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Title: Virulence and molecular comparison of Puccinia striiformis f. sp. tritici populations in China and the United States

Author
item ZHAN, GANGMING - Washington State University
item Chen, Xianming
item KANG, ZHENSHENG - Northwest Agriculture And Forestry University
item WANG, MEINAN - Washington State University
item WAN, ANMIN - Washington State University
item CHENG, PENG - Washington State University

Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2011
Publication Date: 7/1/2011
Citation: Zhan, G., Chen, X., Kang, Z., Wang, M., Wan, A., Cheng, P. 2011. Virulence and molecular comparison of Puccinia striiformis f. sp. tritici populations in China and the United States. American Phytopathological Society. 101:5201.

Interpretive Summary: Stripe rust is one of the most important diseases of wheat in both China and the U.S. The rust populations of these countries were compared for virulence patterns on wheat genotypes used to differentiate races of the pathogen and genotypes using molecular markers. From 86 Chinese isolates, 58 races were identified based on reactions on the 17 Chinese differentials and 52 races were identified based on the 20 U.S. differentials. The selected 51 U.S. isolates, representing 50 races based on the U.S. differentials, were identified as 42 races using the Chinese differentials. A total of 132 virulence patterns were identified from the 137 isolates based on their reactions on both Chinese and U.S. differentials. From the 137 isolates, molecular markers identified 102 genotypes, of which 71 from the Chinese isolates and 31 from the U.S. isolates. Virulence and SSR data had a low, but significant correlation. The Chinese and U.S. populations had similar levels of diversity. Principal analysis using the molecular marker data separated the two populations more clearly than using the virulence data. A non-rooted tree generated using the molecular data indicated that the Chinese and U.S. populations have evolved independently, but may share the same origin, which was also supported by the low value of differentiation and high value of gene flow. The findings are useful in understanding genetic evolution of the pathogen and provide information on virulence and avirulance to guide breeding wheat cultivars with effective stripe rust resistance.

Technical Abstract: Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat in both China and the U.S. The Pst populations of these countries were compared for virulence patterns on wheat genotypes used to differentiate races of the pathogen, and genotypes using simple sequence repeat (SSR) markers. From 86 Chinese isolates, 58 races were identified based on reactions on the 17 Chinese differentials and 52 races were identified based on the 20 U.S. differentials. The selected 51 U.S. isolates, representing 50 races based on the U.S. differentials, were identified as 42 races using the Chinese differentials. A total of 132 virulence patterns were identified from the 137 isolates based on their reactions on both Chinese and U.S. differentials. From the 137 isolates, SSR markers identified 102 genotypes, of which 71 from the Chinese isolates and 31 from the U.S. isolates. Virulence and SSR data had a low (r=0.38), but significant (P=0.01) correlation. The Chinese and U.S. populations had similar levels of diversity based on Kosman indices. Principal analysis using the SSR data separated the two populations more clearly than using the virulence data. A non-rooted tree generated using the molecular data indicated that the Chinese and U.S. populations have evolved independently, but may share the same origin, which was also supported by the low value (0.13) of differentiation and high value (1.74) of gene flow.