Biotic Stress/Applied Plant Bio
CS-23-2 - Next generation molecular fungicides: Protecting crops using RNA interference technologies
Tuesday, July 17
8:53 AM - 9:13 AM
Infecting over 450 plant species, sclerotinia stem rot (white mold, Sclerotinia sclerotiorum) substantially threatens Canadian canola, which contributes over 26 billion dollars to the economy. Traditionally, Sclerotinia control involved the use of broad-spectrum fungicides, which are neither economical or effective. Crop rotations, which are also used, fail due to the promiscuous host range of Sclerotinia and the formation of durable, melanized resting structures called sclerotia, which persist in the soil for up to 10 years. Consequently, there is an urgent need for novel species-specific methods to mitigate Sclerotinia. Our novel strategy exploits the inherent cellular defense process known as RNA interference (RNAi) by employing in vitro or in planta synthesized double stranded RNAs (dsRNA). Upon encountering the designer molecules, the cell processes the dsRNA to specifically target homologous transcripts. Using a comprehensive bioinformatics pipeline, Sclerotinia genes were identified and Sclerotinia-specific dsRNA molecules were synthesized. Target gene knockdown was confirmed and quantified using quantitative real-time PCR from RNA isolated from fungal liquid cultures. Using a petal inoculation method that mimicked aggressive infection conditions, over 70 dsRNA molecules were evaluated. Lesion size was significantly reduced on mature leaf tissues by up to 85%. To protect plants throughout their lifecycle, we developed constitutively expressing dsRNA expressing Arabidopsis thaliana and Brassica napus. When challenged with Sclerotinia, transgenic RNAi plants reduced lesion size up 70% when compared to wild-type controls. Taken together, we have developed two novel solutions to combat this devastating fungus: a species-specific molecular fungicide capable of controlling fungal infection on the leaf surface and transgenic RNAi plants protected throughout the lifecycle.
Steve Whyard – University of Manitoba; Philip Walker – University of Manitoba; Austein Mcloughlin – University of Manitoba; Nick Wytinck – University of Manitoba