Microsatellite Marker Linked to a Leaf Rust Resistance Gene from Triticum monococcum L Transferred to Bread Wheat

Triticum monococcum L, a diploid wheat species closely related to the A genome of cultivated wheats, is highly resistant to leaf rust. A synthetic amphiploid, T. monococcum — T. durum was crossed with T. aestivum cv WL711, highly susceptible to leaf rust. Leaf rust resistant derivatives were selected among backcross generations with the recurrent parent WL711 and cytologically analysed. Chromosome number of the leaf rust resistant BC₁F₃ progenies varied from 39 to 44. Six leaf rust resistant and susceptible bulks from different BC₁F₃ progenies were analysed using 29 wheat microsatellite(WMS) markers already mapped on A genome of bread wheat and found polymorphic among parents. One T. monococcum specific allele of WMS gwm136 locus was found to be closely linked to the leaf rust resistance gene in all the resistant bulks. Differential chromosome number, frequency of univalents and multivalents, however, indicated that the critical T. monococcum chromosome might be present in addition to the A genome chromosomes of wheat, substituted either for the B or D genome chromosome of wheat or translocated to chromosome 1A of wheat in one or the other bulks. The association of the T. monococcum specific allele of WMS gwm136 locus to leaf rust resistance was further confirmed from bulked segregant analysis in BC₂F₁ generation.