| Powdery mildew caused by Blumeria graminis f.sp.tritici is one of the most important wheat (Triticum aestivum L.em Thell) diseases worldwide. In recent years,the damage of the wheat powdery mildew has become more and more serious in many wheat regions of our country and it made severely damage in wheat production.Though chemistry controlling is useful, breeding for resistance has proved to be the most economical,effective and environmentally safe method to control the disease. Wild relatives of wheat have a large of resistance resources and they are a rich gene source for powdery mildew resistance, Haynalidia villosa is a wild relative of wheat, it is a good resistance resource to wheat diseases, and its 6V chromosome have immune resistance gene to powdery mildew.Up to now, more than 30 genes loci for resistance to powdery mildew have been identified.Among these genes, the Pm21(6AL/6VS), originating from Haynalidia villosa is one of the most effective resistance genes.Molecular marker technology is an effective measure for the identification and combinations of the resistance genes and it has been widely used to marker-assisted selection and gene pyramiding in wheat resistance breeding. In this study, SSR analysis combined with BSA was carried out in common wheat (AABBDD) N95175. The objectives of this study were to search new SSR markers tightly linked to this powdery mildew resistance gene. According to the location of SSR markers and using Chinese Spring nullisomic-tetrasomic and ditelosomic lines, the powdery mildew resistance gene was assigned to chromosome arms.F1 and F2 populations from crosses between N95175 and Abbondanza nullisomic (monosomic) lines were identified for resistance to powdery in the seedling stage. It found that the F1 generation of Abb/N9628-2 was all resistant to powdery mildew. The result of theχ2 test showed that the ratio of resistance plants and susceptible plants in F2 generation of Abbondanza 6AN×N95175 showed a clear deviation from 3:1, which indicated that the resistance of N95175 was controlled by a dominant gene on 6A. N95175 was a new wheat germplasm improved from wheat–Haynalidia villosa 92R149, that F1 of N95175×Shaan160 and N95175×Shaanyou225 were highly resistant to powdery mildew. The ratios of resistance plants and susceptible plants in F2 generation were 115:43 and 111:48, respectively. The segregation ratio fitted expected 3:1 so it suggested that powdery mildew resistance of N95175 was controlled by a dominant gene.Ten of 160 DNA samples extracted from the F2 population were pooled into two separate groups for bulked segregant analysis (BSA).By SSR analysis with 208 pairs of primers, two markers Xgwm570 and Xwmc553 generated polymorphic DNA fragments between the resistant and susceptible plants DNA pools. By analyzing the polymorphic markers in these segregating populations, Xgwm570 and Xwmc553 were linked to the resistance gene with genetic distance of 13.38cM and 12.03cM. Furthermore, the powdery mildew resistance gene in N95175 was physically mapped on chromosome 6AS using Chinese Spring nullisomic-tetrasomic and ditelisomic lines.Subunit compositions of the materials were analysed by the use of SDS-PAGE technique. The result showed that only one subunit of Haynalidia villosa was displayed, between the seven and eight subunit. After the improvement of the wheat germplasm N95175, the synthesis agronomic characters of N95175 are superior to its parents. |
