Characterization of PmDGM conferring powdery mildew resistance in Chinese wheat landrace Duanganmang.

Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a devastating disease threatening yield and quality. Host resistance is considered the most effective and preferred means to control this disease. Wheat landrace Duanganmang (DGM) showed high resistance or near immunity to Bgt mixture from Henan province, China. DGM was crossed with highly susceptible Chinese wheat landrace Huixianhong (HXH) and cultivar Shimai 15 (SM15) to produce genetic populations. The resistance of DGM to Bgt isolate E09 was shown to be controlled by a single dominant Mendelian factor, tentatively designated PmDGM. Marker analysis and 55K SNP (single nucleotide polymorphism) array scanning showed that this gene was positioned in the Pm5 interval (2.4 cM or 1.61 Mb) flanked by Xhenu099 and Xmp1158 in the Chinese Spring reference genome. Homology-based cloning and sequence analysis demonstrated that DGM has the identical NLR gene (Pm5e) and RXL gene reported in Fuzhuang 30 (FZ30) conferring and modifying the powdery mildew resistance, respectively. However, based on the different reaction patterns to the Bgt isolate B15 between DGM and FZ30, we speculate that DGM may have two tightly linked genes that could not be separated in the current mapping population, one is PmDGM and the other is Pm5e. Hence, this study provides a valuable resistance resource for improvement of powdery mildew resistance.