Oat is considered a healthy cereal due to nutritional compounds found within the grain, including beta-glucan (which has been shown to reduce the risk of heart disease), antioxidant avenanthramides (that may protect against coronary heart disease) and up to 20% protein which provides a better balance of essential amino acids compared to other cereals and is considered to be gluten-free. As a result of these desirable attributes, oat remains a significant western Canadian crop that has been seeded on an average of 3.6 million acres since 2018. This has translated to the oat industry having a direct impact on the Canadian economy of $1.4 billion and 7,000 jobs annually since 2018, with an indirect impact of $4.2 billion.

One of the largest threats to oat production in Canada is the fungal pathogen Puccinia coronata which causes crown rust. Yield losses in Canada have been reported at 5.1-11.2%, with losses up to 50% reported in the U.S. While agronomic practices, such as crop rotation, early seeding and fungicide application can reduce crown rust severity, incorporating genetic resistance is an economically advantageous strategy for conventional producers and is critical for organic producers.

To help breeders develop oat varieties with improved resistance to crown rust, this project aimed to develop molecular markers linked to seeding and adult resistance genes which would allow for easier selection and pyramiding of resistance. Bi-parental oat populations segregating for seven different Pc seedling resistance genes (Pc40, Pc46, Pc62, Pc63, Pc67, Pc98, Pc101) and adult plant resistance (APR) derived from ‘CDC Dancer’ were developed and evaluated for crown rust in growth chambers or field nurseries to understand the inheritance of resistance. Populations were subsequently genotyped using the Illumina Infinium SNP Assays and QTL mapped to identify the specific locations within the oat genome which were responsible for resistance. Each seedling resistance gene was mapped to a unique region of the oat genome while eight QTL associated with APR were across multiple years and crown rust nurseries, suggesting that these QTL are stable and thus good targets for selection. Finally, KASP assays were developed for four of the resistance genes which will allow for high throughput evaluation for the presence of these resistance genes in oat breeding programs. This project has provided important knowledge regarding the location of crown rust resistance genes within the oat genome, critical information for breeders wishing to pyramid several genes to provide more effective resistance, and provided tools (in the form of KASP assays) to allow efficient breeding for crown rust resistance. Ultimately, varieties with improved crown rust resistance will improve grower returns, via greater yield per acre and lower cost of production, and increase returns to oat millers, via the maintenance of grain plumpness and test weight.

Extension Messages

• the genomic locations of six Pc seedling resistance genes (Pc40, Pc46, Pc62, Pc63, Pc98, Pc101) were identified,
• none of the resistance genes reside at a common region within the oat genome, allowing them to be incorporated in different combinations in future oat varieties and thus potentially providing better crown rust resistance,
• molecular-marker assays for four of these genes are available which will help oat breeders to incorporate these genes into future oat varieties,
• crown rust resistance present in ‘CDC Dancer’ was governed by multiple genes, each with less influence on crown rust resistance than any of the individual seedling crown rust genes. The resistance in CDC Dancer, although providing less resistance than the Pc genes, is more durable.