Pu Lin-Mei, Wang Peng-Fei, Lu Yu-Yue, Yang An-Jin, Liu Li-Li, Liu Nai-Yong
Key Laboratory of Forest Disaster Warning and Control of Yunnan Province, Southwest Forestry University, Kunming 650224, China.
College of Biological Science and Food Engineering, Southwest Forestry University, Kunming 650224, China.
Pestic Biochem Physiol. 2025 May;210:106371. doi: 10.1016/j.pestbp.2025.106371. Epub 2025 Mar 9.
Three sympatric Tomicus bark beetles, Tomicus yunnanensis, Tomicus brevipilosus and Tomicus minor that coexist in the trunks of a pine but occupy different spatiotemporal ecological niches, are the best-studied examples for addressing functional differentiation of chemosensory protein (CSP) orthologs. Here, totally 36 CSP-coding genes belonging to 12 groups of orthologs were identified from three Tomicus beetles. Tomicus CSP orthologs shared the high conservation and slight differences in sequence characteristics, phylogenetic relationships and tissue expression profiles. Binding assays revealed that 12 antenna-enriched Tomicus CSPs could respond strongly to non-host volatiles, pheromones and insecticides where each group of CSP orthologs presented diverse ligand-binding properties. CSP1 and CSP2 could interact strongly with benzaldehyde and salicylaldehyde (dissociation constant, K < 14 μM) whereas CSP10 and CSP11 preferred to bind 1-hexanol and acetophenone (K < 13 μM). All the proteins were tuned to chlorpyrifos with particularly high affinities (K < 10 μM). Two conserved residues (glutamine, Q64 and leucine, L72) of CSP11 orthologs contributed to the specific binding to optimal ligands, but exhibited opposite binding properties between chlorpyrifos and other four compounds. Our study sheds light on the functional conservation and divergence of Tomicus CSP orthologs in olfactory reception and insecticide resistance, implying the correlation between ecological niche differentiation and olfactory specialization in three Tomicus bar beetles.
三种同域分布的齿小蠹属小蠹虫，即云南齿小蠹、短毛齿小蠹和微小齿小蠹，共存于松树树干中，但占据不同的时空生态位，它们是研究化学感受蛋白（CSP）直系同源物功能分化的最佳实例。在此，从三种齿小蠹中总共鉴定出36个属于12个直系同源物组的CSP编码基因。齿小蠹CSP直系同源物在序列特征、系统发育关系和组织表达谱方面具有高度保守性和细微差异。结合试验表明，12种在触角中富集的齿小蠹CSP能够对非寄主挥发物、信息素和杀虫剂产生强烈反应，其中每组CSP直系同源物都呈现出不同的配体结合特性。CSP1和CSP2能与苯甲醛和水杨醛强烈相互作用（解离常数K < 14 μM），而CSP10和CSP11更倾向于结合1 - 己醇和苯乙酮（K < 13 μM）。所有蛋白质对毒死蜱都有特别高的亲和力（K < 10 μM）。CSP11直系同源物的两个保守残基（谷氨酰胺，Q64和亮氨酸，L72）有助于与最佳配体的特异性结合，但在毒死蜱和其他四种化合物之间表现出相反的结合特性。我们的研究揭示了齿小蠹CSP直系同源物在嗅觉接收和抗杀虫剂方面的功能保守性和差异性，这意味着三种齿小蠹的生态位分化与嗅觉特化之间存在关联。
