Genome-wide association study of grain shapes in Aegilops tauschii

As the diploid progenitor of the D genome of common wheat, Aegilops tauschii contains abundant genetic resources for potential economic traits, including yield, biotic and abiotic stress tolerance. In this study, phenotypic variation for 4 grain shapes in 221 Ae. tauschii accessions was evaluated in 5 environments for 2 consecutive crop seasons, and best linear unbiased estimates (BLUEs) for grain shapes were calculated across the seasons. To decrease false discovery rate, a total of 139 loci were only identified based on the BLUEs and each environment by genome-wide association study utilizing 4282 single nucleotide polymorphism (SNP) markers from D genome of wheat 55 K genotyping assay. These loci could explain 5.86-17.71% of the phenotypic variation of grain length (GL), 6.83-8.42% of grain width, 5.99-17.71% of grain perimeter, and 5.80-19.61% of grain length-width ratio (GLWR), respectively. Further, 26 significant loci were validated in the wheat mini-core collections population by two-tailed t test. Moreover, the physical positions of some loci for GL and GLWR were found to correspond with previously mapped loci that affect these traits. Based on the obtained SNP loci, 6 putative candidate genes related to grain shapes were identified. This study could provide valuable information for cloning genes related to grain shapes in Ae. tauschii.