The olfactory system must detect and discriminate various semiochemicals in the environment. In response to such diversity, insects have evolved a family of odorant-gated ion channels composed of a common receptor (coreceptor, Orco) and a ligand-binding tuning odorant receptor (OR) that confers odour specificity. This study aims to examine the expression pattern of Orco gene of Grapholita molesta (GmolOrco) and to elucidate the role of GmolOrco in detecting G. molesta sex pheromone and green leaf volatiles by using gene silencing via RNA interference (RNAi) coupled antennal electrophysiological (EAG). Multiple sequence alignment showed that GmolOrco shared high sequence similarities with the Orco ortholog of lepidopterans. The results of real-time quantitative PCR detection demonstrated that GmolOrco was predominantly expressed in adult antennae and had the highest expression quantity in adult period among the different developmental stages. Compared with the noninjected controls, GmolOrco expression in GmolOrcodouble-stranded RNA (dsRNA)-injected males was reduced to 39.92% and that in females was reduced to 40.43%. EAG assays showed that the responses of GmolOrco-dsRNA injected males to sex pheromones (Z)-8-dodecenyl acetate (Z8-12:OAc) and (Z)-8-dodecenyl alcohol (Z8-12:OH) were significantly reduced, and the GmolOrco-dsRNA-injected female to green leaf volatile (Z)-3-hexenyl acetate also significantly declined. We inferred that Orco-mediated olfaction was different in male and female G. molesta adults and was mainly involved in recognizing the sex pheromones released by female moths.

中文翻译：

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气味受体辅助受体在 Grapholitamoleta（鳞翅目：Tortricidae）气味检测中的功能分析

嗅觉系统必须检测和区分环境中的各种化学信息素。为了应对这种多样性，昆虫进化出一系列气味门控离子通道，由一个共同受体（辅助受体，Orco）和一个赋予气味特异性的配体结合调节气味受体 (OR) 组成。本研究旨在检验的ORCO基因的表达模式梨小食心虫（GmolOrco），并阐明在检测GmolOrco的作用G.食心虫通过使用通过 RNA 干扰 (RNAi) 耦合触角电生理 (EAG) 进行基因沉默的性信息素和绿叶挥发物。多序列比对表明 GmolOrco 与鳞翅目 Orco 直系同源物具有高度的序列相似性。实时定量PCR检测结果表明，GmolOrco主要在成虫触角中表达，在不同发育阶段的成虫期表达量最高。与未注射的对照相比，注射GmolOrco 双链 RNA (dsRNA) 的雄性中GmolOrco 的表达降低至 39.92%，雌性中的GmolOrco表达降低至 40.43%。EAG 分析表明，注射 GmolOrco-dsRNA 的雄性对性信息素 ( Z)-8-十二碳烯乙酸酯 ( Z 8-12:OAc) 和 ( Z )-8-十二碳烯醇 ( Z 8-12:OH) 显着降低，且注射 GmolOrco-dsRNA 的雌性对绿叶挥发物 ( Z ) -3-乙酸己烯酯也显着下降。我们推断 Orco 介导的嗅觉在雄性和雌性G.moleta成虫中不同，主要参与识别雌性飞蛾释放的性信息素。