Yu: Introgression of Disease Resistance from Brassica nigra into Canola using a new-type B. napus
Date: February 2019
Term: 4 years
Status: Completed
Researcher(s): Fengqun Yu, Gary Peng, Bruce Gossen, Sally Vail, Agriculture and Agri-Food Canada, Saskatoon SK
SaskCanola Investment: $110,814
Total Project Cost: $195,640
Funding Partners: ADF
Project Summary
New sources of clubroot and blackleg resistance are needed in western Canada because virulent pathogen populations have been reported that are able to overcome the resistance of canola cultivars for both diseases. Researchers in Saskatoon focused a four-year project on using black mustard (Brassica nigra) lines that were recently identified to carry resistance to both clubroot and blackleg. Overall, researchers successfully developed B. napus breeding lines with resistance to both diseases originating from black mustard. These breeding lines and molecular markers will be made available to canola breeders, and ultimately provide growers with access to new cultivars with the novel resistance genes in the future.
Two important diseases of canola, clubroot caused by Plasmodiophora brassicae and blackleg caused by Leptosphaeria maculans pose a serious threat to canola production in western Canada. New sources of clubroot and blackleg resistance are needed to manage these important diseases because virulent pathogen populations have been reported that are able to overcome the resistance of canola cultivars for both diseases.
Researchers with Agriculture and Agri-Food Canada (AAFC) in Saskatoon conducted a four-year project using Black mustard (Brassica nigra) lines that were recently identified to carry resistance to both clubroot and blackleg. These lines have never been utilized in canola or mustard breeding programs for disease resistance, indicating that it is a very unique and novel source of donor material for both clubroot and blackleg resistance. The objectives of the project were to determine how many genes control clubroot resistance and the genetic location of each resistance gene in the B. nigra line CR2716 (highly resistant to both clubroot and blackleg), and to discover SNP markets associated with each clubroot resistance gene. Researchers also wanted to develop B. napus breeding lines introgressed with resistance to clubroot and with resistance to blackleg.
In this study, genetic mapping of clubroot resistance in a B nigra line CR2716 was performed. Testing confirmed that resistance is controlled by a single dominant gene, and this novel clubroot resistance gene is highly resistant to pathotypes 3 and 5X, and potentially other new pathotypes. This novel resistance gene was mapped into a genomic region close to a previously identified clubroot resistance gene Rcr6. Researchers also identified more than 1000 high quality SNP sites in the target region. More than ten markers tightly linked to the resistance gene using KASP assay were developed.
The next part of the project focused on the introgression of resistance to both diseases from the B. nigra resistant line CR2716 into the B. napus canola line DH 16156. The clubroot breeding lines were tested for resistance to pathotypes 3 and 5X, and marker assisted selection was performed on each generation. A single gene was confirmed to control resistance to clubroot. Similar studies were performed for blackleg, with plant resistance identified in all populations. Four phenotypes for resistance to two isolates of L. maculans were found in most of the populations, indicating that blackleg resistance to isolates is likely controlled by different genes. Homozygous lines have been developed for both clubroot and blackleg resistant breeding lines.
Overall, the project successfully developed B. napus breeding lines with resistance to both diseases originating from black mustard or B. nigra. A novel resistance gene potentially with a broad spectrum of resistance to clubroot identified in black mustard was genetically mapped and molecular markers tightly linked to the gene were developed. The molecular markers and the B. napus breeding lines will be made available to canola breeders. In the future, growers can grow canola cultivars with the novel resistance genes, which will reduce economic losses due to the diseases.
Full Report PDF: Long report not available