Identification And Expression Profile Analysis Of Olfactory Genes In Anoplophora Chinensis (Forster)

Anoplophora chinensis(Forster)is considered to be a great harmful wood-boring pest,native to China,Japan,and North Korea,and has recently spread to Europe.It has a very broad range of host plants(>100 species).Insects have a highly sensitive and sophisticated olfactory system that can finish various physiological behaviors,such as finding hosts,oviposition sites,escaping predators,seeking a mate and foraging by sensing and recognizing odorant substance from external environment.Several olfaction-related genes help insects to recognize the odors,including odorant binding proteins(OBPs),chemosensory proteins(CSPs),odorant receptors(ORs),gustatory receptors(GRs),ionotropic receptors(IRs),sensory neuron membrane proteins(SNMPs),odorant degrading enzymes(ODEs).Deep understanding these proteins in A.chinensis chemoperception will facilitate the development and application of more effective pest control strategies.In the current study,we assembled the antennal transcriptome of A.chinensis by Illumina sequencing.Based on bioinformatics method,olfaction-related genes were identified from transcriptome.Expression patterns of chemosensory receptors(ORs,GRs,IRs)on different tissues of both male and female A.chinensis were performed using quantitative real time-PCR(RT-qPCR).1)Antennae transcriptome sequencing and analyzing in A.chinensis.Illumina sequencing generated a total of 44,938 unigenes with an average length of902 bp.26,701 unigenes(59.41%)were compared to proteins in the NCBI nonredundant(nr)protein database.Homology analysis with other insect species revealed that Tribolium castaneum was the best match(55.6%),followed by Dendroctonus ponderosae(14.4%).48.52%(21,808)of unigenes were assigned to three GO functional categories,and KO annotation was used to classify 12,777(28.43%)unigenes into five branches of the KEGG pathway.2)Identification of putative olfactory genes in A.chinensis.Overall,211 Putative olfactory genes were identified from A.chinensis antennae transcriptome,including 52 putative odorant binding proteins(OBPs),14 putative chemosensory proteins(CSPs),53 putative odorant receptors(ORs),17 putative gustatory receptors(GRs),four putative ionotropic receptors(IRs),three putative Sensory neuron membrane proteins(SNMPs),25 putative Carboxylesterases(CXEs),43glutathione-S-transferase(GSTs).3)Tissue-and sex-specific expressions of putative chemosensory receptors in A.chinensis.Expression patterns of chemosensory receptors(53 ORs,17 GRs,4 IRs)in A.chinensis antennae,maxillary palps,labial palps,and the remaining insect bodies of both sexes were determined using RT-qPCR.41 putative OR genes were significantly expressed in the beetle antennae,of which antennal expression of eight OR sequences was significantly female biased,antennal expression of 23 OR sequences was significantly male-biased,and the remaining ten OR sequences were expressed at the same or similar levels in both female and male antennae.11 of the 17 GR genes showed significantly higher expression in beetle antennae,while AchiGR2 expression in female labial palps was significantly higher than in any other tissues.Two IR sequences showed the highest expression in antennae,and the other two IR sequences showed similar expression levels among all tested tissues.