Alternative suppression of transcription from two desaturase genes is the key for species-specific sex pheromone biosynthesis in two Ostrinia moths

Crossing of two Ostrinia moths that use different positional isomers as sex pheromone components revealed that species-specific pheromone is produced through alternative suppression of two pheromone gland-specific desaturases at the gene transcription level. The sex pheromone of Ostrinia scapulalis (the adzuki bean borer) is a blend of (Z)-11- and (E)-11-tetradecenyl acetates (Z/E11-14:OAc), whereas that of Ostrinia furnacalis (the Asian corn borer) is a blend of (Z)-12- and (E)-12-tetradecenyl acetates (Z/E12-14:OAc). Δ11-Desaturase is known to be involved in the biosynthesis of Z/E11-14:OAc, and Δ14-desaturase, in that of Z/E12-14:OAc. The F1 hybrid between O. scapulalis and O. furnacalis produced both parents' sex pheromone components (Z/E11-14:OAc and Z/E12-14:OAc). Although the two species have both Δ11- and Δ14-desaturase genes, transcription from the Δ14-desaturase gene was strongly suppressed in O. scapulalis, as was transcription from the Δ11-desaturase gene in O. furnacalis. Meanwhile, both genes were transcribed into mRNA in F1. The production/non-production of Z/E11-14:OAc and Z/E12-14:OAc in F1, F2, and backcross progenies could be explained by an autosomal locus that suppresses transcription from either the Δ11-desaturase or Δ14-desaturase gene. Based on the findings, the evolution of sex pheromone biosynthesis in O. scapulalis and O. furnacalis is discussed.