Transcriptomic Identification and Expression Profile Analysis of Odorant-Degrading Enzymes from the Asian Corn Borer Moth, Ostrinia furnacalis

SIMPLE SUMMARY: Ostrinia furnacalis, the Asian corn borer moth, is a major insect pest of corn. The O. furnacalis adults use their olfactory system in complex physiological behaviors, including host search, mating, and oviposition. However, the mechanisms underlying odor signal termination in O. furnacalis remain largely unknown. This study aimed to unravel the odorant-degrading enzymes (ODEs) associated with odor signal inactivation in the antennae of O. furnacalis. By searching the antennal transcriptome, we identified a large number of genes encoding ODEs. Furthermore, the expression patterns of carboxylesterase in different adult tissues were examined to identify male- or female-biased genes. The findings of this study indicate the potential involvement of ODEs in the olfactory system of O. furnacalis and may help to develop novel pest management strategies. ABSTRACT: The Asian corn borer moth Ostrinia furnacalis is an important lepidopteran pest of maize in Asia. Odorant-degrading enzymes (ODEs), including carboxylesterases (CCEs), glutathione S-transferases (GSTs), cytochrome P450s (CYPs), UDP-glycosyltransferases (UGTs), and aldehyde oxidases (AOXs), are responsible for rapid inactivation of odorant signals in the insect antennae. In this study, we performed a transcriptome assembly for the antennae of O. furnacalis to identify putative ODE genes. Transcriptome sequencing revealed 35,056 unigenes, and 21,012 (59.94%) of these were annotated by searching against the reference sequences in the NCBI non-redundant (NR) protein database. For functional classification, these unigenes were subjected to Gene Ontology (GO), Eukaryotic Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations. We identified 79 genes encoding putative ODEs: 19 CCEs, 17 GSTs, 24 CYPs, 13 UGTs, and 6 AOXs. BLASTX best hit results indicated that these genes shared quite high amino acid identities with their respective orthologs from other lepidopteran species. Reverse transcription-quantitative PCR showed that OfurCCE2, OfurCCE5, and OfurCCE18 were enriched in male antennae, while OfurCCE7 and OfurCCE10 were enriched in female antennae. OfurCCE14 and OfurCCE15 were expressed at near-equal amounts in the antennae of both sexes. Our findings establish a solid foundation for future studies aimed at understanding the olfactory functions of these genes in O. furnacalis.