Multi-Functional Desaturases in Two Spodoptera Moths with Δ11 and Δ12 Desaturation Activities

Abstract

The beet armyworm, Spodoptera exigua, uses (Z,E)-9,12-tetradecadienyl acetate as the major component of its sex pheromone. Previous isotope-labeling experiments demonstrated an unusual Δ12 desaturase activity involved in the biosynthesis of this compound; however, the putative Δ12 desaturase gene has not been reported to date. In the present study, we confirmed this Δ12 desaturation pathway by in vivo labeling experiments, and characterized candidate desaturase genes in a yeast heterologous expression system. We demonstrated that a pheromone gland-specific desaturase, SexiDes5, uses palmitic acid and the subse-quently chain-shortened product (Z)-9-tetradecenoic acid as substrates to produce (Z)-11-hexadecenoic and (Z,E)-9,12-tetradecadienoic acids, respectively. In addition, the homologous desaturase SlitDes5 from the congeneric Spodoptera litura had analogous functions.