How does heterosis affect yield, quality and disease resistance in hybrid wheat?

Heterosis, or hybrid vigour, is the increased performance of a hybrid relative to the parents. The use of hybrid cultivars in maize and rice have increased the performance of these crops substantially, but the same approach has not yet been widely exploited in wheat breeding. This is largely because it has been difficult and expensive to produce hybrid wheat seeds.

Recently several genetic systems have been developed which can produce large quantities of hybrid wheat seeds, opening up the possibility to introduce hybrid wheat cultivars. These hybrid cultivars have the potential for higher grain yield, yield stability across years and improved abiotic and biotic stress tolerance compared to conventional cultivars. However the molecular basis of the improvements in agronomic performance in wheat is not well understood.

This project will test the function of major genes for yield, disease responses and grain quality in a wheat hybrid system developed by KWS. Specifically we will explore two major areas:

1) How do genes for disease resistance, yield and grain quality behave in a heterozygous state? These genes have been identified for their beneficial characteristics when they are homozygous, which is the state found in conventional breeding programmes. Heterozygosity is thought to contribute to hybrid vigour but we do not know whether these genes will retain their benefits in the heterozygous state that is likely to be present in hybrid cultivars.

2) Is the parent that donated the gene (mother or father) important for the phenotypic effect? We are very interested in wheat grains, which are the ultimate product of wheat breeding. The grain consists of both maternal tissue (the outer layers of the grain) and embryonic/endosperm tissue which contains both maternal and paternal DNA. We will investigate whether it is important to transfer grain yield and quality genes to hybrids through the mother, or whether the father can also donate these beneficial genes.

Student training:
This project will provide training in cutting-edge technologies in wheat including molecular biology, plant physiology, field-trial design, hybrid production and genomics. We will take advantage of the suite of functional genomic tools for wheat which we have developed including genome sequences (International Wheat Genome Sequencing Consortium, Science, 2018), mutant populations (Krasileva et al., PNAS, 2017) and expression atlases (Ramirez-Gonzalez et al., Science, 2018)).