Research Progress of Insect Odorant Receptors

For insects, olfaction is an important signal input source for their behavioral perception. There are many kinds of proteins involved in the process of odor recognition, and they play a leading role in regulating feeding, swarming, mating, oviposition and other behaviors of insects. These proteins include Odorant-binding Proteins (OBPs), Chemosensory Proteins (CSPs), Odorant Receptors (ORs), Ionotropic Receptors (IRs), Sensory Neuron Membrane Proteins (SNMPs) and Odorant Degrading Enzyme (ODE). Among them, ORs play a critical role in identifying odor molecules and transmitting olfactory signals downstream. The specific combination of odorant molecule and dendrites of olfactory sensory neurons (OSNs) mediated by odorant receptors is an important basis for olfactory recognition. Odorant receptors involves two types: conventional odorant receptors (ORs), and odorant receptor coreceptor (ORCO). ORs, a highly divergent family of receptors, have the ability to recognize odor molecule, and the homology is lower between different insects. ORCO, a receptor without odor sensitivity, co-expresses with ORs to recognize odor molecule, and its sequence is remarkably conserved among insect species. Cell line culture, voltage clamp technique and drosophila"empty neuron"method were used to verify the function of odor receptors. Research about odor receptors'function can lay a theoretical foundation for looking for odor ligands, development of food attractants and repellents against pests, sex attractants and aggregation pheromones and so on. This article reviews the research progress in identification and classification, structure, expression profile, phylogenetic relationships and function of odorant receptors in the domestic and overseas, which provides reference for the research of insect olfactory mechanism as well as the prevention and control of pests.