Virulence And Genetic Polymorphism Of Puccinia Striiformis F. Sp. Tritici In Gansu, Qinghai, Xinjiang And Tibet Provinces

Wheat stripe rust, caused by Puccinia striiformis f. sp. Tritici (Pst), is one of the most destructive diseases of wheat worldwide. Wheat stripe rust is important fungal plant pathogen that can be disseminated thousands of kilometers across continents and oceans by wind. The most destructive epidemics of stripe rust has occurred many times in China and brought seriously yield loss. Gansu, Qinghai, Xinjiang, Tibet are located in Northwest and Southwest China and these four provinces are adjacent, the stripe rust occurred in Gansu and Qinghai province frequently and the pathogens evolved rapidly by compared to the other wheat growing regions, Xinjiang and Tibet belong to a relatively independent region, but because of their unique geographical location whether the pathogens can communicate with other regions is still need to be studied. Therefore, understanding the virulence structure, molecular polymorphism and phylogenetic relationship of wheat stripe rust pathogens among these four provinces described above are very important for forecasting and improving prevention and control capabilities of the disease.Based on the gene-for-gene theory,40near iso-genic lines (NILs) differentials or known yellow rust resistance (Yr) gene lines were used pathotyping80isolates of Pst from Gansu、Qinghai、Xijiang and Tibet provinces.7primer pairs of simple sequence repeat (SSR) markers were selected for molecular polymorphism and phylogeny of80stripe rust isolates from these four provinces. The results showed that, the virulence to Yr24and Yr26of all pathogens have not been found, and the virulence frequency of Yr10and Yr10+YrMoro was6.3%and5%, respectively. The other Yr genes all showed high virulence except for few samples from Xinjiang and Tibet which showed a virulence frequency of0. The virulence pattern of the80isolates was tested and virulence structure was analyzed by cluster analysis using NTSYSpc2.2. The results showed that the virulence existed higher similarity among the isolates, and the similarity coefficient was ranged from0.58to0.95. Among the four provinces, the stripe rust pathogens from Gansu possess the widest virulence spectrum, Qinghai ranked after it, Xinjiang and Tibet also possessed wide virulence spectrum but both of them have their own features.7pairs of SSR primer were selected for genetic diversity analysis, a total of11 polymorphic bands were detected, the data was analyzed by cluster analysis using NTSYSpc2.2. The clustered results showed that the similarity coefficient of SSR was ranged from0.48to1.00, which indicating that distinct polymorphism was found among stripe rust pathogens from the four provinces. Comparative analysis of the stripe rust pathogens from Gansu and Qianghai suggested substantial exchanges were existed, the samples from Xijiang and Tibet are relatively independent. The tested isolates showed a very low association between the virulence frequency polymorphisms and DNA polymorphisms and SSR, and the similarity coefficient was0.04748.