ARS | Publication request: IDENTIFICATION AND VALIDATION OF MOLECULAR MARKERS FOR THE STEM RUST RESISTANCE GENE SR36 ON CHROMOSOME 2BS IN WHEAT

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: October 13, 2007
Publication Date: January 1, 2007
Citation: Tsilo, T.J., Jin, Y., Anderson, J.A. 2007. Identification and validation of molecular markers for the stem rust resistance gene sr36 on chromosome 2bs in wheat [abstract]. Plant and Animal Genome Conference. P137:SSR.

Technical Abstract: Puccinia graminis f. sp. tritici, the causal agent of wheat stem rust, has emerged as a serious threat in Eastern Africa where a new race (TTKS, or commonly known as Ug99) has been reported. This new race poses a serious threat to wheat production worldwide. The stem rust resistance gene Sr36, derived from T. timopheevii, confers resistance to TTKS and to many other races of stem rust. However, breeding for durable resistance requires pyramiding of Sr36 with other genes into a single genotype, a process that can be facilitated through the use of molecular markers. The aim of this study was to identify microsatellite (SSR) markers for the detection of the Sr36 gene in breeding programs. Two mapping populations of 122 F2 (LMPG x Sr36/9*LMPG) and 112 F2 (Chinese Spring x W2691Sr36-1) exhibited distorted segregation with a preferential transmission of the Sr36-carrying segment. Partial genetic linkage maps were constructed using co-dominant SSR markers. Two markers, Xstm773-2 (Bariana et al., 2001) and Xwmc477, flanked Sr36 at a genetic distance of 0.4 cM, and Xgwm319 was in complete linkage with Sr36 in the LMPG population. In the Chinese Spring population, Xstm773-2 and Xwmc477 were in complete linkage with Sr36, while Xgwm319 was 0.9 cM away. These markers were easy to score and were diagnostic for Sr36 in a diverse set of 76 wheat cultivars and breeding lines developed in 12 countries. Together, these markers can be used in marker-assisted selection of Sr36, and also as the first step toward cloning of Sr36.