EsigGOBP1: The Key Protein Binding Alpha-Phellandrene in Endoclita signifer Larvae

The binding affinity of two general odorant binding proteins in Spodoptera frugiperda to general volatiles and insecticides

Spodoptera frugiperda is a kind of polyphagous pest, and can damage a large number different host plants around the worldwide. The molecular mechanisms of two general odorant binding proteins (GOBPs) binding with general volatiles and insecticides are still blank. In this study, we investigated the function of two GOBPs in S. frugiperda, by expressing two SfruGOBPs and tested the binding affinities by the fluorescence competition binding assays. The results exhibited that SfruGOBP1 has binding affinities to 4 of 38 general volatiles and 3 of 7 insecticides. In contrast, SfruGOBP2 showed a broader ligand-binding spectrum to 21 volatiles and 4 insecticides, suggesting SfruGOBP2 may plays a more important role in perceiving host volatiles than SfruGOBP1. Furthermore, we used molecular docking and site-directed mutagenesis assay to explored the key amino acid residues of two SfruGOBP to insecticides ligand. This study provides some valuable information to exploring the olfactory mechanism of two GOBPs bound the host plant volatiles and insecticides in S. frugiperda.

A Study of Adult Olfactory Proteins of Primitive Ghost Moth, Endoclita signifer (Lepidoptera, Hepialidae)

Endoclita signifer is a prominent wood-boring insect species in eucalyptus plantations in Guangxi, China, causing significant ecological and economic damage. A novel approach to controlling the challenging wood-boring pest involves disrupting the olfactory communication between insects and the volatile compounds emitted by plants. To identify the olfactory proteins contributing to host selection based on 11 GC-EAD-active volatiles from eucalyptus leaves and to discover the highly expressed olfactory proteins, we conducted a study on the antennal transcriptomes of adult E. signifer and screened key olfactory proteins in the antennae. We identified a total of 69 olfactory proteins. When compared to the larval transcriptomes, the antennal transcriptome of adult E. signifer revealed the presence of 17 new odorant-binding proteins (OBPs), including 2 pheromone-binding proteins (PBPs), 7 previously unreported chemosensory proteins (CSPs), 17 new odorant receptors (ORs), 4 new gustatory receptors (GRs), 11 novel ionotropic receptors (IRs), and 2 sensory neuron membrane proteins (SNMPs). Through the phylogenetic tree of OBPs and ORs, we identified EsigPBP2 and EsigPBP3 as two of the three PBPs, designated EsigOR13 as EsigOrco, and recognized EsigOR10 and EsigOR22 as the newly discovered EsigPRs in E. signifer. In the adult antennae, the expression levels of EsigGOBP14, EsigGOBP13, EsigOBP14, EsigOBP17, EsigCSP14, and EsigOR16 were notably high, indicating that these proteins could be pivotal in binding to plant volatiles.