Identification of candidate odorant‐degrading enzyme genes in the antennal transcriptome of Aphidius gifuensis

Abstract

Odorant-degrading enzymes (ODEs) have been found in insect antennae and play a critical role in signal chemical degradation once the message is conveyed. Significant progress has been made in characterizing ODEs in a variety of pests but very little is known in their natural enemies. We have carried out an antennae-and sex-specific transcriptome of Aphidius gifuensis, a natural enemy of aphid, to identify the candidate ODEs. Based on the antennae-and sex-specific transcriptome, a total of 100 putative ODEs were identified including one aldehyde oxidase (AOX), four alcohol dehydrogenases (ADs), eight UDP-glucuronosyltransferases (UGTs), 45 cytochrome P450 (P450s), nine glutathione S-transferases (GSTs) and 40 carboxylesterases (CCEs or CXEs). Additionally, we used RT-qPCR to determine the expression profiles of these genes in tissues of both sexes. Based on the phylogenic analysis and tissue-expression patterns, AgifEstE4, AgifCXE3, AgifCCE4, AgifCCE7, and AgifCCE18 were suggested as key ODEs in A. gifuensis. In addition, the female or male specifically enriched genes, such as AgifCCE17, AgifEstB1, AgifCYP18a1, AgifUGT2C2, were also considered to involve in the chemosensory processing in A. gifuensis. This study not only identified the candidate ODEs in A. gifuensis but also provided source for further exploration of the molecular mechanisms of chemical signal transductions in A. gifuensis, as well as other hymenopteran species.

Identification and Functional Analysis of Glutathione S-Transferases from Sitophilus zeamais in Olfactory Organ

“…The expression of the Tribolium is different in different tissues, and only TcasGSTe18 showed a high expression in the leg [ 28 ]. Our identified results are consistent with those of a previous study, in that 9 GSTs were identified in Aphidius gifuensis and Dendroctonus armandi [ 50 , 51 ], 12 cytosolic GSTs were identified in Cydia pomonella , and 16 GSTs were identified in the antennal transcriptome of Chilo suppressalis [ 25 , 27 ]. If the GSTs function in odorant degradation as the olfactory genes of insects, they will generally show preferential expression in the antennae.…”

Antennae-abundant expression of candidate cytochrome P450 genes associated with odorant degradation in the asian citrus psyllid, Diaphorina citri

“…Among the top twenty DEGs that were abundant in antennae, four transcripts were identified as OBP genes ( DcOBP1 , DcOBP6 , DcOBPA10 and DcOBP83a ), and two DEGs were CSP genes ( DcCSP4 and DcCSP10 ), this was consistent with the putative olfactory role of insect antennae. Antennal OBP and CSP genes have been reported in many other insect species including spotted-wing drosophila suzukii ( Ahn et al, 2020 ), ladybird Aphidius gifuensis ( Kang et al, 2021 ), as well as hemipteran aphid ( Zhou et al, 2010 ; Wang et al, 2019 ), hawthorn lace bug Corythucha ciliata ( Li G. W et al, 2018 ) and brown plant hopper Nilaparvata lugens ( Zhou et al, 2014 ). In green peach aphid Myzus persicae , three OBP genes ( MpOBP6/7/10 ) were specifically expressed in antennae, and five OBP genes ( MpOBP2/4/5/8/9 ) were expressed antennae enriched ( Wang et al, 2019 ).…”

Functional and Structural Diversity of Insect Glutathione S-transferases in Xenobiotic Adaptation

“…As odorant degrading enzymes (ODEs), GSTs play an important role in chemoreception for the adaptation to host plant volatiles and termination of stimulation from signals (i.e., sex pheromones and plant volatiles). Antenna expressed GSTs present in the sensillar lymph of insect antennae, function in signal termination and odorant clearance, enhancing olfactory and neuron sensitivity [103][104][105][106]. In Manduca sexta, an antenna specific GST, GST-msolf1 is expressed in the sex-pheromone-sensitive sensilla and can modify trans-2-hexenal, a plant derived green leaf aldehyde, suggesting its dual role in protecting sphinx moth olfactory system from harmful xenobiotics and pheromone inactivation [107].…”