Identification of a Novel Powdery Mildew Resistance Gene in a Winter Wheat Cultivar

Wheat (Triticum aestivum) is an important staple crop that sustains over one-third of the global population. Powdery mildew, an economically important disease caused by Blumeria graminis f. sp. tritici (Bgt), significantly affects wheat production in many wheat-growing regions. Therefore, identification of novel powdery mildew resistance genes that can be easily used in wheat cultivar development is essential for meeting the needs of the increasing global human population. PI 606247 (formerly 'Samara') is a winter wheat cultivar developed in the Czech Republic in 1995 that exhibits resistance to representative U.S. Bgt isolates. An F₇ recombinant inbred line (RIL) population derived from PI 606247 × Jagalene was evaluated for responses to Bgt isolate OKS(14)-B-3-1. Genetic analysis indicated that a single gene, designated PmSA, conditions powdery mildew resistance in PI 606247. Selective genotyping of a subset of RILs identified a set of single nucleotide polymorphisms (SNPs) co-segregating with powdery mildew resistance in the terminal region of chromosome arm 2BL. Linkage analysis using Kompetitive Allele Specific PCR (KASP) markers located PmSA to a 14.43-Mb interval between 686.69 and 701.12 Mb in the Chinese Spring IWGSC RefSeq v2.1 reference sequence. PmSA is a new powdery mildew resistance gene differing from the others in the terminal region of 2BL in genomic location, origin, and responses to a set of Bgt differential isolates. PmSA is valuable for enhancing powdery mildew resistance, and the KASP markers closely linked to PmSA can facilitate its rapid deployment in wheat cultivars via marker-assisted selection.