Gene set of chemosensory receptors in the polyembryonic endoparasitoid Macrocentrus cingulum.

Tofael Ahmed,Shuxiong Bai,Zhenying Wang,Kanglai He,Tiantao Zhang

doi:10.1038/srep24078

Abstract

Insects are extremely successful animals whose odor perception is very prominent due to their sophisticated olfactory system. The main chemosensory organ, antennae play a critical role in detecting odor in ambient environment before initiating appropriate behavioral responses. The antennal chemosensory receptor genes families have been suggested to be involved in olfactory signal transduction pathway as a sensory neuron response. The Macrocentrus cingulum is deployed successfully as a biological control agent for corn pest insects from the Lepidopteran genus Ostrinia. In this research, we assembled antennal transcriptomes of M. cingulum by using next generation sequencing to identify the major chemosensory receptors gene families. In total, 112 olfactory receptors candidates (79 odorant receptors, 20 gustatory receptors, and 13 ionotropic receptors) have been identified from the male and female antennal transcriptome. The sequences of all of these transcripts were confirmed by RT-PCR, and direct DNA sequencing. Expression profiles of gustatory receptors in olfactory and non-olfactory tissues were measured by RT-qPCR. The sex-specific and sex-biased chemoreceptors expression patterns suggested that they may have important functions in sense detection which behaviorally relevant to odor molecules. This reported result provides a comprehensive resource of the foundation in semiochemicals driven behaviors at molecular level in polyembryonic endoparasitoid.

Highlights

The ORs of both insects and vertebrates have seven transmembrane domains (TMDs), but insects ORs do not belong to the canonical G-protein coupled receptors (GPCRs), to which have a reversed membrane topology[8,22]
IRs are related to ionotropic glutamate receptors, which are involved in synaptic signal transduction in both vertebrates and invertebrates[20,34]
M. cingulum antennal transcriptomes generated of 2,73,13,634 and 2,64,69,263 clean reads respectively, and assembled to 57,179 transcripts and 41,254 unigenes with 1,571 bp and 982 bp mean length respectively (Table 1)

Summary

Introduction

The ORs of both insects and vertebrates have seven transmembrane domains (TMDs), but insects ORs do not belong to the canonical G-protein coupled receptors (GPCRs), to which have a reversed membrane topology (intracellular N-terminus)[8,22]. Multiple ORs have been identified in species from at least four insect orders, including Diptera, Lepidoptera, Hymenoptera and Coleoptera[23,24,25,26,27]. These ORs display a high divergence (only 20–40% identities) in their sequences among or within species[28]. The GRs are more conserved in sequence and structure than ORs35,36, probably due to a comparatively smaller search space on associated cues These GRs typically detect sugars, bitter compounds, and contact pheromones[37]. Several extensive studies have been described the characteristics and potential roles of these genes in insect olfaction[5,37,42,43,45,46]

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Discussion

Conclusion