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Title: Genotyping U.S. wheat germplasn for presence of stem rust resistance genes Sr2, Sr24, Sr26, Sr36 and Sr1RS-Am

item Marshall, David
item Brown-Guedira, Gina

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/20/2007
Publication Date: 12/20/2007
Citation: Olson, E., Marshall, D.S., Brown Guedira, G.L. 2007. Genotyping U.S. wheat germplasn for presence of stem rust resistance genes Sr2, Sr24, Sr26, Sr36 and Sr1RS-Am. Meeting Abstract.

Interpretive Summary: N/A

Technical Abstract: Wheat germplasm from throughout the U.S. was surveyed for the stem rust resistance genes Sr2, Sr24, Sr26, Sr36 and the 1AL.1RS rye translocation that have conferred resistance to race TTKS of Puccinia graminis f.sp. tritici identified in Uganda and Kenya. A collection of 804 cultivars and breeding lines of wheat (Triticum aestivum L.) and 12 lines of durum wheat (Triticum turgidum L.) from all growing regions of the United States were screened with simple sequence repeat (SSR) and sequence tag site (STS) markers linked to stem rust resistance genes to determined frequencies of these genes U.S. wheat germplasm. None of the U.S. lines surveyed possess the Thinopyrum ponticum–derived gene Sr26. In general, the marker analysis revealed less resistance in the spring wheat germplasm than in U.S. winter wheats. The Sr24/Lr24 translocation is present in 11% of lines tested and is most frequent in hard winter wheat lines from the Great Plains. The 1AL:1RS translocation that confers resistance to TTKS was present in 7% of the winter wheat lines surveyed and was not present in any spring wheat germplasm. Eastern soft winter wheat germplasm has been the primary source of Sr36. The SSR marker Xgwm533 was not predictive of the presence of Sr2 and new markers are being tested to screen for this gene. For 413 lines, phenotypic data from evaluation of seedlings with stem rust was used to validate the genotypic data. In general, the molecular marker data was consistent with phenotypic observations. Identification of the principle sources of stem rust resistance genes in U.S. germplasm effective against the TTKS race of stem rust will aide in the development of more diverse and durable resistance profiles.