Identification and characterization of uridine diphosphate glycosyltransferases in Dioryctria abietella, with an emphasis on putative roles in olfaction and reproduction

Multiple physiological processes are involved in the interactions between the herbivore Dioryctria abietella and Pinaceae plants, with a key adaptation being the metabolic detoxification of host plant defensive substances. Moreover, the synthetic insecticides applied to control this coneworm are also shaping genes related to detoxification, such as the uridine diphosphate (UDP) glycosyltransferase (UGT) genes. Yet, the molecular mechanisms underpinning the resistance of D. abietella to toxic compounds remain unknown. In this study, we present an important UGT gene family involved in the detoxification mechanisms of D. abietella. Combining bioinformatic and transcriptomic approaches, a total of 37 UGT-coding genes were identified from the transcriptome of D. abietella, with 20 full-length sequences that shared high homology with UGTs found in other pyralid moths. These DabiUGTs were phylogenetically clustered into 12 subfamilies, with the three small clusters in the UGT33 and UGT40 clades mainly contributing to the size of the UGT gene repertoire in D. abietella. Expression profiles obtained from RNA sequencing (RNA-Seq), reverse transcription PCR (RT-PCR) and quantitative real-time PCR (qPCR) revealed that over half of DabiUGTs had a broad tissue expression profile, with 28, 28, 31 and 35 genes detected separately in antennae, legs, abdomens and reproductive tissues. Notably, DabiUGT20, DabiUGT25, DabiUGT28 and DabiUGT34 were all significantly enriched in the antennae. Several DabiUGTs had significant expression levels in reproductive tissues, including DabiUGT6, DabiUGT9, DabiUGT24, DabiUGT26 and DabiUGT32 in female accessory glands, DabiUGT15 in male accessory glands and DabiUGT25 in male testes. Altogether, our results identify candidate DabiUGTs for mediating olfaction and reproduction in D. abietella, warranting further investigation into the roles of DabiUGTs in pesticide resistance, odorant detection and reproduction.