ARS | Publication request: DIAGNOSTIC MICROSATELLITE MARKERS FOR DETECTION OF STEM RUST RESISTANCE GENE SR36 IN DIVERSE GENETIC BACKGROUNDS OF WHEAT

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2007
Publication Date: January 1, 2008
Citation: Tsilo, T.J., Jin, Y., Anderson, J.A. 2008. Diagnostic microsatellite markers for detection of stem rust resistance gene Sr36 in diverse genetic backgrounds of wheat. Crop Science. 48:253-261.

Interpretive Summary: Stem rust of wheat is one of the most serious diseases of wheat worldwide. Host resistance is more effective and durable when several stem rust resistance (Sr) genes are pyramided into a single genotype, a process that can be facilitated by marker-assisted selection. The wheat stem rust resistance gene Sr36, derived from Triticum timopheevi, confers a high level of resistance against a new race (TTKS, or commonly known as Ug99) and many other races of the stem rust pathogen. Because Sr36-virulent races exist, breeding for durable resistance would require pyramiding of Sr36 with other genes, a process that can be facilitated by DNA markers. The aim of this study was to identify microsatellite markers for the detection of the Sr36 gene in wheat breeding programs. Segregating populations were used to identify molecular markers linked to the Sr36 gene. Three closely linked markers, Xstm773-2 and Xwmc477, flanked Sr36 at a genetic distance of 0.4 cM were identified, and Xgwm319 in complete linkage with Sr36 in one of the populations, were identified. These co-dominant markers were easy to score and diagnostic for Sr36 in a set of 76 wheat cultivars and breedling lines developed in 12 countries. Together, these markers can be used in marker-assisted selection of Sr36.

Technical Abstract: The wheat stem rust resistance gene Sr36, derived from Triticum timopheevi, confers a high level of resistance against a new race (TTKS, or commonly known as Ug99) and many other races of Puccinia graminis f. sp. tritici. Because Sr36-virulent races exist, breeding for durable resistance would require pyramiding of Sr36 with other genes, a process that can be facilitated by DNA markers. The aim of this study was to identify microsatellite markers for the detection of the Sr36 gene in wheat breeding programs. Two populations of 122 F2 (LMPG-6 X Sr36/9*LMPG) and 112 F2 (Chinese Spring X W2691Sr36-1) were evaluated for stem rust reaction. Both populations exhibited distorted segregation with a preferential transmission of the Sr36-carrying segment. Two markers, Xstm773-2 and Xwmc477, flanked Sr36 at a genetic distance of 0.4 cM, and Xgwm319 was in complete linkage with Sr36 in the LMPG-6 X Sr36/9*LMPG population. In the Chinese Spring X W2691Sr36-1 population, Xgwm319 was 0.9 cM away from Xstm773-2, Xwmc477 and Sr36. These co-dominant markers were easy to score and diagnostic for Sr36 in a set of 76 wheat cultivars and breedling lines developed in 12 countries. Together, these markers can be used in marker-assisted selection of Sr36.