A Genetic Linkage Map Of Blumeria Graminis F.sp.tritici Based On AFLP Molecular Markers And Avirulence Genes

Wheat is the second largest food crop in China. Powdery mildew (Blumeria graminis f.sp. tritici) is one of the most serious diseases in wheat. So the research on this disease is very important. It is limited in the research of wheat powdery mildew genetics in China and there is no report on the clone of avirulence genes or other functional genes. Although a linkage map of wheat powdery mildew has been constructed by Li Zhiying (2004), the linkage map is still quite incomplete with limited number of markers, and there are no markers that are linked closely to avirulence genes or other functional genes.There is no other report on the linkage map of wheat powdery mildew so forth and the chromosome number has not been finally determined. The construction of linkage map is the fundamental of the fungal genomics and genetic research.The linkage analysis was conducted on 97 segregating haploid progeny isolates from a cross between 2 isolates, E17 and CPW-1, differing in eight avirulence genes. The amplified fragment length polymorphism (AFLP) technique was used to analyze the polymorphism of parent and progeny isolates. MAPMAKER/EXP (3.0b) and mapping software MapDraw V2.1 were used to construct the linkage map.102 pairs of AFLP primers were used to analyze the polymorphism of parent isolates and 61 pairs showed polymorphism. 144 data was obtained including 6 avirulence data in total. A total of 117 loci were mapped, comprising 112 AFLP markers and 5 avirulunce genes. The markers are distributed over 10 linkage groups covering a total of 1425.1 cM and the distance of two loci is about 12.2 cM in average. The 5 avirulence loci are distributed in four linkage groups. Among them, avirulence genes Avr4b and Avr4a are clustered tightly in Bgt1 and linked to markers P11M23.3 and P18M15.1 with the estimated genetic distance of 4.2 cM and 4.5 cM. Avr13 locates between markers P22M18.1 and P13M17 in Bgt1 with the genetic distance of 0.6 cM and 0.1 cM, respectively. Avr3c and P20M11 are linked and the genetic distance is 3.0 cM in Bgt2. Avr3f was targeted in Bgt8.This is a much more complete genetic linkage map of wheat powdery mildew, compared with the existing ones with 117 loci and the AFLP molecular markers that are closely linked to a few avirulence genes are reported for the first time. This laid the foundation for the cloning of avirulence genes and provided the basis of genetic and functional genomic researches for the powdery mildew pathogen in wheat.