The Population Genetic Structure Of Blumeria Graminis F.Sp.Tritici In Southwest Of Sichuan And The Impacts Of Intercropping On Epidemic Of Wheat Powdery Mildew

Samples of Blumeria graminis f.sp.tritici were collected from six cities to reveal the genetic structure of the fungus in southwest Sichuan. Traditional methods of virulence frequence and modern molecular markers technique were used to test the genetic diversity of48powdery mildew strains in this study.The test also explored the control efficiency of intercropping on the occurrence of powdery mildew and its influence on wheat grain quality and yield.The virulence frequence of forty-two powdery mildew strains were studied by thirty varieties which contain different resistance genes to wheat powdery mildew. The result showed that the structure of Blumeria graminis f.sp. tritici population in southwest Sichuan was relatively complex and had highly pathogenic. V6, V3a, V19, V3b, Vlshowed virulence frequency reached more than70%, which mean the wheat who contained disease-resistant genes of Pm6, Pm3a, Pm19, Pm3b, Pmlhad lost its resistance and were not suitable for growing on a large scale; while virulence frequency ofV5+6, Vera, V5(mli), V21, V2+6, V13, VXBD were in a low level, which mean the wheat who contained Pm5+6, PmEra, Pm5(mli), Pm21, Pm2+6, Pm13and PmXBD still have better resistance. Especially the varieties of Era, Aquila, Yangmai5/Sub.6v, Maris huntsman, R4A and xiaobaidongmaiXBD can still play an important role in disease resistance breeding of wheat.The genetic diversity of48powdery mildew strains was analyzed by SRAP molecular markers, the result showed that:10primers were selected and160loci were abtained though amplification. It mainly focused on100～2000bp.50.63%with81polymorphic loci were polymorphic frequence which showed powdery mildew in southwest of Sichuan province were abundance in genetic polymorphism. Clustering analysis showed that stains from different places can cluster together. And we can learn that stains collected from same regions had closer relationship significantly. From the perspective of genetic distance,48powdery mildew strains were test with genetic distance from0.0382-0.5108, and the diversity of them were rather obvious. By comparing virulence diversity and genetic diversity analysis of clustering relationship, there do not exist one-to-one corresponding relationship.In order to explore the impacts of intercropping on Epidemic, we set several different plant pattern in Ya’an and Jianyang.It can be seen from the result that intercropping obviously reduced the occurrence of wheat powdery mildew, increased the content of protein and the yield of wheat. The results in2011and2012demonstrated that the wheat theoretical yield and thousand seed weight in intercropping system were significantly higher than those in wheat monocropping system in Ya’an district. Thousand seed weight of Intercropping improved over10%than wheat monocropping, and the theoretical yield in the intercropping system increased about25%, whereas the experimental results in2012in Jianyang showed that the thousand seed weigh and the theoretical yield of wheat monocropping were all lower than wheat intercropping.