Genomics-Assisted Breeding Strategies for Hybrid Wheat

The exploitation of heterosis in wheat holds great potential to increase yield gain and yield stability. However, the long-term success of hybrid wheat breeding is greatly dependent on the establishment of heterotic groups and the redesign of the wheat floral architecture as required for hybrid seed production. We assessed genetic diversity and phenotypic performance in a global collection of 1110 winter wheat varieties released during the past decades in 35 countries. We identified genetically distinct subgroups with potential for hybrid wheat breeding and elaborated the HyBFrame approach, a unified framework illustrating how global genetic diversity can be used to complement reciprocal recurrent selection and accelerate the development of genetically distinct heterotic groups. Furthermore, we dissected the genetic architecture underlying floral traits with relevance for hybrid wheat breeding. To this end, we employed a panel of 209 diverse winter wheat lines assessed for pollen mass and anther extrusion, and genotyped with genome-wide markers as well as for Rht-B1 and Rht-D1. The genome-wide scan revealed a complex genetic architecture underlying these traits, for which Rht-D1 was identified as the only major QTL. As a consequence, we applied genomic prediction, fitting the identified major- and medium-effect QTL as fixed effects, which yielded the highest prediction accuracies for male floral traits and outperformed marker-assisted selection. Finally, we integrated these findings in an initial concept for male pool development in wheat and demonstrate how the genomics-assisted broadening of the male pool might be achieved by our HyBFrame approach in the long run.