Virulent Race Overcome Wheat Stem Rust Resistance Gene Sr27 in Egypt

Document Type : Original Article

Author

Wheat Dis. Res. Dept., Plant Pathol. Res. Inst., ARC, Giza, Egypt.

Abstract

Triticale is an excellent source of resistance to wheat stem rust, caused by Puccinia graminis f.sp. tritici. Stem rust historically is one of the most destructive diseases of wheat (Triticum aestivum L.) worldwide. Deployment of resistant genotypes successfully prevented rust epidemics over the past several decades. This is primarily due to the on-going incorporation of effective stem rust resistance genes into new wheat breeding materials; this may place the pathogen under great selection pressure. Although Sr27 has little effect on the commercial wheat production, it has a major impact on the commercial triticale cultivars. In Egypt, high levels of stem rust infection were observed on wheat cultivar (Cooring) which carrying Sr27 grown at Gemmiza Research Station during May 2015. Samples collected from rusted stems of wheat cultivar (Cooring) were cut and artificially inoculated on primary leaves of 8-day-old seedlings of highly susceptible wheat Cv. Morocco. Four single pustules were collected and race analysis was done. Results showed that out of the  four identified races, race QQQCM was the most virulent one wheat seedling carrying Sr27 with infection type (4), whereas the rest of races were a virulent to Sr27. This race (QQQCM) first time toappear in Egypt from previous identified races. Regarding to the performance of 20 stem rust resistant genes at seedling stage, (Sr 9e,7b,8a,9g,30,17,9a,9d,10,31and Sr38) were resistant to race QQQCM, meanwhile the rest Srs were susceptible 

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