Abstract: Powdery mildew is one of the most serious wheat diseases in China. Identification of slow mildewing resistance genes and their closely linked molecular markers is very important for developing wheat cultivars with durable resistance. An F2:3 population with 218 lines derived from the cross between Bainong 64 and Jingshuang 16 were sown with three replicates in Beijing and Anyang, Henan Province. Inoculation was carried out with the isolate E20 of B. graminis f. sp. tritici before stem elongation, and disease severity to powdery mildew was scored for 4 times until the leaves were physiologically mature in Beijing during 2003-04 and 2004-05 cropping seasons. In Anyang, disease was evaluated around May 18, in 2004-05 cropping season under natural inoculation. A total of 100 SSR markers and 58 AFLP markers were used to construct a linkage map, covering 3114 cM of wheat linkage groups except chromosome 1D. With the method of composite interval mapping (CIM), three QTLs were found on chromosomes 2B, 2D and 4D, in which the QTLs on chromosomes 2B and 2D were detected across two environments, accounting for 9.6%~11.3% and 21.2%~26.1% of phenotypic variance, respectively. The QTLs showed additive and partially dominant effect and the additive effects were derived from the resistant parent Bainong 64. The molecular markers identified in this study will certainly benefit for marker-assisted selection and pyramiding of resistance genes to powdery mildew in wheat breeding programs.

Key words: Bread wheat (Triticum aestivum L.), Powdery mildew, Slow mildewing resistance, QTL mapping