The Borrill lab aims to uncover the genes which control wheat grain nutrient content, with the aim to improve the nutritional value of wheat grain for human health.
The balance between yield and nutrient content
We need to increase the yields of staple crops such as wheat, to feed the growing population of the world. However, in cereal crops such as wheat, frequently there is a negative correlation between the nutritional value and the total yield of grain. Therefore, we must also consider how, in parallel to increasing yields, we can maintain or increase the protein and micronutrient content. This is essential because wheat is a major source of these nutrients to the human diet.
To escape the trade-off between yield and nutrient content the Borrill lab aims to understand the molecular mechanisms controlling nutrient remobilisation from vegetative tissues to the developing grain and the co-ordination of this process with senescence. Through knowledge of the precise molecular mechanisms we aim to identify genes which can be used to improve nutrient content, without incurring a yield penalty.
Ongoing work in the lab has identified transcription factors which regulate the senescence process. Future work will investigate the roles of these transcription factors in nutrient remobilisation and their potential to be used in wheat breeding. We will also investigate the downstream targets of these transcription factors to explore the molecular pathways regulating nutrient remobilisation in wheat.
Polyploidy and functional redundancy
All aspects of wheat biology, including the balance between yield and nutrient content, are influenced by the polyploid genome of wheat. Wheat evolved from the sequential hybridisations of three ancestral diploid species, resulting in hexaploid bread wheat, which contains three highly similar genomes. Each genome contains a highly similar set of genes, with >95 % sequence identity within coding sequencings between the homoeologs (gene copies) found on each sub-genome. However, to what extent these homoeologs have the same or different functions is currently unknown.
We recently discovered that 30 % of wheat genes have distinct expression patterns between the three homoeologs (Ramirez-Gonzalez et al., 2018, Science), and the balance of expression between homoeologs can change between tissues and wheat varieties. Future work in the lab aims to understand the functional significance of unbalanced expression between homoeologs.