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A 4 year BBSRC studentship is available to study processes involved in the mobilisation and uptake of phosphorus by plants and microbes in agricultural systems. You will use a range of methods including next generation sequencing approaches to investigate microbial communities involved in the mineralisation of soil organic phosphorus, and the extent to which these processes can be managed through selection of plant genotype to increase the sustainability of cropping systems. The student will work within a large team of PhD students and Postdoctoral workers within the School of Life Sciences at the University of Warwick. The position is linked to a major BBSRC project investigating plant-soil-microbe interactions in agricultural systems and benefits from a significant budget for laboratory work and close liaison with the agricultural industry. The studentship is available to start any time before the end of September 2013.
Globally, phosphorus (P) is a major plant-growth limiting nutrient in natural and agricultural systems. To maintain crop productivity, large amounts of inorganic phosphate (Pi) fertilisers are applied to crops. Excess fertilisers can result in losses of P, through leaching and run-off, where it contributes to eutrophication. Economically recoverable sources of phosphate rocks will be exhausted within the next 50 to 150 years which will pose a major challenge to society. Soil P exists in both organic and inorganic forms, with the relative importance of each depending on soil type and climate. Within the soil organic pool, P is mainly bound into phytic acid, phosphonates and phosphoesters. Understanding the processes controlling the dynamics of these P pools is fundamental to the development of low input, energy efficient systems in which both the input of Pi fertilisers and losses of P to the environment are reduced.
Plants acquire P as Pi from the soil solution. Although plants have the potential to produce a range of enzymes that release Pi from organic sources, their functional significance in P acquisition is uncertain. Plant organic P mobilisation capacity in crop plants could represent an vital trait in future agricultural systems. Determining the functional significance of plant derived enzymes in plant P acquisition is complicated by the presence of microbial derived enzymes in the rhizosphere.
Soil microbes produce a range of enzymes which release Pi from organic P sources. Microbes are generally assumed to be the main agents of biogeochemical cycling of P in soil. However, despite the importance of these processes for sustaining crop growth, almost nothing is known about the specific microbes responsible for these transformation processes. Consequently, the relative contribution of microbes and plants to P mineralisation in soil surrounding roots (the rhizoshere) remains to be elucidated, and represents a significant knowledge gap.
Recently, a number of organic P mineralising genes involved in turnover of phosphonates, phosphoesters and phytic acid have been identified in specific bacterial or fungal strains, providing new opportunities to identify and characterise organic P transforming microbes in the environment. In particular, there are several classes of phosphatases e.g. PhoA PhoD and PhoX, that appear to be functionally equivalen.
The aim of the current project is to determine the extent to which there is genetic variation in organo-P mobilisation capacity within oilseed rape (OSR), and to develop novel culture-independent tools for profiling organic-P mineralising microbial communities in order to determine the relative role of plants and soil microbes in organo-P mineralisation. You will develop novel molecular profiling tools to quantify the expression (real-time PCR) and diversity (454 sequencing) of phosphoesterase genes, and establish the nature of microbial communities responsible for phosphoester mineralization in the rhizosphere.
For project enquiries please contact: gary.bending@warwick.ac.uk
Funding Notes:
A stipend equivalent to UK Research Councils (at least £13,590 per annum) and Tuition fees at the UK/EU level paid in full
Applicants must meet the residence and qualification eligibility requirements set by the funder (BBSRC). Please refer to the School of Life Sciences webpage for details of the eligibility criteria.
References:
Richardson et al 2011 Plant and microbial strategies to improve the phosphorus efficiency of agriculture. Plant and Soil 39, 121-156
Research Assessment Exercise (RAE) 2008 Results