Brajon Ludvine, Comte Arthur, Capoduro Rémi, Meslin Camille, Antony Binu, Al-Saleh Mohammed Ali, Pain Arnab, Jacquin-Joly Emmanuelle, Montagné Nicolas
INRAE, Sorbonne Université, CNRS, IRD, UPEC, Université Paris Cité, Institute of Ecology and Environmental Sciences of Paris (iEES-Paris), Versailles and Paris, France.
King Saud University, Chair of Date Palm Research, Center for Chemical Ecology and Functional Genomics, Department of Plant Protection, College of Food and Agricultural Sciences, Riyadh 11451, Saudi Arabia.
Curr Res Insect Sci. 2024 Jul 17;6:100090. doi: 10.1016/j.cris.2024.100090. eCollection 2024.
The evolution of chemosensory receptors is key for the adaptation of animals to their environment. Recent knowledge acquired on the tri-dimensional structure of insect odorant receptors makes it possible to study the link between modifications in the receptor structure and evolution of response spectra in more depth. We investigated this question in palm weevils, several species of which are well-known invasive pests of ornamental or cultivated palm trees worldwide. These insects use aggregation pheromones to gather on their host plants for feeding and reproduction. An odorant receptor detecting the aggregation pheromone components was characterised in the Asian palm weevil This study compared the response spectra of this receptor, OR1, and its ortholog in the American palm weevil OR1. Sequences of these two receptors exhibit more than 70 amino acid differences, but modelling of their 3D structures revealed that their putative binding pockets differ by only three amino acids, suggesting possible tuning conservation. Further functional characterization of OR1 confirmed this hypothesis, as OR1 and OR1 exhibited highly similar responses to coleopteran aggregation pheromones and chemically related molecules. Notably, we showed that pheromone compounds strongly activated OR1, but we did not evidence any response to the pheromone compound rhynchophorol. Moreover, we discovered that several host plant volatiles also activated both pheromone receptors, although with lower sensitivity. This study not only reveals evolutionary conservation of odorant receptor tuning across the two palm weevil species, but also questions the specificity of pheromone detection usually observed in insects.
化学感应受体的进化是动物适应环境的关键。最近在昆虫气味受体三维结构方面获得的知识，使得更深入地研究受体结构变化与反应谱进化之间的联系成为可能。我们在棕榈象鼻虫中研究了这个问题，其中几种是世界范围内著名的观赏或栽培棕榈树的入侵害虫。这些昆虫利用聚集信息素来聚集在寄主植物上觅食和繁殖。在亚洲棕榈象鼻虫中鉴定出一种检测聚集信息素成分的气味受体。本研究比较了该受体（OR1）及其在美国棕榈象鼻虫中的直系同源物OR1的反应谱。这两种受体的序列表现出70多个氨基酸差异，但对其三维结构的建模显示，它们假定的结合口袋仅相差三个氨基酸，这表明可能存在调谐保守性。对OR1的进一步功能表征证实了这一假设，因为OR1和OR1对鞘翅目聚集信息素和化学相关分子表现出高度相似的反应。值得注意的是，我们发现信息素化合物强烈激活OR1，但未证明其对信息素化合物棕榈象甲酚有任何反应。此外，我们发现几种寄主植物挥发物也能激活这两种信息素受体，尽管敏感性较低。这项研究不仅揭示了两种棕榈象鼻虫物种间气味受体调谐的进化保守性，也对昆虫中通常观察到的信息素检测特异性提出了质疑。
