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 agricultural 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 rhizosheaths 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. Rhizosheath mass has the potential to provide a rapid integrative screen for root hair production and functionality, particularly useful for breeding nutrient- and water-efficient crops that perform well in reduced-input agriculture. Previous research has revealed that root hairs (length, density, and morphology) and root and microbial exudates play a role in rhizosheath formation. In addition, we have shown that 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. The project will take advantage of considerable genomic and genetic resources with initial focus on two row spring barley association panel assembled from national and recommended list culitvars, with access to field trials that can be run across many environments in Europe. The project aims to understand traits and genes that control rhizosheath mass. Specifically, the candidate will

1) Undertake association studies of rhizosheath traits (root hair and exudates) to validate and extend our 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 these are influenced by environmental conditions.

3) Test the association of rhizosheath mass with plant performance under nutrient-deficit and drought in both controlled environments and in the field.

4) Develop markers for the rhizosheath trait to be tested in a prebreeding and breeding environment.