Characterization of the Powdery Mildew Resistance Gene in Wheat Breeding Line KN0816 and Its Evaluation in Marker-Assisted Selection.

Wheat powdery mildew, caused by (DC.) Speer f. sp. is a destructive disease seriously threatening yield and quality of common wheat ( L., 2n=6x=42, AABBDD). Characterization of resistance genes against powdery mildew is useful in parental selection and for developing disease-resistant cultivars. Chinese wheat breeding line KN0816 has superior agronomic performance and resistance to powdery mildew at all growth stages. Genetic analysis using populations of KN0816 crossed with different susceptible parents indicated that a single dominant gene, tentatively designated , conferred seedling resistance to different f. sp. isolates. Using a bulked segregant analysis, was mapped to the interval on chromosome arm 2BL using polymorphic markers linked to the cataloged genes , , and , and flanked by the markers CISSR02g-6 and CIT02g-2, both with genetic distances of 0.7 cM. Analysis of closely linked molecular markers indicated that the marker alleles of differed from those of other powdery mildew resistance genes on 2BL, including , , , , and . Based on the genetic and physical locations and response pattern to different f. sp. isolates, is most likely a new powdery mildew resistance gene and possesses effective resistance to all the 14 tested f. sp. isolates. In view of the elite agronomic performance of KN0816 combined with the resistance, is expected to become a valuable resistance gene in wheat breeding. To transfer to different genetic backgrounds using marker-assisted selection (MAS), closely linked markers of were evaluated, and four of them (, , , and ) were confirmed to be applicable for MAS in different genetic backgrounds.