Li Xinghao, Hu Fangjing, Li Rufan, Peng Danhao, Gao Ping, Rao Fuqiang, Li Yonghong, Liu Deguang
Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, College of Plant Protection, Northwest A&F University, Yangling 712100, Shaanxi, China.
Hybrid Rapeseed Research Center of Shaanxi Province, Yangling 712100, Shaanxi, China.
Pestic Biochem Physiol. 2025 Nov;214:106578. doi: 10.1016/j.pestbp.2025.106578. Epub 2025 Jul 15.
The olfactory system of insects plays a vital role in their survival by enabling them to detect chemical cues and adapt to changing environments. The rape stem weevil, Ceutorhynchus asper, is a significant pest posing a challenge for rapeseed production due to its destructive feeding habit and increasing resistance to insecticides. So far, there's still limited knowledge about structure and function of odorant binding proteins (OBPs) in beetles like C. asper. In this study, we identified and expressed CaspOBP12, a highly expressed OBP in antennae of C. asper with female-biased expression. Phylogenetic analyses of OBPs from Curculionidae showed that CaspOBP12 and its homologs fell into a distinct and conservative clade, likely involved in the evolutionary radiation of the Curculionidae. CaspOBP12 exhibited a broad-spectrum binding pattern. CaspOBP12 demonstrated good binding affinities for host plant volatiles, such as benzyl isothiocyanate (ITC) (Ki = 10.44 μM) and decanal (Ki = 9.94 μM), and the pesticide λ-cyhalothrin (Ki = 7.41 μM), suggesting its multiple roles in perception of host volatiles and insecticides. The beetle exhibited strong electrophysiological responses to benzyl ITC and decanal, and further behavioral experiments demonstrated that both volatiles were strongly attractive to C. asper. Molecular docking and dynamics simulations identified candidate key residues (i.e., VAL42, VAL83 and PHE104) in ligand binding of CaspOBP12. Site-directed mutagenesis experiments targeting these residues significantly reduced the mutant proteins' binding affinities, with no binding with λ-cyhalothrin or decanal observed for the mutant protein at PHE104. Our study highlight interactions of the conserved CaspOBP12 and its homologs with variable plant volatiles and insecticides, suggesting their multiple functional roles in chemical senses and insecticide resistance development. This study can also enhance our understanding of the olfactory mechanisms of C. asper, and provide a basis for the development of novel environment-friendly control techniques.
昆虫的嗅觉系统通过使它们能够检测化学信号并适应不断变化的环境，在其生存中发挥着至关重要的作用。油菜茎象甲（Ceutorhynchus asper）是一种重要害虫，因其具有破坏性的取食习性以及对杀虫剂的抗性不断增强，给油菜籽生产带来了挑战。到目前为止，对于像油菜茎象甲这样的甲虫中气味结合蛋白（OBPs）的结构和功能，人们的了解仍然有限。在本研究中，我们鉴定并表达了CaspOBP12，它是油菜茎象甲触角中高表达且具有雌性偏向性表达的一种OBP。对象甲科OBPs的系统发育分析表明，CaspOBP12及其同源物属于一个独特且保守的分支，可能参与了象甲科的进化辐射。CaspOBP12表现出广谱的结合模式。CaspOBP12对寄主植物挥发物，如异硫氰酸苄酯（ITC）（解离常数Ki = 10.44 μM）和癸醛（Ki = 9.94 μM），以及农药氯氟氰菊酯（Ki = 7.41 μM）都表现出良好的结合亲和力，这表明它在感知寄主挥发物和杀虫剂方面具有多种作用。这种甲虫对异硫氰酸苄酯和癸醛表现出强烈的电生理反应，进一步的行为实验表明这两种挥发物都对油菜茎象甲具有很强的吸引力。分子对接和动力学模拟确定了CaspOBP12配体结合中的候选关键残基（即VAL42、VAL83和PHE104）。针对这些残基的定点突变实验显著降低了突变蛋白的结合亲和力，对于PHE104位点的突变蛋白，未观察到其与氯氟氰菊酯或癸醛的结合。我们的研究突出了保守的CaspOBP12及其同源物与可变的植物挥发物和杀虫剂之间的相互作用，表明它们在化学感知和抗杀虫剂性发展中具有多种功能作用。本研究还可以增进我们对油菜茎象甲嗅觉机制的理解，并为开发新型环境友好型控制技术提供依据。
