Sun Liang, Wang Qian, Wang Qi, Dong Kun, Xiao Yong, Zhang Yong-Jun
Key Laboratory of Tea Quality and Safety Control, Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, China.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Physiol. 2017 Sep 26;8:735. doi: 10.3389/fphys.2017.00735. eCollection 2017.
The chemosensory system is essential for insects to detect exogenous compounds, and odorant binding proteins (OBPs) play crucial roles in odorant binding and transduction. In the alfalfa plant bug , an important pest of multiple crops, our understanding of the physiological roles of antenna-biased OBPs has increased dramatically, whereas OBPs related to gustation have remained mostly unexplored. In this study, we employed RNA sequencing and RACE PCR methods to identify putative OBPs from the adult forelegs of both sexes. Eight candidate OBPs were identified, and three OBPs (AlinOBP15, 16, and 17) were novel. Full-length sequence alignment and phylogenetic analyses suggested that these three candidate OBPs had characteristics typical of the insect OBP family. AlinOBP16 and 17 displayed six highly conserved cysteines, placing them in the classic OBP subfamily, whereas AlinOBP15 resembled AlinOBP14 and clustered with the Plus-C clade. Quantitative real-time PCR (qRT-PCR) revealed distinct and significant tissue- and sex-biased expression patterns. was highly expressed in female heads, and and were strongly expressed in female antennae. In particular, , the most abundant OBP gene in our foreleg transcriptome dataset, was predominately expressed in adult legs. Furthermore, four types of sensilla hairs were observed on the forelegs of adult , including sensilla trichodea, setae, and two types of sensilla chaetica (Sch1 and Sch2). Anti-AlinOBP11 antiserum strongly labeled the outer sensillum lymph of Sch2, implying that it has important gustatory functions in . Our current findings provide evidence that OBPs can be functionally expressed in the tarsal gustatory sensilla of hemipteran mirid species, broadening our understanding of OBP chemosensory function in insects and facilitating the discovery of new functional targets for the regulation of insect host-searching behaviors.
化学感应系统对于昆虫检测外源化合物至关重要，而气味结合蛋白（OBPs）在气味结合和转导中起关键作用。在多种作物的重要害虫苜蓿盲蝽中，我们对触角偏向性OBPs的生理作用的了解有了显著增加，而与味觉相关的OBPs大多仍未被探索。在本研究中，我们采用RNA测序和RACE PCR方法从成年雌雄两性的前腿中鉴定推定的OBPs。鉴定出了8个候选OBPs，其中3个OBPs（AlinOBP15、16和17）是新的。全长序列比对和系统发育分析表明，这3个候选OBPs具有昆虫OBP家族的典型特征。AlinOBP16和17显示出6个高度保守的半胱氨酸，使其属于经典OBP亚家族，而AlinOBP15与AlinOBP14相似，并与Plus-C进化枝聚类。实时定量PCR（qRT-PCR）揭示了明显且显著的组织和性别偏向性表达模式。 在雌性头部高度表达， 和 在雌性触角中强烈表达。特别是， 是我们前腿转录组数据集中最丰富的OBP基因，主要在成年腿部表达。此外，在成年苜蓿盲蝽的前腿上观察到4种类型的感器毛，包括毛形感器、刚毛，以及两种类型的刺形感器（Sch1和Sch2）。抗AlinOBP11抗血清强烈标记Sch2的外部感器淋巴，这意味着它在苜蓿盲蝽中具有重要的味觉功能。我们目前的研究结果提供了证据，表明OBPs可以在半翅目盲蝽科昆虫的跗节味觉感器中功能性表达，拓宽了我们对昆虫OBP化学感应功能的理解，并有助于发现调控昆虫寄主搜索行为的新功能靶点。
