Mapping Of A Wheat Powdery Mildew Resistance Gene In Chinese Landrace Xiaohongpi

Powdery mildew caused by Blumeria graminis f. sp. tritici is an severe foliar disease of wheat in worldwide. Landrace had undergone natural and manual selections for a long time and had abundant genetic variations. Therefore, landraces contain many useful genes such as powdery mildew resistance genes and thus an important resource for wheat improvement. Chinese wheat landrace Xiaohongpi is highly resistant to powdery mildew at seedling stage. Classical genetic analysis indicated that Xiaohongpi contains two recessive powdery mildew resistance genes, but molecular mapping showed that Xiaohongpi had only one recessive resistance gene. This gene linked with Xgwm311, Xgwm382, Xhbg327 and Xgwm356, and co-segregated with two STS markers Xp9-7 and Xsts_bcd1231. According to the linked microsatellite markers'location confirmed by Chinese Spring deletion lines, the resistance gene was localizated on 2AL. Allelism test and powdery mildew resistance spectrum analysis confirmed that this recessive resistance gene was a new allele of Pm4.