Plant Adaptations that Increase Root-Soil Cohesion

Humans have degraded almost a quarter of vegetated land on earth, most by soil erosion. Soil loss on conventionally managed agricultural land dwarfs soil production with around 12 million fertile hectares lost annually. Plant roots produce soil cohesion, retain soil on slopes and cycle nutrients into soils, which are amongst the largest carbon sinks on earth (Lal R, Science 304: 1623). However, we don't know how roots stabilise soils; differences between species show that plant genes matter, but almost nothing is known about such genes. This ignorance could prove costly as population growth demands more food production. Climate change may compound the problem by bringing more frequent extreme weather likely to exacerbate soil loss.

In work funded by the Leverhulme Trust and SWBio DTP we have established methods to measure cohesion between Arabidopsis roots and soils. By comparing Arabidopsis mutants we have identified root traits that prevent uprooting and water erosion (two papers and a review in preparation). Our work to date identifies two important areas for further development: 1. Cohesion is a product of root-soil interaction and we need better understanding of the effectiveness and mechanisms of identified traits. 2. Plants adapt to their local environments and so far we have been testing laboratory strains, grown in compost for 60+ generations, that might have lost important traits for root-soil cohesion. The diversity of traits in natural soils is not known nor is the extent to which root traits reflect the 'native' soil.

This PhD project will address these issues. The student will discover how root-soil cohesion works, and at the same time identify and rank the importance of any root traits we might have missed. The results will identify root traits that contribute to root-soil cohesion along with mechanisms by which plants have adapted to specific properties of soils.