Expanding BnVQs (Valine-Glutamine) gene family against Sclerotinia sclerotiorum in canola

Term: 5 years
Status: Ongoing
Researcher(s): Zhongwei Zou, Wilfred Laurier University
SaskCanola Investment: $152,375
Total Project Cost: $304,750
Funding Partners: WGRF

Objective

The final goal of this project is to expand the candidate gene pools from the BnVQ family and to supplement Canadian canola germplasms with enhanced Sclerotinia Stem Rot (SSR) disease resistance. Additionally, we will be closely working with the growers and canola breeders to develop a molecular marker, which can quickly identify the functional BnVQs related to SSR resistance in canola germplasm. 

Project Description

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. In Western Canada, the average disease incidence was 14-30%. Over past several years, we observed the highest average SSR disease prevalence and incidence in 2016, resulting in a 7-15% yield loss. Sclerotinia stem rot is also the first important disease in winter canola, Ontario. Research indicated that for every unit percentage of SSR incidence, the potential yield loss was 0.5%. Also, the presence of sclerotinia may cause the downgrading of canola seeds. This will affect the seed export and profits from canola which impacts the income for growers. The survival of sclerotinia bodies in the field will also threaten the coming year’s crop such as soybean as rotated plants since S. sclerotiorum also can cause white mold disease in several other crop species. 

Current management strategies of SSR disease in canola heavily relies on cultural practice, such as crop rotation with non-host plants. Additionally, crop rotation should be incorporated with weed management to reduce the establishment of S. sclerotiorum in the absence of host crops. Fungicide is still the most effective way to reduce SSR disease incidence significantly. Several fungicide classes have been registered to control SSR in canola. Besides agricultural practices and fungicide application, some other microorganisms were used to suppress SSR disease as biocontrol agents. For example, two biological products Serenade OPTI and Contans were used in western Canada to disrupt the cell membrane growth of ascospores and hyphae, or reduce the viability of sclerotia in infected fields, respectively. However, these management strategies either are easily influenced by environmental factors or pose damage to soil health, which will eventually impact canola seed production due to poor soil fertility. Thus, genetic resistance is considered the most environment-friendly manner to control plant diseases. Unfortunately, there is no strong or complete resistance to SSR disease in Brassica napus. Even though a lot of QTLs (quantitative trait loci) have been identified in other Brassica species, none of these QTLs confer the full resistance to S. sclerotiorum, and the degrees of resistance vary under different environments and growth stages. Research also suggested that winter-type canola may exhibit high resistance to canola because of high glucosinolate content. There is a need to deploy functional/quantitative genes that are highly involved in SSR disease resistance, and therefore enhance the resistance through genetic modification. The transgenic intervention of functional genes in canola has very limited practice and success in the development of resistance lines against SSR disease. Additionally, genetic factors associated with petals and flowering time have been demonstrated to have the potential to reduce SSR susceptibility because the dropping of petals can initiate ascospore infections in canola plants. Therefore, exploring more genetic factors related to direct disease resistance or flowering and petal infection will be a valuable way to improve canola resilience against SSR.