Transcriptome Analysis of Ostrinia furnacalis Female Pheromone Gland: Esters Biosynthesis and Requirement for Mating Success

Female moths use sex pheromones to attract males, and corresponding regulatory mechanism underlying sex pheromone biosynthesis is species-dependent. However, the detailed mechanism involved in sex pheromone biosynthesis in Ostrinia furnacalis has not yet been fully addressed. In the present study, transcriptome sequencing of O. furnacalis pheromone glands screened a serials of candidate genes involved in sex pheromone biosynthesis. Our analysis showed that sex pheromone release in O. furnacalis females arrives its peak at the 2nd scotophase, consistent with its mating behavior. Pheromone biosynthesis-activating neuropeptide (PBAN) was confirmed to regulate sex pheromone biosynthesis, and Ca2+ is the secondary messenger of PBAN signaling in O. furnacalis. The functional analysis of candidate genes demonstrated that the decreased mRNA levels or activities of calcineurin (CaN) and acetyl-CoA carboxylase (ACC) led to significant decrease in sex pheromone production and female capability to attract males, as demonstrated by RNAi-mediated knockdown and pharmacological inhibitor assay. Most importantly, the activities of CaN and ACC depend on the activation of PBAN/PBANR/Ca2+. Furthermore, fatty-acyl reductase 14 was involved in PBAN-mediated sex pheromone biosynthesis. Altogether, our results demonstrated that PBAN regulates sex pheromone biosynthesis through PBANR/Ca2+/CaN/ACC pathway to promote sex pheromone biosynthesis in O. furnacalis and provided a reference for non-model organism to study neuropeptide signal transduction.

Expansion of the fatty acyl reductase gene family shaped pheromone communication in Hymenoptera

The conserved fatty acyl reductase (FAR) family is involved in biosynthesis of fatty alcohols that serve a range of biological roles. In moths, butterflies (Lepidoptera), and bees (Hymenoptera), FARs biosynthesize fatty alcohol pheromones participating in mate-finding strategies. Using a combination of next-generation sequencing, analysis of transposable elements (TE) in the genomic environment of FAR genes, and functional characterization of FARs from Bombus lucorum, B. lapidarius, and B. terrestris, we uncovered a massive expansion of the FAR gene family in Hymenoptera, presumably facilitated by TEs. Expansion occurred in the common ancestor of bumblebees (Bombini) and stingless bees (Meliponini) after their divergence from the honeybee lineage. We found that FARs from the expanded FAR-A orthology group contributed to the species-specific male marking pheromone composition. Our results indicate that TE-mediated expansion and functional diversification of the FAR gene family played a key role in the evolution of pheromone communication in the crown group of Hymenoptera.AbbreviationsMMP: male marking pheromone, FA: fatty acid, FAME: fatty acid methyl ester, FAR: fatty acyl reductase, LG: labial gland, FB: fat body, TE: transposable element.