How does soil microbial diversity impact upon above-ground drought tolerance in plants?

Microbes perform several key roles in soils including in the supply of many
nutrients through the degradation of soil organic matter, and can contribute to
the release of many potent greenhouse gases that contribute to global climate
change. Hence, there is much current interest in the understanding the soil
microbiome. The soil microbial community is taxonomically rich but at present
most of this is known principally from a DNA sequence, from which function
cannot be ascribed. Thus, it is essential to establish whether there are similar
links between microbial diversity and function as are found in other above-
ground organisms.

One key group of soil microorganisms is that of the arbuscular mycorrhizal fungi
(AMF; phylum Glomeromycota). AMF are both ubiquitous and abundant
representing perhaps 10% or more of the soil microbial biomass. AMF form a
symbiotic relationship with two-thirds of all land plants. In return for plant
carbon, AMF confer a number of benefits to their host plant including enhanced
uptake of nutrients, increased resistance to pathogens and improved water
relations. Given the large number of potential hosts compared to a relatively
small size of described AMF species it was traditionally assumed that all AMF
performed essentially in the same way. However, different AMF can benefit
different hosts to varying extents. Moreover, roots of a single plant can be
colonised by multiple AMF and a single AMF can connect several plant species
together through its mycelium, resulting in complex interactions among
organisms both above- and below-ground.

This project will examine the impact of increasing AMF diversity upon water
relations in the host plant under contrasting drought regimes. Climate change
models predict that drought periods will become both more frequent and
severe and therefore plants may have to depend increasingly upon their AMF
partner to help acquire the water they need. However, we do not know if AMF
differ in their capability to improve drought tolerance or what impact an
increase in AMF diversity may have or if there is redundancy within the system.

The student will conduct microcosm experiments, where water availability and
AMF richness and composition will be manipulated. The student will thus have
the opportunity to study how the diversity of the key ecosystem engineers AMF
affects above-ground processes under environmental change. The student will
be trained in a wide range of state-of-the-art physiological and genomic
techniques.