Identification of biotransformation enzymes in the antennae of codling moth Cydia pomonella

Biotransformation enzymes are found in insect antennae and play a critical role in degrading xenobiotics and odorants. In Cydia pomonella, we identified 26 biotransformation enzymes. Among these enzymes, twelve carboxylesterases (CXEs), two aldehyde oxidases (AOXs) and six alcohol dehydrogenases (ADs) were predominantly expressed in antennae. Each of the CpomCXEs presents a conserved catalytic triad "Ser-His-Glu", which is the structural characteristic of known insect CXEs. CpomAOXs present two redox centers, a FAD-binding domain and a molybdenum cofactor/substrate-binding domain. The antennal CpomADs are from two protein families, short-chain dehydrogenases/reducetases (SDRs) and medium-chain dehydrogenases/reducetases (MDRs). Putative catalytic active domain and cofactor binding domain were found in these CpomADs. Potential functions of these enzymes were determined by phylogenetic analysis. The results showed that these enzymes share close relationship with odorant degrading enzymes (ODEs) and resistance-associated enzymes of other insect species. Because of commonly observed roles of insect antennal biotransformation enzymes, we suggest antennal biotransformation enzymes presented here are candidate that involved in degradation of odorants and xenobiotics within antennae of C. pomonella.