Molecular Identification of a Powdery Mildew Resistance Gene from Common Wheat Cultivar Brock

Abstract

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most important diseases of common wheat (Triticum aestivum L.) worldwide. Common wheat cultivar Brock introduced from UK is highly resistant (IT: 0;) to powdery mildew prevalent isolate E09 at the seedling and adult plant stages in North China. Genetic analysis using an F2 segregating population and F2:3 lines, derived from a cross between susceptible common wheat lines Xuezao and resistant common wheat line 3B529 (Jing 411*7//Nongda 015/Brock, F6), indicated that a single dominant gene, temporarily designated MlBrock, was responsible for the resistance of 3B529. By bulked segregant and molecular marker analyses, three polymorphic SSR markers (Xcfd81, Xcfd78, and Xgwm159) and two SCAR markers (SCAR203 and SCAR112) were found to be linked to MlBrock. Among these markers, Xcfd81 and SCAR203 were cosegregated with MlBrock, and SCAR112, Xcfd78, and Xgwm159 were linked to MlBrock with genetic distances of 0.5, 5.5, and 12.7 cM, respectively. According to the available physical bin mapping result of MlBrock cosegregated SSR marker Xcfd81 and SCAR203 in Chinese Spring, MlBrock was further located on chromosome bin 0–0.63 of 5DS. According to the infection-type of E09 Bgt isolate and mapping results, MlBrock might be powdery mildew resistance gene Pm2. The molecular markers developed in this study are useful for marker-assisted selection (MAS) and gene pyramiding of powdery mildew resistance genes in wheat breeding programs.