Location: Hard Winter Wheat Genetics Research Unit
Title: Molecular Mapping of Stem Rust Resistance Gene Sr40 in Wheat Authors
|Wu, Shuangye -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 4, 2009
Publication Date: September 1, 2009
Citation: Wu, S., Pumphrey, M.O., Bai, G. 2009. Molecular Mapping of Stem Rust Resistance Gene Sr40 in Wheat. Crop Science. 49:1681-1686. Interpretive Summary: Stem rust was historically one of the most destructive diseases of wheat worldwide. Extensive use of resistant cultivars successfully prevented rust damage over the past several decades. Recently, a new race of the stem rust pathogen called Ug99 has appeared in Africa and has defeated many existing resistance genes. Stem rust resistance gene Sr40 has been transferred from the wild wheat Triticum timopheevii ssp. Armeniacum and provides resistance against Ug99 stem rust. In this study, we identified several molecular markers for Sr40 that will be useful in marker-assisted selection for resistance.
Technical Abstract: Stem rust, caused by Puccinia graminis f. sp. tritici, was historically one of the most destructive diseases of wheat worldwide. Deployment of resistant cultivars successfully prevented rust epidemics over the past several decades. Unfortunately, race TTKS (termed Ug99) has emerged in Africa to render several stem rust resistance genes ineffective. Sr40, a stem rust resistance gene from Triticum timopheevii ssp. armeniacum, was transferred to wheat on translocation chromosome T2BL/2G#2S and provides effective levels of seedling and adult plant resistance against Ug99. Two mapping populations were developed using Ug99-resistant line ‘RL6088’ and moderately susceptible to susceptible hard winter wheat cultivars ‘Lakin’ and ‘2174’. The parents were screened with 83 simple sequence repeats (SSR) from chromosome 2B and the polymorphic markers were analyzed on F2 populations. F2 and F2:3 populations were inoculated with North American stem rust race RKQQ at the seedling stage. Marker locus Xwmc344 was most closely linked to Sr40 (0.7 cM) in the RL6088/Lakin linkage map, followed by Xwmc474 and Xgwm374. Marker locus Xwmc474 was mapped ~2.5 cM proximal to Sr40 in the RL6088/2174 population. Xwmc474 and Xwmc661 flanked Sr40 in both populations. Markers linked to Sr40 will be useful for marker-assisted integration and pyramiding of Sr40 into elite wheat breeding lines, and reduction in the size of the T. timopheevii segment harboring this gene.