Identification and mapping of two new genes conferring resistance to powdery mildew from Aegilops tauschii (Coss.) Schmal

Two powdery mildew resistance genes were identified from Aegilops tauschii accessions Y201 and Y212 and mapped using two different F-2 populations derived from the crosses between susceptible accession Y2272 and Y201, and susceptible accession Y2263 and Y212. Genetic analysis of resistance to powdery mildew indicated that the resistance of Y201 was controlled by a single dominant gene, whereas the resistance of Y212 was controlled by a single recessive gene. We have temporarily designated these genes as PmY201 and PmY212, respectively. By bulk segregation analysis, six microsatellite markers including Xgwm174, cfd26, cfd57, cfd102, Xgwm583 and Xgwm639 were found to be linked to PmY201 with genetic distances of 5.2, 7.7, 9.6, 12.5, 20.2 and 22.1 cM, respectively. Five SSR markers, including cfd57, Xgwm182, cfd7, cfd102, and cfd12, were found to be linked to PmY212 with distances of 5.6, 7.2, 11.5, 14.7, and 18.5 cM, respectively. According to the locations of the linked markers, the two resistance genes were located in the 5DL region. Based on the chromosomal locations and the resistance patterns of the two genes, we propose that PmY201 and PmY212 are two novel powdery mildew resistance genes, and are suitable for marker-assisted selection.