Genetics of stripe rust resistance in a common wheat landrace Aus27492 and its transfer to modern wheat cultivars

Abstract The development of resistant cultivars is a preferred way to manage the wheat rust pathogens. Successful breeding relies on the continuous discovery, characterization and deployment of genetically diverse resistance sources. This investigation covers the identification and characterization of the stripe rust (caused by Puccinia striiformis f. sp. tritici) resistance carried by a pre-Green Revolution wheat genotype, Aus27492, from France and its transfer to modern backgrounds. Genetic analysis of stripe rust resistance using an F3 population derived from the cross of Aus27492 with the susceptible parent ‘Avocet S’ indicated digenic inheritance of all stage resistance. The underlying genes were tentatively named YrAW6 and YrAW7 and these loci were located in the long arms of chromosomes 2B and 5A, respectively, through the Illumina iSelect 90 K Infinium SNP genotyping array-based bulked segregant analysis (BSA). While YrAW7 was shown to be the same as the previously described stripe rust resistance gene Yr34 based on pathotypic specificity, YrAW6 appears to represent a new locus. To take these results from the laboratory to farmers’ fields, derivatives of Aus27492 in the Australian wheat cultivars ‘Emu Rock’, ‘Mace’ and ‘Suntop’ were delivered to Australian wheat-breeding companies for use as donor sources.