Multiple Δ11-desaturase genes selectively used for sex pheromone biosynthesis are conserved in Ostrinia moth genomes

Abstract

Regulation of the expression of fatty acyl-CoA desaturases, which introduce a double bond into the fatty acid moiety of the substrate, is crucial for the production of species-specific sex pheromones in moths. In Ostrinia moths, two distinct Δ11-desaturases and a Δ14-desaturase are known to be selectively used in the biosynthesis of sex pheromones. Of the two Δ11-desaturases, one identified from Ostrinia nubilalis and Ostrinia scapulalis, Z/EΔ11, forms the Z and E isomers of a double bond at position 11, whereas the other identified from Ostrinia latipennis, LATPG1(=EΔ11), exclusively forms an E double bond at position 11. Since the retroposon(ezi)-fused, non-functional Δ11-desaturase gene, ezi-Δ11α, in the genomes of O. nubilalis and O. furnacalis was previously suggested to be an orthologue of latpg1, we here explored Z/EΔ11 orthologues in the genome of O. latipennis. We newly identified two Δ11-desaturase genes, latpg2 and latpg3, which were orthologous to ezi-Δ11β and Z/EΔ11, respectively. We found that an ezi-like element was integrated in intron 1 of latpg1, and confirmed that only latpg1 was expressed in the pheromone gland of O. latipennis. Thus, at least three Δ11-desaturase genes are present in the genome of O. latipennis, and latpg1 is selectively transcribed in the pheromone gland of this moth. The non-functionality of ezi-inserted desaturase genes in O. nubilalis and O. furnacalis may not be a direct consequence of the insertion of an ezi- or ezi-like element into the gene.