ORCID Profile
0000-0002-7203-3763
Current Organisation
University of Adelaide Waite Campus
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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.
Plant Physiology | Plant Cell and Molecular Biology | Plant Biology | Biological Mathematics | Applied Mathematics |
Barley | Expanding Knowledge in the Biological Sciences | Wine Grapes | Expanding Knowledge in the Mathematical Sciences | Wheat
Publisher: Frontiers Media SA
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 2001
Publisher: Wiley
Date: 14-07-2000
DOI: 10.1016/S0014-5793(00)01783-X
Abstract: Mutations in the human sulphate transporter gene, DTDST, have been implicated in several diseases. Analysis of affected patients has linked disease symptoms to faulty sulphate transporter activity. We have reproduced two of these mutations in SHST1, a homologous member of the family isolated from the tropical legume, Stylosanthes hamata. Both mutations significantly reduce sulphate transport activity of SHST1. These results indicate that conserved residues between distinct members of the family may share essential roles in structure or function. The results also suggest that putative helix 9 may be important for stability and/or trafficking of SHST1 to the plasma membrane.
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/FP12290
Abstract: We aimed to identify genetic variation in root growth in the cereal crop barley (Hordeum vulgare L.) in response to the early phase of salinity stress. Seminal root elongation was examined at various concentrations of salinity in seedlings of eight barley genotypes consisting of a landrace, wild barley and cultivars. Salinity inhibited seminal root elongation in all genotypes, with considerable variation observed between genotypes. Relative root elongation rates were 60–90% and 30–70% of the control rates at 100 and 150 mM NaCl, respectively. The screen identified the wild barley genotype CPI71284–48 as the most tolerant, maintaining root elongation and biomass in response to salinity. Root elongation was most significantly inhibited in the landrace Sahara. Root and shoot Na+ concentrations increased and K+ concentrations decreased in all genotypes in response to salinity. However, the root and shoot ion concentrations did not correlate with root elongation rates, suggesting that the Na+ and K+ concentrations were not directly influencing root growth, at least during the early phase of salt stress. The identification of genetic ersity in root growth responses to salt stress in barley provides important information for future genetic, physiological and biochemical characterisation of mechanisms of salinity tolerance.
Publisher: Wiley
Date: 12-12-2019
DOI: 10.1111/TPJ.14599
Abstract: In saline soils, high levels of sodium (Na
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.
Publisher: Wiley
Date: 07-02-2000
DOI: 10.1016/S0014-5793(00)01153-4
Abstract: We have cloned and characterized the first member of a novel family of ammonium transporters in plants: AtAMT2 from Arabidopsis thaliana. AtAMT2 is more closely related to bacterial ammonium transporters than to plant transporters of the AMT1 family. The protein was expressed and functionally characterized in yeast. AtAMT2 transported ammonium in an energy-dependent manner. In contrast to transporters of the AMT1 family, however, AtAMT2 did not transport the ammonium analogue, methylammonium. AtAMT2 was expressed more highly in shoots than roots and was subject to nitrogen regulation.
Publisher: CSIRO Publishing
Date: 2000
DOI: 10.1071/BT99048
Abstract: Water relations of feral olives (Olea europaea L.) were studied on a location in the Mt Lofty Ranges, South Australia. In spring (October–November), 6 months before the study commenced, an area of trees had been cut back to stumps as part of an eradication project. The stumps resprouted vigorously over summer, similarly to regrowth seen following wildfire. The following autumn and winter, plant water potentials and soil matric potentials were measured on the cut trees and adjacent control trees, to determine whether the cut trees were better hydrated due to the pruning treatment. In autumn, before the winter rains began, the resprouting trees were more hydrated than the control trees, with a difference in predawn water potentials of between 2 and 4 MPa, and 1.5 MPa or greater throughout the day. The soil matric potential was much less negative on the cleared site, both at the surface and at 50-cm depth, indicating that soil water had been less depleted by the cut trees than by the intact trees. This improved hydration was similar to that reported for sclerophyll vegetation after defoliation by fire. Results have some significance for feral olive eradication projects.
Publisher: Elsevier BV
Date: 05-2020
Publisher: Springer Science and Business Media LLC
Date: 2002
Publisher: Oxford University Press (OUP)
Date: 05-03-2016
DOI: 10.1093/JXB/ERW059
Publisher: American Chemical Society (ACS)
Date: 15-10-2003
DOI: 10.1021/BI034827S
Abstract: The aim of this study was to identify charged amino acid residues important for activity of the sulfate transporter SHST1. We mutated 10 charged amino acids in or near proposed transmembrane helices and expressed the resulting mutants in a sulfate transport-deficient yeast strain. Mutations affecting four residues resulted in a complete loss of sulfate transport these residues were D107 and D122 in helix 1 and R354 and E366 in helix 8. All other mutants showed some reduction in transport activity. The E366Q mutant was unusual in that expression of the mutant protein was toxic to yeast cells. The R354Q mutant showed reduced trafficking to the plasma membrane, indicating that the protein was misfolded. However, transporter function (to a low level) and wild-type trafficking could be recovered by combining the R354Q mutation with either the E175Q or E270Q mutations. This suggested that R354 interacts with both E175 and E270. The triple mutant E175Q/E270Q/R354Q retained only marginal sulfate transport activity but was trafficked at wild-type levels, suggesting that a charge network between these three residues may be involved in the transport pathway, rather than in folding. D107 was also found to be essential for the ion transport pathway and may form a charge pair with R154, both of which are highly conserved. The information obtained on interactions between charged residues provides the first evidence for the possible spatial arrangement of transmembrane helices within any member of this transporter family. This information is used to develop a model for SHST1 tertiary structure.
Publisher: Informa UK Limited
Date: 12-2010
DOI: 10.3109/09687680903400120
Abstract: We have completed the first comprehensive transmembrane topology determination for a member of the ubiquitous and important SulP/SLC26 family of coupled anion transporters found in eukaryotes and prokaryotes. The prokaryotic member that we have mapped, namely BicA from Synechococcus PCC7002, is an important Na(+)-dependent bicarbonate transporter that is likely to play a major role in global primary productivity via the CO(2) concentrating mechanism in cyanobacteria. We experimentally determined the topology based on phoA-lacZ topology mapping combined with reference to a range of predictive models based on hydropathy analysis and positive charge distribution. The 12-TMH structure for BicA is characterized by tight turns between several pairs of TMH and it features a prominent cytoplasmically-located STAS domain that is characteristic of the SulP family. A key difference from previous predicted models is that we identify a cytoplasmic loop between helices 8 and 9 where previous models suggested a TMH. This region includes a highly conserved motif that defines the SulP family. The identification of this region as cytoplasmic, rather than transmembrane, has implications for the function and perhaps regulation of SulP family members. This finding is used to reinterpret mutagenesis data relating to highly conserved residues in this region from both plant and human SulP transporters.
Publisher: Frontiers Media SA
Date: 07-11-2017
Publisher: Informa UK Limited
Date: 23-06-2011
DOI: 10.3109/09687688.2011.593049
Abstract: The transporter SbtA is a high affinity Na+-dependent HCO3- uptake system present in a majority of cyanobacterial clades. It functions in conjunction with CO2 uptake systems and other HCO3- uptake systems to allow cyanobacteria to accumulate high levels of HCO3- used to support efficient photosynthetic CO2 fixation via the CO2 concentrating mechanism in these species. The phoA/lacZ fusion reporter method was used to determine the membrane topology of the cyanobacterial bicarbonate transporter, SbtA (predicted size of ∼39.7 kD), cloned from the freshwater strain, Synechocystis PCC6803. The structure conforms to a model featuring 10 transmembrane helices (TMHs), with a distinct 5+5 duplicated structure. Both the N- and C-terminus are outside the cell and the second half of the protein is inverted relative to the first. The first putative helix appears to lack sufficient topogenic signals for its correct orientation in the membrane and instead relies on the presence of later helices. The cytoplasmic loop between helices 5 and 6 is a likely location for regulatory mechanisms that could govern activation of the transporter, and the cytoplasmic loop between helices 9 and 10 also contains some conserved putative regulatory residues.
Publisher: Wiley
Date: 29-08-2020
DOI: 10.1111/NPH.15955
Abstract: Plants are inherently dynamic. Dynamics minimize stress while enabling plants to flexibly acquire resources. Three ex les are presented for plants tolerating saline soil: transport of sodium chloride (NaCl), water and macronutrients is nonuniform along a branched root water and NaCl redistribute between shoot and soil at night-time and ATP for salt exclusion is much lower in thinner branch roots than main roots, quantified using a biophysical model and geometry from anatomy. Noninvasive phenotyping and precision agriculture technologies can be used together to harness plant dynamics, but analytical methods are needed. A plant advancing in time through a soil and atmosphere space is proposed as a framework for dynamic data and their relationship to crop improvement.
Publisher: Springer Netherlands
Date: 2009
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: Wiley
Date: 29-11-2019
DOI: 10.1111/NPH.15555
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.
Start Date: 2014
End Date: 2016
Funder: Australian Research Council
View Funded ActivityStart Date: 2014
End Date: 02-2019
Amount: $394,575.00
Funder: Australian Research Council
View Funded ActivityStart Date: 07-2022
End Date: 06-2025
Amount: $489,236.00
Funder: Australian Research Council
View Funded ActivityStart Date: 09-2020
End Date: 09-2025
Amount: $420,000.00
Funder: Australian Research Council
View Funded Activity