MANNING GENES FOR RESISTANCE TO BARLEY STRIPE RUST (PUCCINIA-STRIIFORMIS F SP HORDEI)

Two genes conferring resistance to the barley stripe rust found in Mex ico and South America, previously identified as race 24, were mapped t o the M arms of barley chromosomes 7 and 4 in a doubled haploid popula tion using molecular markers and the quantitative trait loci (QTL) map ping approach. The resistance gene on chromosome 7 had a major effect, accounting for 57% of the variation in disease severity. The resistan ce gene on chromosome 4 had a minor effect, accounting for 10% of the variation in trait expression. Two pairs of restriction fragment lengt h polymorphism markers are being used to introgress the resistance gen es to North American spring barley using molecular marker-assisted bac kcrossing.