LOCALIZATION OF STEM RUST RESISTANCE GENES AND ASSOCIATED MOLECULAR MARKERS IN CULTIVATED OAT

Molecular markers have been identified in cultivated oat for the Pg9 a nd Pg13 loci conferring resistance to different races of the stem rust pathogen, Puccinia graminis f. sp. avenae. Near-isogenic lines and bu lked segregant analysis were used to identify putative restriction fra gment length polymorphism (RFLP) and random amplified polymorphic DNA markers. Linkage relationships were established in segregating populat ions derived from crosses of OT328 with Dumont (segregating for both P g9 and Pg13), Rodney 0 with Rodney 0-Pg9 (segregating for Pg9), and Ro dney 0 with Rodney 0-Pg13 (segregating for Pg13). The 5 markers linked to Pg9 exhibited from 0 to 2.7% recombination with the resistance loc us, and the 11 markers linked to Pg13 exhibited from 0 to 22.7% recomb ination. An oat avenin clone detected a RFLP marker linked to the Pg9 locus and an oat globulin clone detected a RFLP marker linked to the P g13 locus. Comparative mapping with an existing molecular linkage map of cultivated oat permitted localization of the Pg9 and Pg13 stem rust resistance genes. This is the first report of the localization of ste m rust resistance genes on the linkage map of cultivated oat.