Genome-Wide Association Mapping of Resistance to Powdery Mildew in Regional Trials of Wheat Mainly from China

Wheat powdery mildew (Blumeria graminis f. sp. tritici [Bgt]) is a widespread disease that causes significant economic losses to common wheat (Triticum aestivum L.) crops worldwide. To identify effective resistance genes, we evaluated 120 common wheat accessions mainly from different wheat producing regions in China for responses to different Bgt isolates in the seedling stage and to natural infection in three field trials and genotyped them with a wheat 55K iSelect single-nucleotide polymorphism array for a genome-wide association study. A total of 26 loci were identified, which explained 6.6 to 26.2% of the phenotypic variation depending on individual locus. Of the 26 loci, 10 were detected in the A genomes, 10 in the B genomes, and only 6 in the D genome. Sixteen loci overlapped with known powdery mildew resistance genes or quantitative trait loci, and the remaining 10 loci were potentially novel. This study improves the understanding of the genetic structure of wheat powdery mildew resistance and provides germplasms and information on genes and markers for breeding new wheat cultivars with effective resistance to powdery mildew.