Identification and characterization of the distinct expression profiles of candidate chemosensory membrane proteins in the antennal transcriptome of Adelphocoris lineolatus (Goeze).

Chemosensory membrane proteins, including odorant receptors (ORs), ionotropic receptors (IRs), gustatory receptors (GRs) and sensory neurone membrane proteins (SNMPs), are supposed to be crucial macromolecules in the insect olfactory signal transduction pathway. The alfalfa plant bug Adelphocoris lineolatus (Goeze) (Hemiptera: Miridae) is highly attracted to high-nitrogen or flowering plants and destroys many important agricultural crops. We assembled the antennal transcriptome of A. lineolatus using Illumina sequencing technology and identified a total of 108 transcripts encoding chemosensory membrane proteins (88 ORs, 12 IRs, four GRs and four SNMPs), amongst which 90 candidates appeared to be full length. Subsequently, both semiquantitative reverse transcription PCR and quantitative real-time PCR experiments were performed to investigate their tissue- and sex-biased expression profiles. The results showed that nearly all of the 108 candidate chemosensory membrane protein genes were largely expressed in adult antennae, and some genes additionally displayed significant differences in the expression levels between sexes. The results of our phylogenetic analysis and the detailed tissue- and sex-biased expression characteristics given here provide an important foundation for further understanding of the complex chemoreception system of the alfalfa plant bug and other Hemiptera species, which also could help us use chemosensory membrane proteins as targets to manipulate insect olfactory behaviour and broaden the applications of available tools for insect pest control.