Mapping of Crown Rust ( f. sp. ) Resistance Gene and a Novel Quantitative Trait Locus Effective Against Powdery Mildew ( f. sp. ) in the Oat () Line Pc54.

The Pc54 oat line carries the crown rust resistance gene and an unknown gene effective against powdery mildew. In this study, two recombinant inbred line (RIL) populations were developed to identify the genomic locations of the two genes and produce lists of molecular markers with a potential for marker-assisted selection. The RILs and parents were phenotyped for crown rust and powdery mildew in a controlled environment. They were also genotyped using the 6K Illumina Infinium iSelect oat single nucleotide polymorphism (SNP) chip. Multiple interval mapping placed on the linkage group Mrg02 (chromosome 7D) and the novel powdery mildew quantitative trait locus (QTL) on Mrg18 (chromosome 1A) both in mapping and in the validating populations. A total of 9 and 31 significant molecular markers were identified linked with the gene and , respectively. Reactions to crown rust inoculations have justified separate identities of from other genes and QTLs that have previously been reported on Mrg02 except for . is the only powdery mildew resistance gene previously mapped on Mrg18. However, the differential line, Mostyn, was susceptible to the powdery mildew race used in this study, suggesting that and are different genes. Determining the chromosomal locations of and is helpful for better understanding of the molecular mechanism of resistance to crown rust and powdery mildew in oats. Furthermore, SNPs and single sequence repeats that are closely linked with the genes could be valuable for developing PCR-based molecular markers and facilitating the utilization of these genes in oat breeding programs.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.