Preliminary Study On Evaluation And Utilization Of Resistance Genes Of Wuzhuamai With Immune To Wheat Powder Mildew

Wheat powder mildew is one of main factors resulted in decrease of wheat yield and inferior commercial quality of wheat grain. The situation of epidemic areas and disease severity of wheat powder mildew increasing continuously urges more resistance genes to be identified and utilized. In the study, the seedling and adult-plant resistances to wheat powder mildew and the inhibitory effect of crude toxin from Fusarium graminearium Schw to radicle growth were evaluated by using a recombinant inbred lines (RIL) population derived from cross of Wuzhuamai and Sumai3. The ISSR analysis was also performed and a new method called DMR-AFLP (DISEASERSIST Motif Restricted AFLP) was developed for improving the pertinence of screening molecular markers of target gene on the genome scale. Some STS primers were designed according to the sequences of cloned PCR fragments amplified by the DMR-AFLP and the STS analysis was performed. A new study scheme called TDMRAP (Two DISEASERSIST motifs restricted amplified polymorphism) was established and its effectivity was tested initially. The main results are as follows:1. The seedling and adult-plant resistances to wheat powder mildew were found firstly controlled by different genes. The two gene sites (SRPM and ARPM) were linked with a map distance of 13.7cM. 2. The inhibitory rate of crude toxin of F. graminearium Schw to radicle growth (called IRRT) showed that the Sumai3 (13.49%) had significantly greater ability of resistance to poison than Wuzhuamai (50.39%). The segregation of IRRT showed normal distribution. This indicated the IRRT was controlled by multigene family.3. Two Gene pyramiding lines, WSR005 and WSR032, were selected because their better ability of resistance to poison than Sumai3 and immunity to wheat powder mildew, no matter at seedling stage and adult stage. They also had fine comprehensive agronomic characters.4. Various ISSR primers had very different effects in PCR amplification. Two of the ISSR primers, GA8FS and AG8FS, generated clear and distinguishable band patterns with plentiful polymorphisms. But a single base difference at 3`-end of them resulted in the better specificity and sensitivity of AG6FS.5. DMR-AFLP method produced polymorphism bands between RP DNA pool of resistant plants and SP DNA pool of susceptible plants to wheat powder mildew. The result suggested that the method was effective in research of identifying resistance gene site. In the subsequent STS analysis, two STS sites, STSR6₅00 and STSR15₆00, were found linked to SRPM and ARPM with long linkage distances.6. No STS sites or ISSR sites were found on the interval from SRPM to ARPM. Three ISSR sites were found located at one side of the two resistance sites and two STS sites at another side. The nearest linkage distance of 9.7cM appeared between AG8-1800 and ARPM.7. Clear and distinguishable band patterns with plentiful polymorph- isms were produced in RIL population by TDMRAP method. This primary result laid a foundation for further evaluation of relativity between these polymorphism main bands and various disease resistances.