Understanding the genetics of wheat floral organ size to help feed the world

UAUY_J21DTP

Wheat provides 20% of the calories and protein consumed by humans. The world population will reach 9 billion by 2050, which requires food production to more than double. Increases in wheat yield are not meeting this demand though, partly because yield is a complex trait. The study of individual yield components, such as grain weight, is a promising route to solve this issue. We have recently cloned two transcription factors (TFs) that increase thousand grain weight and affect floral organ size in wheat. We hypothesise that understanding the mechanisms behind these effects will allow us to further modify them and identify the best strategies to deploy them into commercial wheat varieties.

The aim of this PhD project will be to investigate the mechanism underpinning the increase in grain weight by elucidating the regulatory network of these two TFs in polyploid wheat. To achieve this, we will investigate whether the two TFs are part of the same genetic pathway or whether they act on shared targets in an independent manner. We will use a series of unique genetic lines to address this hypothesis through in-depth phenotyping, microscopy and expression analyses. We will also study the changes in gene expression resulting from these novel alleles to identify their downstream targets. This will include analysing co-expression networks and testing candidate genes using available mutants.

This project provides complementary approaches to elucidating the genetic regulatory network affecting floral organ size in wheat. It allows plenty of room for the student to take ownership of the project and expand into their areas of interest and according to the results. The student will join a dynamic lab and will receive mentoring and outstanding training in modern crop genetics, genomics, data analysis and bioinformatics.

References:

Brinton J, Uauy C. 2019. A reductionist approach to dissecting grain weight and yield in wheat. Journal of Integrative Plant Biology 61:337-358

Wang W, Simmonds J, Pan Q, Davidson D, He F, Battal A, Akhunova A, Trick HN, Uauy C, Akhunov E. 2018. Gene editing and mutagenesis reveal inter-cultivar differences and additivity in the contribution of TaGW2 homoeologues to grain size and weight in wheat. Theoretical and Applied Genetics 131:2463-2475.

Brinton J, Simmonds J, Minter F, Leverington-Waite M, Snape J, Uauy C. 2017. Increased pericarp cell length underlies a major QTL for grain weight in hexaploid wheat. New Phytologist. 215:1026-1038