Genetic Analysis And Molecular Mapping Of A New Gene For Powdery Mildew In Wheat(Triticum Aestivum L.)

Powdery mildew caused by Blumeria graminis f.sp.Tritici is a one of the most destructive diseases of wheat (Triticum aestivum) in the world, and to develop and apply resistance cultivars is an environmental safe and effective way to control the disease. The related species of wheat is an important resource of wheat powdery mildrew resistance genes, and exploring new sorces of resistance genes in the relative of wheat is a most effective approach to the genetic improvement.The subjects of this study are the resistant material L962and the susceptible material L983, which are derived from the cross of YU25and MY11, and the wheat line YU25is immune to powdery mildew. Genetic analysis of the F1, F2, F2:3populations from the resistant lines L962and linkage ananlysis of the resistance gene by the method of wheat SSR markers.The main results as following:1.Respectively the resistant material L962as a female or the susceptible L983as a female parent,we found the all F1plants of L962×L983and the L983×L962were high resistant to powdery mildew after inoculation,which showed that the resistance of L962was dominant. Chi-square test results of the F2population implied that the ratio of resistance to susceptible was3:1at p=0.01level, and the homozygous resistant families, heterozygous resistance and homozygous susceptible were fit1:2:1. Therefore, the resistance to powdery mildew of L962was controlled by one dominant gene which was temporarily designated as PmL962.2. All the SSR markers whose average distance is5cM,which covering the whole wheat chromosomes can amplified the distinctive patterns, so we conclude the PmL962was not likely carried large transferred chromosome segments of the alien genes.3.Of the exceeding500pairs SSR primers,there were4pairs with polymorphism to be linked to PmL962. Then we designed SSR markers via the bioinformations and the Chinese Spring chromosome genes draft,there were4pairs with polymorphism to be linked to PmL962.These markers were associated with PmL962in an order of Xmag3930-2, Xwmc661B, Xgwm210, Xwmc314, PmL962, Xwmc154, Xgwml48, Xgwm410A, Xgpw1148-4and the relative genetic distance were7.085cM,1.470cM,2.499cM,7.772cM,17.332cM,29.737cM,2.486cM,2.829cM.4.By the analyse of the amplified patterns of the linked markers with PmL962on Chinese Spring nullisomic-tetrasomics,all the eight linked SSR markers amplified the expected band in the CN2AT2B, N2AT2D, N2DT2AandN2DT2B,but not in the N2BT2A,N2BT2D.The eight SSR markers are all located on2B chromosome.5. Comparing the resistance source and the responses of Bgt isolates, we think it maybe a new resistance powdery mildew gene which is different from Pm26and Pm42.