滞育激素基因调控桃小食心虫滞育行为的分子机制

Diapause is a genetically programmed developmental arrest accompanied by a major decline in metabolic activity. Diapause has evolved as an adaption for surviving seasonally recurring adverse environments and allows the synchronization of life cycle with favorable periods. Depending on the species, diapause can occur at any developmental stage, and in some insects the diapause hormone (DH) has been shown to play a pivotal role in diapause regulation. Low diapause induction temperature and short photoperiod play important role in diapause physiology of in the peach fruit moth pest, Carposina sasakii Matsumura. However molecular mechanism of the DH of C. sasakii fluctuating winter and spring conditions is generally poorly known. First, DH of C. sasakii will be cloned in this subject, contrast DH gene expressing differences in diapause and non-diapause C. sasakii using Q-PCR, figure out regulate mechanisms of DH induces diapause and breaks diapause in C. sasakii. Second, in order to verify gene function of the DH of C. sasakii, technology of exogenous diapause hormone injection and RNAi will be used further, mechanism of molecular regulation of the DH of C. sasakii in consequence of diapause induce to diapause break at last. This project will benefit forecast and management technology for C. sasakii in neuropeptide hormone application．

滞育激素在滞育行为调控方面起关键作用，研究滞育激素的分子结构和作用机制，可以为害虫防治提供理论和实验依据。关于桃小食心虫的滞育研究，前人已证实低温结合短光照可诱导其滞育，而高温结合一定的长光照则抑制其滞育的发生，但其滞育激素作用的分子机理尚不清楚。本项目拟首先克隆桃小食心虫的滞育激素基因，以滞育和非滞育两种类型的个体互为对照，利用Q-PCR技术解析滞育激素基因在桃小食心虫整个发育期的表达模式，推测该基因调控桃小食心虫滞育可能的作用机制；然后利用RNA干扰技术、外源滞育激素注射虫体后的活性分析等方法对该基因的分子功能进行验证，揭示滞育激素在桃小食心虫滞育诱导及滞育解除过程中调控的分子机理，以期为桃小食心虫的精准测报、以及新型治理技术的开发提供科学依据。

桃小食心虫EF-1a、ACT和GAPDH是用作qPCR基因表达研究使用的合适内参基因。克隆获得了桃小食心虫DH基因及其受体基因DH receptor（DHr），DH基因表达部位是咽下神经节，DHr在体壁、头部表达量较高。CaDH基因在生活史的每一个虫态都有表达，成虫中表达量高，老龄幼虫和老熟幼虫表达量低，蛹期表达量较高；进入圆茧初期表达量有明显上升，滞育过程维持一定的表达量。光周期是诱导桃小食心虫幼虫形成滞育的关键因子，长光照和短光照两种条件下幼虫CaDH基因表达模式没有差别，CaDHr基因表达量与CaDH表达基本同步变化。该基因在桃小食心虫滞育中可能的作用机制是与基础的生理代谢调节相关，当代谢旺盛需要大量合成新组织的时期该基因表达量高。同时，即使在滞育期间，该基因表达依然维持一定的量，说明DH基因可能调控维持一些基本的生理代谢。CaDH基因在桃小食心虫生长发育过程中调控的代谢贯穿整个生命周期，表达与否并不直接决定滞育的形成。