Molecular characterization of a novel powdery mildew resistance gene Pm30 in wheat originating from wild emmer

Powdery mildew caused by Erysiphe graminis f. sp. tritici is one of the most important wheat diseases in many regions of the world. A powdery mildew resistance gene, originating from wild emmer wheat (Triticum dicoccoides) accession 'C20', from Rosh Pinna, Israel, was successfully transferred to hexaploid wheat through crossing and backcrossing. Genetic analysis indicated that a single dominant gene controls the powdery mildew resistance at the seedling stage. Segregating BC1F2 progenies of the cross 87-1/C20//2*8866 were used for bulked segregant analysis (BSA). The PCR approach was used to generate polymorphic DNA fragments between the resistant and susceptible DNA pools by use of 10-mer random primers., STS primers, and wheat microsatellite primers. Three markers, Xgwm159/430, Xgwm159/460, and Xgwm159/500, were found to be linked to the resistance gene. After evaluating the polymorphic markers in two segregating populations, the distance between the markers and the mildew resistance gene was estimated to be 5-6 cM. By means of Chinese Spring nullisomic-tetrasomics and ditelosomics, the polymorphic markers and the resistance gene were assigned to chromosome arm 5BS and were physically mapped on the gene rich regions of fragment length (FL) 0.41-0.43 by Chinese Spring deletion lines. As no powdery mildew resistance gene has been reported on chromosome arm 5BS, the mildew resistance gene originating from C20 should be a new gene and is designated Pm30.