Genetic Analysis And Molecular Mapping Of Yellow Dwarf Virus Powdery Mildew Resistance Gene And Resistance Gene In Wheat

Barley yellow dwarf virus, which was spreaded by aphids, can cause one of the most serious virus diseases of small-grain cereals, i.e, wheat, worldwide. There is no effective resistance gene in Triticum.Thinopyrum intermedium, a wheat relative, shows a high level of resistance to BYDV. It possesses Bdv2 resistance gene which locates on the long arm of 7Ai-1L chromosome of Th.intermedium, Bdv2 resistance gene has strong resistance and a wide rage resistance. In order to study BYDV resistance gene Bdv2 and fine mapping of this gene, The confrontation with selected mutant of yellow dwarf disease. For wheat functional genomics, in particular, BYDV resistance genes provide the basic material. Then use PCR markers with BYDV resistance genes analyze YW642 and some mutants.1. The wheat-Thinopyrum intermedium translocation line YW642 carries a T. intermedium-derived resistance gene to barley yellow dwarf virus, Bdv2. The wheat line YW642 was treated by EMS (ethyl methane sulfonate) for the construction of the mutant library. After the selection from M2 plants, 5 mutants with BYDV sensitivity were identified through verifications of M3 to M4 generations, whose resistances to BYDV infection were reduced to various extent, and could be inheritable.2. Molecular analysis indicated that the molecule basis of these BYDV sensitive mutants lost different PCR markers, suggesting that distinct sequence mutants occurred in the region with Bdv2 in these mutants.Powdery mildew is one of the most important devastating diseases of common wheat worldwide. Molecualr markers tightly linked to resistance genes not only facilitates the identification and mapping of resistance genes, but also can be used for marker-assisted selection(MAS).MAS greatly enhances the breeding efficiency and expedites the process. In the present study, we had constructed the genetic maps of PmHO, discussed the application of the tightly linked markers in target resistance gene, contribute to the further cloning of resistance genes, nurture and promote the resistant cultivars.1. An F2 population derived from a cross between ZHO and han4589 were analyzed for the resistance pattern in ZHO. Genetic analysis and chi-square test of phenotype of F2 population showed that the ratio of resistant and susceptible plants in F2 fitted the expected 3 to 1 ratio. The results indicated that powdery mildew resistance of ZHO at seeding stage was controlled by a single dominant gene, temporarily designated as PmHO.2. DNA samples extracted from leaves of the F2 population were extracted and ten each of resistant and susceptible individuals DNA were pooled into two separate groups for bulked segregant analysis(BSA).PCR amplification with 456 primer pairs were used to screen polymorphic markers. On the 3AS chromosome, SSR markers, five(Xmag912, Xbarc57, Xbarc12, Xmag905, Xwmc532) were shown to linked with the powdery mildewresistance gene in ZHO. Linkage analysis showed that these five markers have the estimated genetic distance of 3.1cM,3.9cM,4.5cM,8.0cM,9.0cM, respectively. Since no powdery mildew resistance genes were mapped on wheat 3AS chromosome, PmHO on 3AS may be a new one.