Abstract

Puccinia striiformis f. sp. hordei, the causal agent of barley stripe rust, is a destructive fungal pathogen that significantly affects barley cultivation. A major constraint in breeding resistant cultivars is the lack of mapping information of resistance (R) genes and their introgression into adapted germplasm. A considerable number of R genes have been described in barley to P. striiformis f. sp. hordei, but only a few loci have been mapped. Previously, Chen and Line (1999) reported two recessive seedling resistance loci in the Ethiopian landrace HOR 1428. In this study, we map two loci that confer resistance to P. striiformis f. sp. hordei in HOR 1428, which are located on chromosomes 3H and 5H. Both loci act as additive effect QTLs, each explaining approximately 20% of the phenotypic variation. We backcrossed HOR 1428 to the cv. Manchuria and selected based on markers flanking the RpsHOR128-5H locus. Saturation of the RpsHOR1428-5H locus with markers in the region found KASP marker K_1_0292 in complete coupling with resistance to P. striiformis f. sp. hordei and was designated Rps9. Isolation of Rps9 and flanking markers will facilitate the deployment of this genetic resource into existing programs for P. striiformis f. sp. hordei resistance.