P-116 - Harnessing dsRNA spray to protect canola against fungal pathogens

Brassica napus (canola, rapeseed) is the third most important oilseed crop, contributing an average of $43.7 billion annually to the Canadian economy. Blackleg (BL) and Verticillium stripe (VS), caused by the foliar fungus Leptosphaeria maculans (Lm) and the soil-borne fungus Verticillium longisporum (Vl), respectively, are major threats to canola. While several race-specific resistance (R) genes (Rlm and LepR) have been identified against Lm, resistance often breaks down within 3-4 years. Vl, first reported in Manitoba in 2014, is now widespread across the Canadian prairies, frequently co-occurring with Lm. Currently, no commercial canola cultivars offer resistance to Vl, nor are effective fungicides available for VS management. We explored spray-induced gene silencing (SIGS) as a novel approach to inhibit Lm and Vl growth. Using dsRNA targeting genes essential for fungal development, we selected eight Lm genes and identified their Vl orthologues. Our results demonstrated effective protection of the susceptible B. napus cv. Westar when sprayed with individual or combined dsRNAs prior to fungal inoculation. We will present data comparing the fungicidal effects of each dsRNA treatment, applied as a foliar spray.