中红侧沟茧蜂嗅觉受体MmedOr2基因的克隆及组织表达谱

Cloning and Tissue Expression Analysis of an Olfactory Receptor MmedOr2 in Microplitis mediator(Hymenoptera:Braconidae)

嗅觉在天敌昆虫寻找寄主、躲避敌害、交配、转移等行为中发挥关键作用。嗅觉受体是昆虫嗅觉系统中一类重要的功能蛋白。本文选取从中红侧沟茧蜂触角cDNA文库鉴定一个嗅觉受体基因MmedOr2序列片段,采用RACE技术克隆获得中红侧沟茧蜂嗅觉受体基因MmedOr2的全长序列。通过实时荧光定量PCR解析了该基因在中红侧沟茧蜂不同发育阶段、不同组织部位以及交配前后的转录表达谱。结果表明,MmedOr2在触角中特异性表达,且在雌蜂触角中表达量显著高于雄蜂触角。雌、雄蜂羽化后分别在第3 d和第4 d MmedOr2表达量达到最高,该基因转录表达量达到最高后逐渐下降。另外,交配后雌蜂MmedOr2表达量显著下降。根据以上研究结果,我们推测MmedOr2可能是性信息素受体,在中红侧沟茧蜂寻找配偶等行为中发挥功能。

Olfaction plays a vital role in host-seeking, enemy-defending, mating and immigration in natural enemies. Olfactory receptors are an important class of functional proteins in insect olfactory system. In this study, a sequence fragment of olfactory receptor gene MmedOr2 in Microplitis mediator was identified from the antenna cDNA library, and the full-length sequence of this gene was obtained by using rapid amplification of cDNA ends （RACE）. Further, expression profiles of this gene in different tissues along the developmental stages, as well as before and after mating was analyzed using real-time quantitative PCR. It was found that the receptor gene was specifically expressed in antenna, and expression level was significantly higher in female than in male. In female, MmedOr2 expression reached the highest level on the 3rd day after emergence while the highest expression in male appeared on the 4th day after emergence. After peak expression, MmedOr2 expression level declined gradually in both male and female adults. In addition, expression level of MmedOr2 in female adults was notably decreased after mating. According to above findings, we speculate that MmedOr2 may be a sex pheromone receptor and plays an important role in mate-searching.