Virulence Structure And Genetic Diversity Of Blumeria Graminis F.sp. Tritici And The Resistance Screening From Wheat Varieties In Northeastern Spring Wheat Region

Powdery mildew of wheat, caused by Blumeria graminis f. sp. tritici, is one of the most serious diseases which have a strong impact on the safety production of wheat. Planting disease-resistant varieties is one of the most cost-effective ways to control the disease. The B. graminis f. sp. tritici can’t overwinter in northeast China because of it’s cold temperature, so the primary inoculum source might be from the southern region with the warm climate. This study was aiming to reveal the phylogenetic relationships of Wheat Powdery Mildew in Northeast China and Sichuan region. The single-gene differential hosts were used to identify the virulence dynamic of the wheat powdery mildew strains collected from Liaoning, Heilongjiang and Sichuan province. EST-SSR molecular technology was used to inquire the genetic diversity of wheat powdery mildew from different regions through clustering analysis method, to reveal the virulence diversity and to explore the genetic exchange between the two regions through aboved methods. Furthermore, in order to screen the resistant materials to wheat powdery mildew, the exotic germplasms and northeast China’s wheat cultivars or lines were evaluated at seedling and adult plant stages. The results are as it follows:1. Analysis on the virulence frequency of wheat powdery mildewThirty six single-gene differential hosts were used to analyze the virulence frequency of wheat powdery mildew sample collected from Liaoning, Heilongjiang and Sichuan province, which contained 80 single spore strains by separation and purification. The results was showed that the occurrence frequency of V21 (virulence gene,the same below) and VXBD were below 32％ in northeast China, indicating that Pm21 and PmXBD were effective and had a good resistance to the current popular strains. However, there was only one effective resistance gene, Pm21, in Sichuan Province.2. Genetic diversity analysis of wheat powdery mildewTwo pairs primers showing obvious polymorphisms were screened out from seven pair reported EST-SSR primers. The genetic diversity of 67 wheat powdery mildew samples collected from Liaoning, Heilongjiang and Sichuan province was analyzed through EST-SSR molecular marker technology. The virulence diversity of 36 strains isolated from the samples, collected in aboved regions, was also analyzed. The Clustering analysis showed that there was a certain genetic exchange among the B. graminis f. sp. tritici isolates from aboved regions. There was some correlation between the polymorphism and virulence diversity of B.graminis f. sp. tritici according to the comparison result, but no pronounced relationship was found.3. Resistance appraisal of powdery mildew of wheat cultivarsA total of 190 germplasms and 93 cultivars or lines were tested for resistance with mixture strains at both seedling and adult stages. The result showed that 11 wheat items from 190 germplasms were resistant to the tested strains at adult stage, accounted for 5.8%, but there was no seedling resistance found. Similarly there also no seedling or adult plant resistance found from 93 cultivars or lines to the tested strains. It was indicated that the wheat cultivars and germaplasms have poor resistance to wheat powdery mildew in northeast China, and it is particularly important to develop new disease resistant varieties.