Towards better understanding of genetics in Leptosphaeria-Brassica interactions via international collaborations to standardize the nomenclature of blackleg resistance genes
Term: 3 years, ending March 2024
Status: Complete
Researcher(s): Hossein Borhan, Gary Peng, AAFC; Dilantha Fernando, U of M
SaskCanola Investment: $105,000
Total Project Cost: $210,000
Funding Partners: ACPC, Manitoba SCAP
Grower Benefits
The best approach to manage blackleg disease is the use of canola cultivars that are genetically resistant to the pathogen. However, cultivars that contain the resistant (R) gene(s) against the most prevalent pathogen race(s) are more likely to be effective in controlling blackleg disease. Among the various tools developed from this and other similar projects, markers for race determination of blackleg pathogen and markers that determine the type of R gene in canola cultivars have the most practical and immediate benefit for canola farmers by helping them to achieve both goals.
Project Summary
Standardized tools and protocols developed during this project will help canola producers with better management of blackleg disease by knowing the race structure of most prevalent blackleg isolates in their fields and the profile of major resistance genes against blackleg in canola cultivars. An indoor Quantitative Trait Loci (QTL) test validated by this project and our collaborators will reduce the time required to identify and incorporate adult plant resistance (APR) genes into commercial canola varieties.
The two main objectives of this research project were to standardize the research protocols and consolidate research data and resistance gene naming systems developed by the international blackleg research community and to make available these protocols, resources, and information to canola breeders, agronomists, and farmers.
Five new Brassica napus (canola) lines with singe resistance (R) genes were developed and provided to canola breeders to generate canola varieties with highly effective R genes against blackleg. Additional markers for determining blackleg pathogen races and R gene profile of canola cultivars were developed and validated by the researchers of this project, as well as colleagues of blackleg research in Australia and France. Another tool validated by this project is an optimized indoor test to identify quantitative resistance (QTL or adult plant resistance) genes that significantly decrease the time and improve the accuracy of QTL screening and could expedite QTL discovery.
Molecular markers that differentiate changes in the sequence of target virulence genes in the pathogen and R genes in commercial canola varieties are valuable tools for canola farmers to determine the race structure of blackleg isolates in their field and available R-gene cultivars that works best against the most prevalent isolates in their field. These markers are offered by several private diagnostic labs in the prairie provinces.
R genes against blackleg were introduced into a common canola (B. napus) cultivar by repeated backcrossing. Five new lines were developed during this project increasing the total number of single R gene canola differential lines to 12. These lines are an excellent resource for breeders to provide farmers with many effective major R genes against blackleg disease. These lines are highly valuable for canola agronomists and pathologists to use as standard checks in blackleg disease nurseries across the prairies to determine the profile of blackleg races.
To maximize the efficiency of blackleg research and make accessible the research data and tools to canola breeders, Agronomists and farmers, a common set of blackleg pathogen races, Brassica napus lines with single R genes and tools such as markers for genotyping pathogen and plant as well as protocols for adult plant resistant (APR) gene screening were developed through a collaboration among the Canadian blackleg research labs and with the researchers in Australia and France. The most relevant outcomes of this collaborative research are:
Expanding the molecular marker sets for the blackleg pathogen race determination. In addition to markers for all the known blackleg virulence genes, a new marker was developed for the virulence gene AvrLms-Lep2. The disease phenotype of B. napus cultivars with the corresponding R gene Rlms or LepR2 is an intermediate reaction that could be mis-interpreted. However, the use of this marker allows accurate determination of pathogen races for the AvrRlms-Lep2 gene.
Developing molecular markers to determine the profile of R genes in commercial canola varieties.
Molecular markers against the R genes are highly valuable for canola agronomists to determine the R gene profile of available canola cultivars and inform the farmers on the use of best available cultivar(s).
Expediting discovery of new APRs and incorporation of these durable types of blackleg resistance to commercial canola cultivars. A round of this indoor screening method takes ten to twelve weeks to complete vs field-based screening that is one cycle per growing season. An additional advantage of the indoor APR test is eliminating environmental variations that impact the field results.