Diagnostic Kompetitive Allele-Specific PCR Markers of Wheat Broad-Spectrum Powdery Mildew Resistance Genes , , and Developed for High-Throughput Marker-Assisted Selection.

Wheat powdery mildew is a devastating disease that seriously threatens yield worldwide. Utilization of host resistance is considered an effective strategy to minimize powdery mildew damage. , , and confer broad-spectrum resistance to wheat powdery mildew in China, of which and are allelic genes derived from the 6VS chromosome of , and is derived from the 6SS chromosome of and most likely orthologous to the former two genes. To accurately and efficiently transfer and pyramid these genes using marker-assisted selection (MAS), distinctive single-nucleotide polymorphisms (SNPs) among the exon sequences of , , and and their homologous sequences in the common wheat genome were identified and then used for developing diagnostic Kompetitive Allele-Specific PCR (KASP) markers. The markers were validated in different genotypes including transgenic vectors, transgenic lines, translocation lines, resistance stocks with documented genes, and in multiple susceptible cultivars without genes. As a result, we initially developed a KASP marker that can simultaneously diagnose , , and . Subsequently, we obtained a highly diagnostic KASP marker for each of the three genes that could distinguish among the three genes and also accurately distinguish them from other resistant stocks with documented genes and from multiple susceptible genotypes. Compared with previously reported markers, the highly diagnostic KASP markers developed in this study have the advantages of low cost, easy assay, accuracy, and potentially high throughput for MAS.