Understanding the genetic control of rhizosheath and its role in tolerance to abiotic stress in barley

With global population set to hit nine billion by 2050 and the resources needed to sustain this population diminishing, unsustainable agronomic practices and environmental change have brought us to the point where a revolution in agricultural production is necessary to ensure future sustainability. A new generation of crops adapted to environmental change is needed and the key to breeding such crops is the identification and utilisation of genetic variation in yield in marginal environments. Of the traits responsible for this yield variation, those associated with roots are perceived to have great potential.

Temperate cereals produce sheaths of soil that stick to root hairs along main root axes and their lateral branches. Rhizosheath mass depends on both genetic and soil factors and has been associated with improved phosphate and water uptake.

Previous research has revealed that root hairs and root and microbial exudates play a role in rhizosheath formation. In addition, both root hair length and rhizosheath production improve resource acquisition in drought conditions. Understanding the genetic and biophysical bases of rhizosheath mass, and how these interact to influence water and nutrient uptake is now required. Rhizosheath mass has potential as a novel functional trait that can be screened rapidly to determine the genetic and physiological controls of crop tolerance to nutrient and water deficit.

Project objectives:

1) Undertake an association study of rhizosheath traits (root hair and exudates) to validate and extend preliminary data on genotypic variation in rhizosheath mass and identify candidate genes. 2) Determine the physiological roles of root hair traits and exudates in rhizosheath mass and how this is influenced by environmental conditions. 3) Test association of rhizosheath mass with plant performance under nutrient-deficit and drought in controlled environments. 4) Develop markers for the rhizosheath trait to be tested in a prebreeding environment.