The genetic basis of resistance to barley grass yellow rust (Puccinia striiformis f. sp. pseudo-hordei) in Australian barley cultivars.

KEY MESSAGE: Resistance to Puccinia striiformis in 18 barleys was conferred by one or more genes. In two genotypes, resistance mapped to chromosomes 5HL and 7HL (seedling), and 5HS (adult plant). Twenty barley genotypes were assessed for resistance to a variant of P. striiformis [barley grass yellow rust (BGYR)] that is adapted to wild Hordeum sp. (barley grass) and is known to be virulent on several Australian barley cultivars. With the exception of Biosaline-19, all of the genotypes tested were resistant to BGYR. Genetic analyses of 16 Australian and three exotic barley lines indicated that each carried at least a single gene for resistance. Seedling resistance genes identified in the doubled haploid population developed from a cross between Franklin and Yerong were mapped to the long arm of chromosomes 5H and 7H, respectively. These genes were given the temporary designations of Rpsp-hFranklin and Rpsp-hYerong. Three QTL were detected in the same population when tested at the adult plant stage, two of them being in a similar position to Rpsp-hFranklin and Rpsp-hYerong and the third one was mapped to 5HS. Allelism tests between genotypes that exhibited seedling infection type responses to BGYR that were similar to Franklin and Yerong revealed that resistance in most were genetically independent of Rpsp-hFranklin and Rpsp-hYerong.