A Platform for Sustainable Production of Terpene-Based Biopesticides for Broad Acre Crop Applications

With the fast-growing world population and the negative impact of climate change on agriculture, food security is under a significant threat. Plant pests and pathogens pose further risks on crop production and countermeasures make heavy use of synthetic pesticides that are often harmful to human health and the environment. Commendably called "the molecules that changed the world", natural products have found wide applications and could present an extraordinary source of biologically active compounds to be used in crop protection. With a specific and complex mode of action, natural products are non-persistent in ecosystems and less toxic than synthetic pesticides. To date, several terpenoid-type natural products are successfully used for pest control (e.g. essential oils, azadirachtin or pyrethrin). Essential oils are active against the fleas, aphids, mites, ants, flies and crickets. However, these agrochemicals cannot replace synthetic pesticides in broad acre crops due to low availability and high production cost. Moreover, several terpenoid allelochemicals or plant protectors (e.g. momilactones, phytoalexins or saponins) are currently not in use due to scarcity of their supply.

This platform will enable efficient and low-cost production of terpenoid-based biopesticides by conventional yeast fermentation. Using synthetic biology and metabolic engineering approaches, dedicated yeast platforms will be engineered for biosynthesis of terpenoids with known biopesticide activities and scale-up of their bioprocesses for high yield production. These include – but are not limited to – components of essential oils (monoterpenes and sesquiterpenes) or labdane diterpene phytoalexins (momilactones). Subsequently, combinatorial high-throughput screening of terpenoid libraries will be performed against a panel of bacterial and fungal plant pathogens with high or medium prevalence in Quebec. Purified terpenoids or synergistic blends with antimicrobial activities will be loaded into halloysite nanotubes for prolonging shelf-life and improving performance under field application conditions. The performance of developed nanocomposite will be investigated against a large collection of plant pathogenic bacteria (e.g. Pseudomonas, Xanthomonas) and fungi (e.g. Godronia, Exobasidium). Iterative modification to nanomaterials or composition of terpenoids will be conducted to improve performance and their retention on plant leaves. The developed formulation will be tested against pathogens of interest to the industrial partner and beyond: a) Botryosphaeria fruit rot and berry speckle Botryosphaeria vaccinii; Proventuria Early Leaf Spot Proventuria barriae; c) Red leaf spot Exobasidium rostrupii; d) End rot Godronia cassandrae. Two phases of validation experiments will be performed to evaluate efficiency of synthetized terpenes-HNT encapsulated against fungal diseases in crop cultures under field conditions.

If made available in enough amounts by an economical green method, terpenoid-inspired pesticides could be used for pest control in the field, with a potential to replace synthetic pesticides in the next 10 years and reduce GHG emissions in the context of addressing concerns related to climate change.