DOI 10.1007/s10681-007-9615-zMapping of the leaf rust resistance gene Lr38 on wheat chromosome arm 6DL using SSR markers

Abstract Leaf rust caused by the fungus Puccinia triticina is one of the most important diseases of wheat (Triticum aestivum) worldwide. The use of resistant wheat cultivars is considered the most eco-nomical and environment-friendly approach in con-trolling the disease. The Lr38 gene, introgressed from Agropyron intermedium, confers a stable seedling and adult plant resistance against multiple isolates tested in Europe. In the present study, 94 F2 plants resulting from a cross made between the resistant Thatcher-derived near-isogenic line (NIL) RL6097, and the susceptible Ethiopian wheat cultivar Kubsa were used to map the Thatcher Lr38 locus in wheat using simple sequence repeat (SSR) markers. Out of 54 markers tested, 15 SSRs were polymorphic between the two parents and subsequently genotyped in the popula-tion. The P. triticina isolate DZ7-24 (race FGJTJ), discriminating Lr38 resistant and susceptible plants, was used to inoculate seedlings of the two parents and the segregating population. The SSR markers Xwmc773 and Xbarc273 Xanked the Lr38 locus at a distance of 6.1 and 7.9 cM, respectively, to the proxi-mal end of wheat chromosome arm 6DL. The SSR markers Xcfd5 and Xcfd60 both Xanked the locus at a distance of 22.1 cM to the distal end of 6DL. In future, these SSR markers can be used by wheat breeders and pathologists for marker assisted selec-tion (MAS) of Lr38-mediated leaf rust resistance in wheat