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United States Department of Agriculture

Agricultural Research Service

Research Project: Improved Control of Stripe Rust in Cereal Crops

Location: Wheat Genetics, Quality Physiology and Disease Research

Title: Comparative virulence and molecular diversity of stripe rust (Puccinia striiformis f. sp. tritici) collections from Pakistan and United States

Authors
item Bux, Hadi -
item Rasheed, Awais -
item Mangrio, Sher Muhammad -
item Abro, Saeed Akhtar -
item Ahmed Shah, Syed Jawad -
item Ashraf, Muhammad -
item Chen, Xianming

Submitted to: International Journal of Agriculture & Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 22, 2012
Publication Date: December 4, 2012
Citation: Bux, H., Rasheed, A., Mangrio, S., Abro, S., Ahmed Shah, S., Ashraf, M., Chen, X. 2012. Comparative virulence and molecular diversity of stripe rust (Puccinia striiformis f. sp. tritici) collections from Pakistan and United States. International Journal of Agriculture & Biotechnology. 14(6):851-860.

Interpretive Summary: Information on virulence and molecular diversity of the stripe rust pathogen is a pre-requisite for mitigating the substantial yield losses caused by stripe rust in Pakistan, the United States and other countries of the world. This study was undertaken to analyze both virulence and molecular diversity of 46 isolates of the stripe rust pathogen from Pakistan, in comparison with 9 US isolates. Avirulence to stripe rust resistance genes Yr5, Yr15 and YrSP was common among all tested isolates. Isolates from Pakistan had low virulence frequencies for wheat differentials carrying resistance genes Yr2; Yr10 and YrMor; and Yr2, Yr4a and YrYam. Clustering based on virulence data grouped the isolates together and revealed high genetic diversity among pathotypes of both countries. Molecular analysis using sequence tagged site (STS) and microsatellite (SSR) markers revealed high diversity based on polymorphic information contents and marker index which was higher for SSRs than STS markers. Dendrogram based on molecular marker data grouped together contemporary pathotypes indicating genetic similarity. Pathotypes belonging to both countries clustered together indicating common ancestry. Furthermore, very low correlation was observed between virulence and molecular diversity showing independence in both trends of diversity. The depicted virulence pattern of the isolates will guide in devising cultivar improvement efforts for stripe rust resistance.

Technical Abstract: Information on virulence and molecular diversity of Puccinia striiformis f. sp. tritici (Pst) is a pre-requisite for mitigating the substantial yield losses caused by the stripe rust pathogen in Pakistan, the United States and other countries of the world. This study was undertaken to analyze both virulence and molecular diversity of 46 Pst isolates from Pakistan, in comparison with 9 US isolates. Avirulence to stripe rust resistance genes Yr5, Yr15 and YrSP was common among all tested isolates. Isolates from Pakistan had low virulence frequency for differentials carrying Yr2, (Yr10, YrMor) and (Yr2, Yr4a, YrYam). Clustering based on virulence data grouped contemporary isolates together and revealed high genetic diversity among pathotypes of both countries. Molecular analysis using sequence tagged site (STS) and microsatellites markers revealed high diversity based on polymorphic information contents (PIC)and marker index (MI) which was higher for SSRs (0.78 & 39.51, respectively) than STS markers(0.04 & 0.29, respectively). Dendrogram based on molecular marker data grouped together contemporary pathotypes indicating genetic similarity. Pathotypes belonging to both countries clustered together indicating common ancestry. Furthermore, very low correlation (r=0.08) was observed between virulence and molecular diversity showing independence in both trends of diversity. The depicted virulence pattern of Pst isolates will guide in devising cultivar improvement efforts for stripe rust resistance.

Last Modified: 9/20/2014
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