Association mapping for yield and yield-contributing traits in barley under drought conditions with genome-based SSR markers

Drought negatively affects plant development, growth, yield, and ultimately production of crop species. Association analysis of yield and yield-contributing traits was conducted for a barley germplasm collection consisting 107 wild (Hordeum spontaneum L.) genotypes, originating from 12 countries using 76 SSR markers. Phenotypic evaluations were performed for days to heading, plant height, number of tillers/plant, spike length, thousand kernel weight, single plant yield under well-watered and drought-stress conditions. Highly significant differences between well-watered and drought-stress conditions were observed in all measured traits. Association analysis revealed a total of 83 significant marker-trait associations for all six measured traits. The results revealed that several chromosomal regions significantly influence more than one trait, suggesting a possible existence of pleiotropic or indirect effects. The phenotypic variation explained by individual marker-trait associations ranged from 5.08 to 27.84%. The results demonstrated that wild barley is a valuable source for improving yield and yield-contributing traits for drought tolerance. Our data provide a tool kit for the potential application of marker-assisted selection for drought tolerance in barley.