Uncovering the genetic basis of crown rust resistance in a northern-by-southern oat biparental population

Abstract

Crown rust, caused by the fungal pathogen Puccinia coronata f. sp. avenae ( Pca ), is a destructive foliar disease of oat. Use of host resistance is the preferred method of disease management. However, frequent emergence of new Pca races has hindered crown rust management in oat. Identification and deployment of non-race-specific genetic resistance will aid oat breeding efforts to develop germplasm with durable crown rust resistance. To map and characterize crown rust resistance, a recombinant inbred line (RIL) population was developed from a cross between LA07065_SBSBSB_32-2 and CDC Dancer and evaluated for crown rust reaction in four field environments for two years. The RIL population was genotyped using the oat 6K Infinium iSelect single nucleotide polymorphism (SNP) array and a total of 956 polymorphic SNP markers were used to construct the linkage map. Quantitative trait loci (QTL) mapping detected a total of six QTL on chromosomes 2D, 4A, 7A, 7C, and 7D influencing crown rust resistance. Two of these QTL were validated using genotype-phenotype association analysis in an independent set of oat lines. The identified QTL demonstrated additive effects on crown rust resistance within the RIL population. A major QTL on chromosome 7C, QPca-ars-7C , was detected consistently across environments and explained up to 16.54% of the phenotypic variation. Markers linked to QPca-ars-7C, and other QTL detected in this study have the potential to be used in marker-assisted selection for crown rust resistance.