Comparative Genomics Provide Insights Into Function and Evolution of Odorant Binding Proteins in Cydia pomonella.

Cong Huang,Xue Zhang,Fanghao Wan,Yu Xi,Dongfeng He,Bo Liu,Rui Tang,Longsheng Xing,Wanqiang Qian,Nianwan Yang,Wanxue Liu,Qiang Wu,Wenkai Wang

doi:10.3389/fphys.2021.690185

Abstract

Insect olfaction is vital for foraging, mating, host-seeking, and avoidance of predators/pathogens. In insects, odorant binding proteins (OBPs) are involved in transporting hydrophobic odor molecules from the external environment to receptor neurons. The codling moth, Cydia pomonella, one of the most destructive insect fruit pests, causes enormous economic losses. However, little is known about the number, variety, gains and losses, and evolution of OBP genes in C. pomonella. Here we report the identification of 40 OBPs in C. pomonella, most (75%) of which are classic OBPs, using genomic and transcriptomic analyses. Two OBP genes were lost in C. pomonella relative to possible distant ancestor in Lepidoptera lineage based on an analysis of gene gains and losses. The phylogenetic tree and chromosome location showed that the expansion of OBP genes mainly resulted from tandem duplications, as the CpomGOBP2 gene was duplicated twice along with loss of CpomPBPB. Two positive selection sites of the CpomGOBP1 gene were identified while other OBP genes evolved under purifying selection. Our results provide fundamental knowledge of OBP genes allowing further study of their function in C. pomonella.

Highlights

Insects rely on their olfactory system to sense environmental odors related to behaviors such as foraging, host-seeking, mating, and oviposition, as well as avoiding predators and pathogens (Andersson et al, 2015)
A total of 40 Odorant binding proteins (OBPs) genes were identified in the C. pomonella genome
Four CpomOBPs belong to the minus-C subfamily, which had fewer than six cysteines

Summary

Introduction

Insects rely on their olfactory system to sense environmental odors related to behaviors such as foraging, host-seeking, mating, and oviposition, as well as avoiding predators and pathogens (Andersson et al, 2015). Odorant Binding Proteins in Cydia pomonella lymph of insect olfactory sensilla (Pelosi et al, 2014). When lipophilic semiochemicals from the environment enter the lymph through micropores on the surface of olfactory sensilla, the OBPs bind, solubilize, and deliver the semiochemicals to the receptor proteins, e.g., odorant receptors (ORs) or ionotropic receptors (IRs), which are located on the membranes of olfactory sensory neurons. This delivery activates a series of downstream olfactory signal transductions accompanied by corresponding behavioral movements in insects (Zhang et al, 2020). OBPs are clearly essential in communications between insects and environmental semiochemicals including both pheromones and host volatiles

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Results

Conclusion