Genome-wide identification and characterization of the chemosensory relative protein genes in Rhus gall aphid Schlechtendalia chinensis

Abstract

AbstractBackgroundTheRhusgall aphidSchlechtendalia chinensisspecially uses the only speciesRhus chinensisand certain moss species (Mniaceae) as its primary host plant and secondary host plants, respectively.Rhusgalls are formed on the primary host by the sucking of aphids, and used in traditional medicine as well as other various areas due to their high tannin contents. Chemoreception is critical for insect behaviors such as host searching, location and identification of mates and reproductive behavior. The process of chemoreception is mediated by a series of protein gene families, including odorant-binding proteins (OBPs), chemosensory proteins (CSPs), olfactory receptors (ORs), gustatory receptors (GRs), ionotropic receptors (IRs), and sensory neuron membrane proteins (SNMPs). However, there have been no reports on the analysis of molecular components related to the chemoreception system ofS. chinensisat the genome level.ResultsWe examined the genes of eight OBPs, nine CSPs, 24 ORs, 16 GRs, 22 IRs, and five SNMPs in theS. chinensisgenome using homological searches, and these chemosensory genes appeared mostly on chromosome 1. Phylogenetic and gene number analysis revealed that the gene families, e.g., ORs, GRs, CSPs and SNMPs inS. chinensis, have experienced major contractions by comparing toMyzus persicae,while the two gene families OBPs and IRs had slight expansion. The current results might be related to the broader host range ofM. persicaeversus the specialization ofS. chinensison only a host plant. There were 28 gene pairs between genomes ofS. chinensisandAcyrthosiphon pisumin the chemoreceptor gene families by collinear comparison. Ka/Ks ratios (< 1) indicated that the genes ofS. chinensiswere mainly affected by purification selection during evolution. We also found the lower number and expression level of chemoreception genes inS. chinensisthan in other 11 aphid species, such as ORs, GRs and IRs, which play an important role in host search.ConclusionOur study firstly identified the genes of the different chemosensory protein gene families in theS. chinensisgenome, and analyzed their general features and expression profile, demonstrating the importance of chemoreception in the aphid and providing new information for further functional research.