKT1 -D is a Na(+) -selective transporter. Transient expression in Arabidopsis thaliana mesophyll protoplasts and in situ polymerase chain reaction indicated that TaHKT1 -D is localised on the plasma membrane in the wheat root stele. RNA interference-induced silencing decreased the expression of TaHKT1 -D in transgenic bread wheat lines which led to an increase in the Na(+) concentration in the leaves. This indicates that TaHKT1 -D retrieves Na(+) from the xylem vessels in the root and has an important role in restricting the transport of Na(+) from the root to the leaves in bread wheat. Thus, TaHKT1 -D confers the essential salinity tolerance mechanism in bread wheat associated with the Kna1 locus via shoot Na(+) exclusion and is critical in maintaining a high K(+) /Na(+) ratio in the leaves. These findings show there is potential to increase the salinity tolerance of bread wheat by manipulation of HKT1 genes.
Publisher: Oxford University Press (OUP)
Date: 06-02-2020
DOI: 10.1093/JXB/ERAA049
Abstract: Water and nitrogen availability limit crop productivity globally more than most other environmental factors. Plant availability of macronutrients such as nitrate is, to a large extent, regulated by the amount of water available in the soil, and, during drought episodes, crops can become simultaneously water and nitrogen limited. In this review, we explore the intricate relationship between water and nitrogen transport in plants, from transpiration-driven mass flow in the soil to uptake by roots via membrane transporters and channels and transport to aerial organs. We discuss the roles of root architecture and of suberized hydrophobic root barriers governing apoplastic water and nitrogen movement into the vascular system. We also highlight the need to identify the signalling cascades regulating water and nitrogen transport, as well as the need for targeted physiological analyses of plant traits influencing water and nitrogen uptake. We further advocate for incorporation of new phenotyping technologies, breeding strategies, and agronomic practices to improve crop yield in water- and nitrogen-limited production systems.
Publisher: Springer International Publishing
Date: 2018
Publisher: Elsevier BV
Date: 2011
DOI: 10.1093/MP/SSQ056
Abstract: Elevated salinity imposes osmotic and ion toxicity stresses on living cells and requires a multitude of responses in order to enable plant survival. Building on earlier work profiling transcript levels in rice (Oryza sativa) shoots of FL478, a salt-tolerant indica recombinant inbred line, and IR29, a salt-sensitive cultivar, transcript levels were compared in roots of these two accessions as well as in the roots of two additional salt-tolerant indica genotypes, the landrace Pokkali and the recombinant inbred line IR63731. The aim of this study was to compare transcripts in the sensitive and the tolerant lines in order to identify genes likely to be involved in plant salinity tolerance, rather than in responses to salinity per se. Transcript profiles of several gene families with known links to salinity tolerance are described (e.g. HKTs, NHXs). The putative function of a set of genes identified through their salt responsiveness, transcript levels, and/or chromosomal location (i.e. underneath QTLs for salinity tolerance) is also discussed. Finally, the parental origin of the Saltol region in FL478 is further investigated. Overall, the dataset presented appears to be robust and it seems likely that this system could provide a reliable strategy for the discovery of novel genes involved in salinity tolerance.
Publisher: Wiley
Date: 29-11-2019
DOI: 10.1111/NPH.15555
No related grants have been discovered for Darren Plett.