Objective
1. Identify strong biocontrol candidates by screening beneficial microbes known to suppress soil-borne pathogens. These strains will be evaluated for their ability to produce natural antimicrobial compounds that inhibit V. longisporum.
2. Test single and combined biocontrol treatments, including mixtures of beneficial microbes and plant extracts. These combinations are expected to improve disease suppression, adapt to different field conditions, and better colonize plant roots and soil.
3. Understand how biocontrol strengthens plant immunity by studying how selected treatments activate natural defense pathways in canola. This will help identify which biological products promote long-term resistance to the disease.
4. Discover new beneficial microbes from Prairie soils by exploring canola root and soil microbiomes in Manitoba fields. Fields naturally showing low disease will be studied to isolate new microbial species associated with disease suppression.
5. Develop integrated strategies that combine the best biocontrol agents with resistant canola varieties and farm practices such as crop rotation and soil amendments to improve long-term effectiveness.
Project Description
Current control methods for V. longisporum on canola involve various protocols to prevent its spread, such as sanitation of farm equipment and tools, monitoring off-farm traffic, monitoring the source of seed and fertilizer, using plastic boots, and cleansing small tools with Virkon. However, effectively managing Verticillium stripe requires a comprehensive approach that includes chemical and biological control, crop rotation, weed management, and host resistance. The understanding of V. longisporum resistance in Canadian canola cultivars is currently limited. Chemical control is challenging due to the pathogen’s colonization in the xylem, where fungicides cannot reach without harming the host. The rhizosphere microbiomes play vital roles in enhancing plant tolerance to both biotic and abiotic stresses, demonstrating antagonistic effects on plant pathogens, and inducing plant defense-related genes. Specific bacterial species like Serratia plymuthica and Paenibacillus alvei have shown control of V. longisporum through mechanisms such as chitinase production and the induction of systemic resistance in host plants. The use of biocontrol agents is highly desirable for preventing V. longisporum infection, especially in the absence of resistant cultivars and efficient fungicides. Microorganisms like V. isaacii and Microsphaeropsis ochraceahave have shown potential as biological control agents by reducing symptom development and plant tissue colonization by V. longisporum. The combination of Trichoderma harzianum and Bacillus velezensis in rapeseed plants resulted in a synergistic effect, leading to the activation of the jasmonic acid and ethylene hormone signal transduction pathways, effectively limiting the infection caused by V. longisporum.
Previous research in our laboratory has demonstrated the effectiveness of various biological agents in controlling Verticillium wilt in potatoes. For example, Pseudomonas fluorescens, Bacillus pumulis, and an extract from the Canada milkvetch plant exhibited successful results in managing the disease in both controlled growth room experiments and field trials. The combination of Streptomyces hygroscopicus with phosphite also demonstrated a significant reduction in Phytophthora sojae infection in soybeans. In this project, we plan to use biocontrol tools for which we had proven efficacy against V. dahliae and test them against V. longisporum. These include naturally occurring soil-borne microbes, their byproducts, and plant extracts used as biocontrol agents to suppress the disease while minimizing harm to the environment and non-target organisms.
