Evaluation and Genetic Architecture of Pollination Traits for Hybrdi Wheat Seed Production in United States Great Plains Germplasm

Hybrid wheat offers a 20% yield advantage an necessary as genetic gain for grain yield has stagnated. Hybrid wheat’s commercial success will hinge on reducing seed production costs by improving wheat’s outcrossing ability. In total 19 traits were measured on the 299 genotypes in the Hard Winter Wheat Association Mapping Panel with anther extrusion, pollen 50 date, plant height, and pollination duration identified as the most important traits for hybrid wheat seed production. There was significant genotypic variation for anther extrusion, pollen 50 date, and plant height while pollination duration only had significant genotypic differences in mild temperatures with genotypes responding similarly to environmental conditions. Genotype x year interactions were significant for anther extrusion, pollen 50 date, and plant height but genotypic ranks did not change among years. Anther extrusion was not correlated with plant height. Hierarchical clustering revealed that excellent pollinators tended to be early and of short to intermediate stature. This result was thought to be due to lower heat stress in early genotypes. The measurement of pollination traits can be difficult. The development of molecular tools through association mapping can speed up the selection of high outcrossing genotypes. FarmCPU was chosen as the preferred GWAS method as it was able to identify both novel and known marker trait associations. FarmCPU revealed a novel haplotype on chromosome 2A which separated the highest and lowest scoring lines for anther extrusion and would be a target for gene pyramiding. PPD-D1a had the largest effect on pollen 50 date accounting for 20% of the total variation while also being significantly associated with plant height. Rht-B1 and Rht-D1 were most important for plant height accounting for 17% of the total variation. No significant markers were identified for pollination duration. Hybrid breeders working to improve outcrossing should incorporate the novel haplotype for increased anther extrusion, pair parents based on photoperiod and reduced height genes, and select environments with low heat stress