Identification of diagnostic kompetitive allele-specific PCR markers for selection of crown rust resistance in oats

Crown rust disease, caused by Puccinia coronata f. sp. avenae, poses a significant threat to global oat (Avena sativa L.) production. Molecular markers are essential to assist in the integration of multiple resistance genes into a single oat cultivar to achieve genetic resistance durability. Here, we validated previously reported markers for the race-specific resistance genes Pc39, Pc45/PcKM, Pc54, and Pc68 and developed new kompetitive allele-specific PCR markers closely linked to these loci. These markers were subsequently screened across a collection of 150 oat cultivars. Analysis of molecular marker data, pedigree information, and disease resistance profiles identified several oat cultivars likely carrying Pc39 and Pc68. Newly identified carriers of Pc68 include the cultivars Galileo and Graza80, while Warrego, Kowari, Possum, Forester, Drummond, Hokonui, Glider, and Culgoa were identified as potential carriers of Pc39. Discrepancies between the previous postulation of Pc gene carriers and our phenotyping and genotyping analysis were also found. For example, the oat line Glider was previously postulated to carry Pc58 or Pc59, but it was positive for the Pc39-associated marker and had a similar resistance profile to Pc39 carriers. These findings underscore the importance of the utilization of molecular markers in tracking the resistance genes in breeding germplasm.