参与飞蝗口器触须识别植物挥发物的气味分子受体及其协同作用机制

Food selection is crucial for the survival of herbivorous insects because feeding is the energe source of insect development and reproduction. The antennae and mouthparts are both important in the insects’ food selections. Currently, many studies on olfaction molecular mechanisms have been reported. But most of them were about the functional analysis with one gene, very few focused on the integrated roles of multi-odorant receptors in sensation to the volatiles of the plants. Here, we propose to explore the integrated olfaction molecular mechanisms of locust mouthpart palps in sensation the odors of plants. Firstly, performing the combination of GC-EAD, GC-MS, single sensillum recording (SSR), palp opening response (POR), and behavioral assays to identify the featured odors of plants, including wheat, maize, cotton and soybean, which sensed by locust mouthpart palps. Secondly, using transcriptome sequencing, in situ hybridization, and SSR to identify odorant receptors in mouthparts, to characterize the functional types of sensilla basiconica on mouthpart palps, and to localize the ORs in the functional types of sensilla. Subsequently, using Drosophila ‘empty neuron’ expression system to determine the response spectrums of each OR. Finally, examination of electrophysiological responses of single sensillum, POR, and behavior of locusts when each or multi-ORs to be depressed by RNAi. This study will be helpful to understand integrated olfaction molecular mechanisms of food selection in herbivorous insects.

植食性昆虫通过取食保证其生长发育和繁殖的能量来源。昆虫的触角和口器在其食物选择中发挥决定性作用，已有大量关于昆虫触角和口器嗅觉分子机制的研究，但多针对单个基因功能，尚无关于昆虫多个气味分子受体协同识别植物的报道。本项目拟以飞蝗为研究对象，采用GC-EAD、质谱分析、单感器记录技术、触须张合反应和行为反应测定技术明确飞蝗触须识别小麦、玉米、棉花和大豆所用的特征气味。利用转录组测序技术、原位杂交技术、转基因技术、单感器记录等，鉴定口器触须气味分子受体、确定锥形感器功能型、明确相关气味分子受体的定位以及气味分子受体在转基因果蝇空神经元中的感受气味谱。之后，利用RNAi技术敲降单个和多个气味分子受体基因后，测定神经元的电生理反应、触须张合反应和飞蝗行为反应等，以期探讨飞蝗口器触须表达的气味分子受体协同感受某种植物的机制。本项目的研究成果将会丰富植食性昆虫识别植物的嗅觉分子机制。

选择适合的植物作为食物对于植食性昆虫生长发育和繁殖所需的能量至关重要。植物释放的挥发物信号在植食性昆虫寻找食物过程中发挥了重要作用。通常植物的多种挥发物组合式地构成植物的特征化学信息而被昆虫特异感受识别。植食性昆虫是如何运用其化学感受能力识别并区分寄主与非寄主植物，一直是需要破解的科学问题。目前关于昆虫嗅觉分子机制的研究多是针对单个气味分子受体感受气味分子机制的研究，很少有针对植食性昆虫的多个气味分子协同感受某种植物整体气味的相关研究。我们提出存在植食性昆虫感受植物特征气味分子的多个气味分子受体协同作用和模式。为解决该问题，本项目以飞蝗为研究对象，采用转录组测序、气相色谱-质谱联用分析、单感器记录技术、触须张合反应(POR)、RNA原位杂交、神经元原位示踪、基因表达调控技术和行为测定技术，解析了飞蝗在不同距离内趋向/驱避植物挥发物的嗅觉感受机制，鉴定出了飞蝗触角和触须感受植物的特征气味；明确了能够诱发飞蝗产生呕吐反应的气味分子谱，深入探讨了相关的嗅觉分子机制和神经通路；明确了参与飞蝗触须识别寄主植物与非寄主植物挥发物的6个嗅觉受体，提出了一个植食性昆虫感受植物特征气味分子的多个气味分子受体的协同作用模式。研究成果加深了对植食性昆虫-植物互作的分子机制理解。