Identification and Comparative Study of Chemosensory Genes Related to Host Selection by Legs Transcriptome Analysis in the Tea Geometrid Ectropis obliqua

Abstract

Host selection by female moths is fundamental to the survival of their larvae. Detecting and perceiving the non-volatile chemicals of the plant surface involved in gustatory detection determine the host preference. In many lepidopteran species, tarsal chemosensilla are sensitive to non-volatile chemicals and responsible for taste detection. The tea geometrid Ectropis obliqua is one devastating chewing pest selectively feeding on limited plants, requiring the specialized sensors to forage certain host for oviposition. In present study, we revealed the distribution of chemosensilla in the ventral side of female fifth tarsomere in E. obliqua. To investigate its molecular mechanism of gustatory perception, we performed HiSeq 2500 sequencing of the male- and female- legs transcriptome and identified 24 candidate odorant binding proteins (OBPs), 21 chemosensory proteins (CSPs), 2 sensory neuron membrane proteins (SNMPs), 3 gustatory receptors (GRs) and 4 odorant receptors (ORs). Several leg-specific or enriched chemosensory genes were screened by tissue expression analysis, and clustered with functionally validated genes from other moths, suggesting the potential involvement in taste sensation or other physiological processes. The RPKM value analysis revealed that 9 EoblOBPs showed sex discrepancy in the leg expression, 8 being up-regulated in female and only 1 being over expressed in male. These female-biased EoblOBPs indicated an ecological adaption related with host-seeking and oviposition behaviors. Our work will provide basic knowledge for further studies on the molecular mechanism of gustatory perception, and enlighten a host-selection-based control strategy of insect pests.

Sensory genes identification with head transcriptome of the migratory armyworm, Mythimna separata

“…The GO assignment results of classification of predicted functions in M. Separata were consistent with that of other invertebrates13141516171819. As regard to the number of the identified sensory genes, there was no statistical difference among M. Separata and other Lepidopteran, Dipteran, and Coleopteran species with identified transcriptome111718.…”

Identification of candidate chemosensory genes by transcriptome analysis in Loxostege sticticalis Linnaeus

“…However, the legs that also have a special olfaction sense though less sensitive than olfaction in the antennae [33, 34], its olfactory gene database seems incomplete for the L . sticticalis .…”

Expression patterns and colocalization of two sensory neurone membrane proteins in Ectropis obliqua Prout, a geometrid moth pest that uses Type‐II sex pheromones

“…SNMPs have been detected in the olfactory sensilla of moths (Rogers et al, 1997;Rogers, Krieger et al, 2001;Rogers, Steinbrecht et al, 2001) and were subsequently shown to be involved in sex pheromone detection in Drosophila (Benton et al, 2007;Jin et al, 2008;Li et al, 2014); their homologues have thus been extensively identified across lepidopteran species. However, the full-length sequences of these EoblSNMPs were not available online; in addition, other chemosensory genes in E. obliqua identified by Ma et al (2016), such as OBPs and CSPs, were confused with genes of its closely related species Ectropis grisescens . However, the full-length sequences of these EoblSNMPs were not available online; in addition, other chemosensory genes in E. obliqua identified by Ma et al (2016), such as OBPs and CSPs, were confused with genes of its closely related species Ectropis grisescens .…”

“…The reference genes Eoblβ-actin (Ma et al, 2016) and EoblGAPDH (Sun, Mao et al, 2017) were previously demonstrated to be suitable for estimating relative expression levels of E. obliqua olfactory genes; therefore, we selected them as housekeeping genes to normalize EoblSNMP1-2 gene expression and to correct for sample-to-sample variation. Negative controls were nontemplate reactions (sterilized H 2 O instead of cDNA).…”