Inheritance of gene expression in polyploid wheat

Many of the world's major crops are polyploid including wheat, which is a staple crop for 2.5 billion people. The wheat genome contains three copies of most genes, known as homoeologs (copies of the gene from the A, B and D genomes, together constituting one triad). Homoeologs have been proposed to confer adaptive advantages in polyploids, for example through tissue specific expression. However to take advantage of the flexibility that homoeologs afford the wheat genome to increase food production, we need to understand how the three homoeologs are regulated. Several major agronomic traits are controlled by changes in the expression level of one homoeolog including VRN1 and PPD1 that have been essential to adapt wheat flowering to a range of environmental conditions. These well-studied genes are not unique in showing differences in the expression levels of homoeologs. We recently found that homoeologs in ~30% of triads differ in their expression levels, i.e. one homoeolog is over or under expressed compared to the other two gene copies. Furthermore, ~30% of triads change their homoeolog expression between wheat varieties and our preliminary data shows that differences in homoeolog expression can be inherited. In this project, we will explore the genetic and epigenetic factors which influence the inheritance of homoeolog expression. We will discover fundamental information about the control of gene expression in polyploid wheat and identify potential routes to manipulate homoeolog expression that may also be applicable to other polyploid crops of agronomic importance.