Drought, plant symbionts and silicon - improving crop water relations under future climate change scenarios

Food security is threatened by the adverse effects of drought on crop yields.
Droughts are increasing in both frequency and severity, and much of global
food production relies on rain-fed agriculture, so sustainable approaches to
increasing crop resilience to drought are urgently needed. Silicon, which many
crops accumulate to high levels, has been shown to protect plants against
drought stress. The mechanisms responsible remain unclear, but one
possibility is strengthened root cell walls leading to better soil penetration,
water uptake and transport.
Arbuscular mycorrhizal fungi (AMF) form a symbiotic relationship with the
majority of land plants including most agriculturally important crop species, and
may confer a number of benefits to their host plant, including improved water
relations. They have also been shown to increase silicon uptake. However, the
abundance and diversity of AMF has declined under intensive farming methods;
if the remaining species are the ones which have the greatest beneficial
impacts on silicon uptake and plant water relations is completely unknown. The
interacting effects of AMF colonisation, rhizosphere microbial community and
silicon supply on resistance to drought stress have also not yet been studied.
This project would address this knowledge gap using innovative new
techniques to study the way silicon is deposited in plant roots, the effect this
has on plant water relations and crop yields, and how this process is affected by
the presence of AMF. It will also test whether different species of AMF affect
silicon uptake differently, and how AMF influence other components of the
microbial community and the effect of this on Si uptake.
The successful student will join a project with the potential for real world
impact in terms of improved food security and protecting crops from the
effects of climate change through novel sustainable approaches. They will

benefit from training in plant biology and ecophysiology, as well as state-of-the-
art analytical and imaging techniques, including portable X-ray florescence

spectroscopy, novel stable isotope tracking techniques and microbial

community analysis. They will also benefit from collaboration with University of
California which will use 13Carbon stable isotopes and Nano-Scale Imaging Mass
Spectrometry to track carbon movement through the individual members of
the rhizosphere community. This will provide novel insights into how drought
affects carbon allocation below ground, which components of the soil microbial
community benefit from this increased carbon and the implications for nutrient
acquisition dynamics and carbon cycling in crop systems.