High-density molecular map of chromosome region harboring stripe-rust resistance genes YrH52 and Yr15 derived from wild emmer wheat, Triticum dicoccoides

Two stripe-rust resistance genes, YrH52 and Yr15, derived from the Israeli wild emmer wheat, Triticum dicoccoides, have been located on chromosome 1B. The main objectives of the present study were to increase marker density i n the vicinity of YrH52 gene by means of AFLP, RAPD and microsatellite mark ers, to improve the map of another T. dicoccoides-derived stripe-rust resis tance gene Yr15 using microsatellite markers, and to preliminarily discrimi nate these two genes. Additional 26 marker loci comprising 20 AFLPs, three RAPDs, and three microsatellites were found to be linked to YrH52 gene. An updated genetic map consisting of 45 marker loci, in the region of YrH52 ge ne, was constructed with a total map length of 107.7 cm. The mean interval length was 0.96 cm in the region Xgwm359b-P55M53b carrying YrH52 gene. YrH5 2 was bracketed by Xgwm413 (Nor1 and UBC212a) and Xgwm273a (Xgwm273d) with map distance of 1.3 and 2.7 cm from either side, respectively. Eight additi onal microsatellite markers were found to be linked with Yr15, and the link age map of Yr15 gene was thus obviously improved. In the YrH52-mapping popu lation, no crossover was detected in the interval UBC212a (Xgwm413)-Yr15-No r1, and YrH52 was located distally outside this interval. It may suggest th at YrH52 is different from Yr15 even though both of them are derived from T . dicoccoides and are mapped on chromosome 1BS. The large number of molecul ar makers revealed in the present study would be helpful for the marker-ass isted introgression of the T. dicoccoides-derived YrH52 and Yr15 stripe-rus t resistance genes into elite cultivars of wheat, and the high-density map would accelerate the map-based cloning of the two genes.