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.
The proposed research will characterize CR genes based on genome-wide association analyses between clubroot disease data and the whole genome sequence (WGS) data from UA clubroot resistance donors and 28 Brassica hosts available from the National Center for Biotechnology Information (NCBI) and Brassica database (BRAD) websites.
Engineering apomixis, the asexual reproduction through seeds without fertilization, will provide major advances to plant breeding. This is a technology which could quickly capture and maintain valuable genotypes and associated traits without inbreeding depression and help select for traits not available to current breeding strategies.
Clubroot disease significantly affects canola seed quality by reducing oil content and seed weight. The most effective solution to control this disease today is growing clubroot-resistant (CR) cultivars in appropriate rotations.
Droughts in 2001, 2008 and 2021 adversely affected crop production in Saskatchewan. Canola’s resilience to heat and drought depends on when these stresses occur within the crop lifecycle. Plants may recover after stress during the vegetative stage, but stress during flowering and/or pod development usually has a negative effect on yield.
The proposed research we propose builds on an approach that promises to significantly enhance current knowledge of the mechanisms by which the clubroot pathogen causes disease and provides a new functional genomics tool to the research community.
As with many crops, canola faces increasing challenges due to unpredictable environmental changes, notably last year drought conditions were prevalent, while in 2022 high heat stress during flowering and pod filling is likely to cause yield losses.
