Localization of the Stem Rust Resistance Gene to Linkage Group Mrg20 in Cultivated Oat ().

Stem rust is an important disease of cultivated oat () caused by f. sp. . In North America, host resistance is the primary strategy to control this disease and is conferred by a relatively small number of resistance genes. is a widely deployed stem rust resistance gene that originates from cultivated oat. Oat breeders wish to develop cultivars with multiple genes to slow the breakdown of single gene resistance, and often require DNA markers suited for marker-assisted selection. Our objectives were to (i) construct high density linkage maps for a major oat stem rust resistance gene using three biparental mapping populations, (ii) develop Kompetitive allele-specific PCR (KASP) assays for -linked single-nucleotide polymorphisms (SNPs), and (iii) test the prediction accuracy of those markers with a diverse panel of spring oat lines and cultivars. Genotyping-by-sequencing SNP markers linked to were identified in an AC Morgan/CDC Morrison recombinant inbred line (RIL) population. -linked SNPs were then analyzed in an AC Morgan/RL815 F population and an AC Morgan/CDC Dancer RIL population. Linkage analysis identified a common location for in all three populations on linkage group Mrg20 of the oat consensus genetic map. The most predictive markers were identified and converted to KASP assays for use in oat breeding programs. When used in combination, the KASP assays for the SNP loci avgbs2_126549.1.46 and avgbs_cluster_23819.1.27 were highly predictive of status in panel of 54 oat breeding lines and cultivars.