Using genome wide association studies of rice straw digestibility and silica content to produce more sustainable biofuels

Globally hundreds of millions of tons of rice straw are burned in the field every year. Straw burning generates significant atmospheric pollution, leading to premature deaths and losses in crop productivity, and contributing to global warming. Rice straw is burned because it is considered a waste product of agriculture, but it is potentially a rich source of polysaccharides that could be used to produce biofuels or be used as animal feed. The problem is that these sustainable uses are largely ignored because rice straw is hard to digest and has a high content of silica. The aim of the project is to empower the development of low silica, high digestibility straw in elite rice cultivars, so that the straw can be used for biofuel production or animal feed.

We have developed a rice genetic diversity panel, in association with colleagues in Vietnam, and have generated high density single nucleotide polymorphism maps for genome wide association studies to identify quantitative trait loci (QTL) linked to improved digestibility and lower silica content and lignin content.

The objectives of the studentship are to identify the causative genes underlying these QTL for digestibility and silica content. This will be achieved using a range of molecular genetic and molecular biological methods that will include:
• Identifying QTL for digestibility and silica content
• Refining QTL regions using crosses made from selected rice lines
• Using insertion mutants or genome editing to assess the function of candidate genes
• Producing recombinant enzymes from candidate gene coding sequences and characterizing their biochemical activity
• Working with colleagues in Vietnam to identify genetic markers to improve rice straw quality
The proposed work is highly novel and will take the work in our group on biomass digestibility into new areas exploring the role of silica in plant cell walls. The proposed work is very timely, as we badly need to reduce the negative impacts of human activity on the environment as well as generate sustainable biofuels that do not negatively impact on global food security.

The successful student will receive training in state-of-the art molecular techniques, combined with plant biology and environmental sustainability, all within an experimental system with the potential for real world impact in food security. They would gain experience of a range of disciplines, including molecular genetics, biotechnology and plant chemical analysis, and will be trained in a range of techniques, including GWAS, genome editing and portable X-ray fluorescence spectroscopy.