Canola is the most important oilseed crop in Canada, but it is vulnerable to heat and drought stresses. These stresses may cause abnormal vegetative growth, flower abortion, abnormal siliques, and substantially reduced seed yield and quality in canola and other crops.
Clubroot is a major disease that threatens Canadian canola industry. Developing strong resistance and understanding the clubroot pathogen are top priorities for CARP research, which will lead to increase productivity.
Clubroot disease continues to spread on the Canadian prairies. Use of resistant cultivars combined with crop rotation is the only economical method to reduce production losses caused by the disease.
Verticillium stripe is an important vascular disease of canola caused by the soilborne fungus Verticillium longisporum. This disease was well established in Europe decades ago and has subsequently been reported in other major oilseed growing regions.
Conventional canola oil and the high oleic (HO) specialty oils are high quality vegetable oils very well suited for human consumption, food preparation and biofuel production. They offer the lowest saturated fatty acid content of any commodity oil with total saturate levels ranging from 7% to as low as 4.5% in some “Low Sat HO” varieties.
Verticillium longisporum is a soil-borne fungal pathogen that can infect a range of host plants, such as horseradish, canola, cabbage, and cauliflower. In canola, the fungus enters the plant through the roots and colonizes the vascular system, causing verticillium stripe (VS) disease.
Canola production is threatened by various diseases. Two of such disease are blackleg (BL) and Verticillium stripe (VS). Yield loss due to blackleg is estimated at 17.2% per every unit increase in disease severity.
Sclerotinia sclerotiorum, which causes Sclerotinia Stem Rot (SSR) or white mold diseases, is a devasting necrotrophic pathogen that infects a broad range of plant species, including soybean, cotton, sunflower, and canola. Sclerotinia stem rot disease is a major disease distributed across major canola/rapeseed/oilseed rape growing regions. This soil-borne disease is one of the major diseases in canola-growing regions in Canada.
The escalating frequency of drought conditions in the prairies is anticipated to exacerbate the prevalence and severity of Verticillium stripe disease. As a result, the threat posed by Verticillium stripe disease looms larger over canola production in the Canadian Prairies, necessitating diligent monitoring and proactive management strategies to safeguard crop yields and economic sustainability. Therefore, it is imperative to gain a comprehensive understanding of the genetic diversity and population structure of V. longisporum lineages prevalent in the prairies.
Access to genetic diversity is key to the success of crop breeding programs and, in this regard, the canola gene pool is particularly limited. This is due to the natural history of amphidiploid Brassica napus (AACC) being formed from an interspecific hybridization event between its diploid progenitor species B. rapa (A genome) and B. oleracea (C genome). This hybridization event(s) occurred recently (ca. 2000 years ago) meaning that there has been limited time for mutations and introgressions to occur and natural selection to increase the frequency of alleles required for further crop improvement. Canola breeders use a range of strategies to overcome this deficiency including mutagenesis, wide genetic crosses and crosses involving wild relatives.
Plasmodiophora brassicae is an obligate pathogen so must have a host to complete its life cycles and, by definition, cannot be grown in pure culture. The pathogen lives within the cells of its host throughout most its life cycle. Resting spores are produced in infected roots and are released into the soil as the roots decay. These represent the only source of pure pathogen available. However, when trying to get ‘clean’ cells for sequencing and other research, the P. brassicae material is generally contaminated with genes from plants and soil microbes which causes problems. A method to grow pure cultures of cells of P. brassicae, outside of the host, would be very useful for many types of research, and especially as a tool for selecting clubroot resistant canola lines, and advancing breeding canola for clubroot resistance.
Although planting resistant canola varieties is the primary approach for clubroot management, a growing number of clubroot pathotypes has emerged in recent years that can overcome host resistance, posing a significant challenge for growers. As such, it is critical to identify novel sources of resistance that are effective against these emerging strains of the pathogen. The identification of and breeding for resistance relies on testing host lines by inoculating them with the most prevalent and/or significant clubroot pathotypes on the Prairies.
