The Identification And Mapping Of A Novel Resistance Gene To Powdery Mildew In Wheat With Molecular Markers

Powdery mildew is a major fungal disease on wheat(Triticum aestivum L.) caused by Blumeria graminis f.sp.tritici.The use of resistant cultivars is the most economical and effective means to control this disease.The landraces of wheat contain abundant resistance genes to powdery mildew,which are promising resistant resources for breeding new resistant cultivars.The wheat landrace QZ180 shows excellent resistance to powdery mildew.Genetic analysis of resistance and linkage microsatellite markers of the gene for resistance to powdery mildew facilitates utilization of the resistance gene and is useful in marker-assisted selection(MAS).The main outcomes of this study are summaried as follows:1.The wheat landrace cultivar QZ180 was resistant to 9 of 14 isolates of B.graminis f.sp.tritici and had different infection patterns from those cultivars with known Pm genes. The resistance gene that QZ180 carries should be different from the known Pm genes.2.The two F₂ segrant populations and one F₃ family lines from a Beijing 837×QZ180 cross were inoculated with isolate E09 of B.graminis f.sp.tritici at seedling stage in greenhouse for resistant genetic analysis.The ratio of resistant to susceptible plants in F₂ population was 3:1,and the ratio of resistant,heterogeneous,and susuceptible families in the F₃ lines was 1:2:1.These results show that the resistance to wheat powdery mildew of QZ180 is controlled by a single dominant gene.The gene is temporarily designated PmQZ180.3.Microsatellite markers were used to analysis PmQZ180,three co-dominant microsatellite markers were linked to PmQZ180 and their most likely order was established as:PmQZ180-Xgwm382-Xgwm311-Xgwm356.The lingkage distances were 5.3 cM,14.0 cM,and 47.3 cM,respectively.The results were verified using F₃ lines.4.Gene PmQZ180 was mapped on the long arm of 2A chromosome.The lingkage distance of PmQZ180 differs from any other known resisitance genes on 2AL.It can thus be a novel resisitance gene.