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Uptake transport and speciation of elements in plant-soil-water systems in relation to bioavailability assessment

Reference	BB/C511113/1
Principal Investigator / Supervisor	Professor Stephen Paul McGrath
Co-Investigators / Co-Supervisors	Dr Jacqueline Barker, Professor Malcolm Hawkesford, Professor Philip Matthew Haygarth, Dr Fangjie Zhao
Institution	Rothamsted Research
Department	Sustainable Soils and Grassland Systems
Funding type	Research
Value (£)	84,325
Status	Completed
Type	Research Grant
Start date	15/02/2005
End date	14/11/2005
Duration	9 months

Abstract

The overall objectives are to understand the mechanisms of uptake, transport and speciation of elements in plant-soil-water systems in relation to bioavailability assessment, through multidisciplinary research utilising the wide-ranging analytical capabilities of HPLC-ICP-MS: (1) investigating genotype-phenotype relationships in trace element uptake using activation tagged Arabidopsis thaliana lines. We will investigate phenotypes with extraordinary high or low element accumulation and test their tolerance and accumulation. Those of interest will be tested under soil conditions such as low/high pH, presence of mycorrhiza and rhizosphere effect. We will determine whether exclusion or accumulation of essential or toxic elements occurs also in the reproductive parts, and whether attenuation occurs in subsequent generations; (2) evaluation of how selenium concentrations vary geographically in UK crops, and which soil factors influence their Se concentrations. Field trials on different soil types will be used to determine the required amounts and forms for Se fertilisation for cereal crops; (3) manipulating selenate uptake and metabolism in plants, by examining discrimination between sulphate and selenate uptake and distribution, and the fluxes of selenate, selenite, seleno-cysteine and seleno-methioneine in Arabidopsis using knock-out mutants with different isoforms of sulphates/selenate transporters; (4) understanding the mechanisms and evolution of arsenic hyperaccumulation. A biochemical assay using HPLC-ICP-MS will be developed to quantify the activity of arsenate reduction both in vivo and in vitro. Comparisons will be made with gene expression patterns of a putative arsenate reductase which we have cloned from Pteris vittata. Arsenic speciation studies in closely related hyperaccumulator and non-hyperaccumulator Pteris species will be linked to phylogenetic relationships; (5) Determining the labile Cu in soils for risk assessment purposes. Cu is an important contaminant that limits sustainable use of the soil. There is no useful radioisotope, therefore, we will develop the use of enriched stable isotope 65Cu followed by isotopic analysis by ICP-MS. This technique will then be applied to soils from nine unique national field experiments with sewage sludge; (6) To understand sulphur dynamics in soil-plant systems we will use both natural abundance of stable S isotopes and highly enriched 34S. The aim is to develop rapid analysis of plant and soil extracts by ICP-MS using a xenon low flow gas cell to overcome polyatomic interferences during S isotope measurements; (7) To quantify inositol-P compounds that have recently been identified in leachates from grassland soils, HPLC-ICP-MS will be used as a method of rapid measurement that does not require pre-concentration. Boron isotopes will also be used as tracers to quantify sources of contaminants in water in catchment studies. Simultaneous quantification of translocation of organometal compounds (Cu, Zn, Cd, Pb) in animal wastes and transfer to water will also be achieved with HPLC-ICP-MS.

Summary

unavailable

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	Research Equipment Initiative 2004 (RE4) [2004]
Funding Scheme	X – not Funded via a specific Funding Scheme

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