Table_1_Comparative Genomics Provide Insights Into Function and Evolution of Odorant Binding Proteins in Cydia pomonella.xlsx

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.

昆虫嗅觉对于觅食、交配、寄主搜寻以及躲避天敌/病原体至关重要。在昆虫体内，气味结合蛋白（odorant binding proteins, OBPs）负责将疏水性气味分子从外界环境转运至受体神经元。苹果蠹蛾（Cydia pomonella）是极具破坏性的果树害虫之一，可造成巨额经济损失。但目前学界对苹果蠹蛾气味结合蛋白基因的数量、种类、得失情况及演化历程仍知之甚少。本研究通过基因组与转录组分析，在苹果蠹蛾体内鉴定出40个气味结合蛋白基因，其中75%为经典型气味结合蛋白。基于基因得失分析，相较于鳞翅目类群的潜在远祖，苹果蠹蛾丢失了2个气味结合蛋白基因。系统发育树与染色体定位分析结果显示，气味结合蛋白基因的扩张主要源于串联重复事件：CpomGOBP2基因发生了两次复制，同时伴随CpomPBPB的丢失。研究还鉴定出CpomGOBP1基因存在2个正选择位点，其余气味结合蛋白基因则处于净化选择压力之下。本研究结果为苹果蠹蛾气味结合蛋白基因的相关研究提供了基础理论依据，可为后续深入解析其功能奠定重要基础。