Paving the way for plant-based bioproduction of (Z)-13-octadecenoic moth pheromone compounds

Sex pheromones are eco-friendly agents to control pest insects. Yet, the cost of synthetic pheromone production has restricted their use essentially to high value crops. Plant-based bioproduction of pheromone compounds offers a promising and sustainable alternative, opening up for the deployment of pheromone-mediated pest control also in row crops. The rice leaffolder Cnaphalocrocis medinalis uses C18 pheromone compounds and is a major rice pest in South China. We demonstrate that the fatty acid precursor of the main C18 pheromone component of C. medinalis, (Z)-13-octadecenal, can be biotechnologically produced using the oilseed crop Camelina sativa. First, we used deuterium-labelling to establish an elongation-based pathway for pheromone precursor formation from hexadecanoic (palmitic) acid via desaturation to (Z)-11-hexadecenoic acid and elongation to (Z)-13-octadecenoic acid. Using transient expression in Nicotiana benthamiana, we identified a minimal pathway consisting of a {Delta}11 desaturase (CmedDES1), an elongase (CmedELO1), and a fatty acyl reductase (CmedFAR2) for the heterologous biosynthesis of long-chain pheromone monounsaturated C18 precursors in planta. Co-expression of the insect desaturases CmedDES1 or CsupYPAQ with the Camelina elongase CsaKCS1 in Nicotiana benthamiana resulted in higher production of Z13-18 products compared to co-expression with insect elongases. We finally engineered Camelina sativa seeds through seed-specific co-expression of the Z11-16-forming insect desaturase CsupYPAQ and CsaKCS1 elongase, enabling the accumulation of C18 fatty acid pheromone precursors. Our study paves the way for sustainable production of the sex pheromone of C. medinalis and other C18 monounsaturated pheromone precursors for crop protection.