Locating And Molecular Mapping Stripe Rust Resistance Gene In New Common Wheat Germplasm Using SSR Markers

Puccinia striiformis is one of three main diseases of wheat. As yellow rust bacterium have stronger specilization and stripe rust races change frequently, resistant varities in wheat lose their resistance rapidly because of single resistant source after the varities are planted in large scale in the field. The practice showed that slecting and culturing varities of diseases resistance was the most economic, safety and effective method for preventing stripe rust. So searching for new resistant sources and resistant gene is a basis of molecular genetic study. This study constucted F2 seperated population from a cross of Huixianhong(susceptible)×Tike2(resistant) that is a new wheat germplasm with good agronomic characters and strong resistance to prevalent races of stripe rust. Then the phenotypes of Tike2 were evaluated by inculating CY31 germ and mapping the resistant gene by using the method of microsatellite markers and BSA. The results showed as follow:1. The study was conducted to elucidate the inheritance of resistance to stripe rust in the segregating population of F2 from a cross of Tike2(resistant)×Huixianhong (susceptible) by using the major gene plus polygene mixed inheritance model. The infected types of F2 population were evaluated in the field by inoculating Tiaozhong31 germ.The results indicated that the resistance regularity of F2 population to CY31 was controlled by a pair of major gene plus polygene. Major gene showed completely negative dominance, following genetic modelA-4. The inheritabilities of the major gene were about 79.63% and 85.67%,respectively. Meanwhile, the results also showed that the material included excellent resistant source to CY31, which could widen wheat resistant gene pool and offer new intermediate material for resistant breeding to stripe rust.2. Select wheat microsatellite primers among resistant and susceptible parents, resistant and susceptible bulk by using the method of microsatellite markers and BSA. From about 280 pairs of wheat microsatellite primers, there were about 52 pairs of primers that amplified polymorphic DNA fragments among resistant and susceptible parents. The Xgwm67 and Xgwm213 of 5B chromosome primers amplified characteristic bands relating with resistance among resistant and susceptible bulk. This seemed this primers corresponding microsatellite loci have linkage relationship with resistant gene.3. According to amplified polymorphic DNA fragments among 98 plants from F2 segregating population by Xgwm67 and Xgwm213, the segregating results of resistance and susceptance were similar with the investigative results in the field. Mapmarker EXP3.0b calculated that genetic distances between primers and resistant gene YrTi were 7.9cM and 15.1cM, respectively. The order among centromere, markers and gene was centromere---Xgwm67---Xgwm213---YrTi. We could deduce that the gene YrTi was located on 5BL chromosome and closed to centromere region. About if the resistant gene is a new gene, we also need validate it though allelism test further.The above results could offer theory evidence for genetic analysing, mapping of wheat resistant gene to stripe rust and molecular marker assisted selection.