PhD – Manipulating the Soil Microbiome for Improved Plant Response to Nitrogen and Drought Stress


Supervisory Team: UoN: Prof Sacha Mooney, Dr Amanda Rasmussen UoA: A/Prof. Tim Cavagnaro, Dr Ron Smernik


Primary University where the student will be based: University of Adelaide Applications to:

Project Background: The frequency of extreme weather events such as drought is predicted to increase (IPPC, 2014) and yet crops in Australia and the UK are already being adversely affected. Drought not only causes water limitation, but also changes the cycling and availability of essential nutrients (especially N) in the soil (e.g. Jackson et al., 2008). In response, plants alter their root system architecture (Lynch, 2007), however, root traits for maximizing water uptake (e.g. deep roots) can be poorly adapted to acquiring nutrients and limited by sub-soil strength.

In addition the root system of cereals, such as wheat, is comprised of root types which are genetically distinct (Hochholdinger et al., 2004) and yet the functional importance for nutrient and water uptake of each type remains unknown. It is increasingly recognized that the interactions between roots and the soil microbiome heavily impact on plant growth through shaping the structure of the soil surrounding roots, controlling root-soil contact, releasing nutrients from organic matter and regulating important mechanisms like water and nutrient uptake efficiency (Daly et al., 2015). Building on joint and complementary expertise of both partners in soil ecology, soil biophysics, root science and modelling, we will explore the link between soil microbial communities, nutrient cycling and crop drought and nutrient resilience in wheat (a major crop for both countries) across a range of UK & Australian soil types.

Aims & Objectives:

1 – To determine the dynamic physiological responses leading to drought and nutrient stress tolerance in wheat varieties. Comparing nutrient and drought tolerant wheat varieties to non-tolerant varieties the student will investigate dynamic processes including nutrient and water uptake by different root classes (e.g. using labelled uptake studies) and root growth rates and responsiveness to replete and deficient nutrient/water conditions (quantified using X-ray μCT).

2 – To investigate how soil nutrient cycling and the soil microbiome influence the tolerance of selected wheat varieties to the combination of nutrient deficiency and drought stress. A range of traditional and cutting edge genomic techniques will be used to measure nutrient cycling processes and microbial community dynamics in the soil surrounding roots of tolerant and intolerant wheat varieties. This will be related to how plants respond to drought and nutrient stress. Facilities & Training: The student will receive training in several areas including imaging and modelling (recognized as vital skills for biosciences by research councils) utilizing the new state of the art Hounsfield μCT Facility (UoN) to image microscopic

3-D root-soil dynamics through space and time. This will be coupled with studies of soil nutrient cycling, genomics and plant nutrient and water uptake (UoA), under a range of future climate and nutrient availability scenarios.

Student Mobility: We anticipate a truly joint research project with the student spending an equal length of study with each partner. The initial 12 months will be at UoA, screening wheat varieties under drought and nutrient deficiency and undertaking nutrient uptake studies. The next 24 months will be based at UoN, μCT imaging the tolerant and intolerant lines for developmental dynamics of the root systems in combinations with soil microbes (e.g. mycorrhizae) selected at UoA. The final 12 months will be spent at UoA investigating the role of soil nutrient cycling and the soil microbiome, and writing up. Either institute could act as primary host, however we propose UoA as the student will start there.


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