Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China.
Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China.
Pestic Biochem Physiol. 2024 Aug;203:105968. doi: 10.1016/j.pestbp.2024.105968. Epub 2024 May 29.
Insects rely primarily on a robust and precise olfactory recognition system to detect chemicals and environmental signals. Olfaction is mediated mainly by various odorant receptors (ORs) expressed on olfactory neurons. The odorant co-receptor (Orco) is a highly conserved and obligatory subunit of ORs, and its combination with conventional ORs to form ligand-gated ion channel heterodimeric complexes plays a crucial role in odor recognition. Anoplophora glabripennis Is a major quarantinable pest that affects broadleaved tree species worldwide. Odorant binding proteins (OBPs) and ORs have been identified in the A. glabripennis genome and the binding properties of some OBPs and their cognate ligands have been clarified. The role of the OR-mediated recognition pathway, however, remains largely uncharacterized. Here, we cloned and sequenced the full-length Orco gene sequence of A. glabripennis and performed structural characterization of the protein. We found that AglaOrco has high sequence homology with Orco from other orders of insects, and that it is highly conserved. Spatio-temporal differential expression analysis revealed that AglaOrco is highly expressed in adult antennae, and that expression at the sexually mature stage is significantly higher than at other developmental stages. There was no significant difference in expression between sexes. Silence AglaOrco using RNAi revealed that expression levels of AglaOrco mRNA fell significantly in both males and females at 72 h post-injection of 5 μg of dsOrco, with no obvious effect on expression of most other olfactory-related genes; however, some were up-or downregulated. For example, silenced Orco-expressing males and females showed a significant reduction in antennal potential responses to the odorants 3-carene, Ocimene, and 4-heptyloxy-1-butanol. Overall, the data suggest that AglaOrco plays an important role in mediating olfactory perception in A. glabripennis, and also identifies potential target genes for environmentally friendly pest control strategies.
昆虫主要依赖强大而精确的嗅觉识别系统来检测化学物质和环境信号。嗅觉主要由表达在嗅觉神经元上的各种气味受体（ORs）介导。气味共受体（Orco）是 ORs 的一个高度保守且必需的亚基，其与常规 ORs 结合形成配体门控离子通道异二聚体复合物，在气味识别中发挥关键作用。光肩星天牛是一种影响全球阔叶树种的主要检疫性害虫。已在光肩星天牛基因组中鉴定出气味结合蛋白（OBPs）和 ORs，并且阐明了一些 OBPs 及其同源配体的结合特性。然而，OR 介导的识别途径的作用在很大程度上仍未得到阐明。在这里，我们克隆并测序了光肩星天牛的全长 Orco 基因序列，并对该蛋白进行了结构特征分析。我们发现 AglaOrco 与其他目昆虫的 Orco 具有很高的序列同源性，并且高度保守。时空差异表达分析表明，AglaOrco 在成虫触角中高度表达，在性成熟阶段的表达显著高于其他发育阶段。雌雄之间的表达没有显著差异。使用 RNAi 沉默 AglaOrco 发现，在 5μg dsOrco 注射后 72 h，雄性和雌性 AglaOrco mRNA 的表达水平均显著下降，而大多数其他嗅觉相关基因的表达没有明显影响；然而，有些基因的表达被上调或下调。例如，沉默 Orco 表达的雄性和雌性对 3-蒈烯、罗勒烯和 4-庚氧基-1-丁醇等气味的触角电位反应明显减少。总体而言，数据表明 AglaOrco 在介导光肩星天牛的嗅觉感知中发挥重要作用，并确定了用于环保型害虫防治策略的潜在靶标基因。
