Odorant Receptors for Detecting Flowering Plant Cues Are Functionally Conserved across Moths and Butterflies
Mengbo Guo, Lixiao Du, Qiuyan Chen, Yilu Feng, Jin Zhang, Xiaxuan Zhang, Ke Tian, Song Cao, Tianyu Huang, Emmanuelle Jacquin-Joly, Guirong Wang, Yang Liu
近日，中国农业科学院植物保护研究所（以下简称植保所）生物杀虫剂创制与应用创新团队系统解析了重大农业害虫棉铃虫气味受体基因家族的功能，揭示了鳞翅目昆虫通过嗅觉与被子植物协同进化的新机制。这一研究加深了人们对昆虫与植物协同进化的认识，以这类关键的嗅觉受体为靶标可以发展环境友好的害虫行为调控绿色防控技术。相关研究成果在线发表在《分子生物学与进化》上。
鳞翅目昆虫包括蛾子和蝴蝶两大类，是地球生态系统中最重要的生物类群之一。绝大多数鳞翅目昆虫的幼虫会危害各类农作物，而成虫多取食花蜜来补充营养。
植保所研究员王桂荣介绍，植物在生长过程中会释放复杂的植物挥发物，而在与植物的共进化过程中，鳞翅目昆虫也形成了高度灵敏特异的嗅觉系统来识别各类植物挥发物，从而寻找到寄主植物并完成取食、产卵等行为。对于植食性昆虫如何识别寄主挥发物的分子机理却知之甚少。
该研究对重大农业害虫棉铃虫的气味受体基因家族的功能进行了系统研究，绘制了棉铃虫气味受体家族编码寄主植物挥发物的功能图谱，揭示了棉铃虫气味受体通过组合编码的方式识别复杂的寄主挥发物，回答了为什么鳞翅目害虫只有几十个气味受体却能编码成千上万种气味分子的疑问。在此基础上进一步发现识别寄主植物花香气味的受体在鳞翅目昆虫中高度保守。该受体的出现伴随鳞翅目昆虫管状喙的产生，与被子植物的暴发时间一致。
该研究得到国家自然科学基金、中国农科院科技创新工程等项目资助。
来源：中国科学报 张晴丹 欧阳灿彬
Abstract
Odorant receptors (ORs) are essential for plant–insect interactions. However, despite the global impacts of Lepidoptera (moths and butterflies) as major herbivores and pollinators, little functional data are available about Lepidoptera ORs involved in plant-volatile detection. Here, we initially characterized the plant-volatile-sensing function(s) of 44 ORs from the cotton bollworm Helicoverpa armigera, and subsequently conducted a large-scale comparative analysis that establishes how most orthologous ORs have functionally diverged among closely related species whereas some rare ORs are functionally conserved. Specifically, our systematic analysis of H. armigera ORs cataloged the wide functional scope of the H. armigera OR repertoire, and also showed that HarmOR42 and its Spodoptera littoralis ortholog are functionally conserved. Pursuing this, we characterized the HarmOR42-orthologous ORs from 11 species across the Glossata suborder and confirmed the HarmOR42 orthologs form a unique OR lineage that has undergone strong purifying selection in Glossata species and whose members are tuned with strong specificity to phenylacetaldehyde, a floral scent component common to most angiosperms. In vivo studies via HarmOR42 knockout support that HarmOR42-related ORs are essential for host-detection by sensing phenylacetaldehyde. Our work also supports that these ORs coevolved with the tube-like proboscis, and has maintained functional stability throughout the long-term coexistence of Lepidoptera with angiosperms. Thus, beyond providing a rich empirical resource for delineating the precise functions of H. armigera ORs, our results enable a comparative analysis of insect ORs that have apparently facilitated and currently sustain the intimate adaptations and ecological interactions among nectar feeding insects and flowering plants.
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