Terminal fatty-acyl-CoA desaturase involved in sex pheromone biosynthesis in the Winter Moth (Operophtera brumata)

The Winter Moth (Operophtera brumata L., Lepidoptera: Geometridae) utilizes a single hydrocarbon, 1,Z3,Z6,Z9-nonadecatetraene, as its sex pheromone. We tested the hypothesis that a fatty acid precursor, Z11,Z14,Z17,19-nonadecanoic acid, is biosynthesized from α-linolenic acid, through chain elongation by one 2-carbon unit, and subsequent methyl-terminus desaturation. Our results show that labeled α-linolenic acid is indeed incorporated into the pheromone component in vivo. A fatty-acyl-CoA desaturase gene that we found to be expressed in the abdominal epidermal tissue, the presumed site of biosynthesis for type II pheromones, was characterized and expressed heterologously in a yeast system. The transgenic yeast expressing this insect derived gene could convert Z11,Z14,Z17-eicosatrienoic acid into Z11,Z14,Z17,19-eicosatetraenoic acid. These results provide evidence that a terminal desaturation step is involved in the winter moth pheromone biosynthesis, prior to the decarboxylation.