基于组学探究光周期诱导美国白蛾蛹滞育的分子机理

Diapause is an ecological adaptation response in insects to cope with adverse environments. Knowledge regarding molecular mechanism of diapause is helpful to understand the signal recognition and interaction between insects and environment, and further is useful for control of pests and utilization of natural enemies. The fall webworm, Hyphantria cunea (Drury) is an important invasive pest in China. The diapause of this insect pest is mainly induced by photoperiod. Differring from other pests diapausing in pupal stage, such as Helicoverpa armigera, the photosensitive phase of H. cunea is early instar larva. However, until to now, reports on the molecular mechanism associated with pupal diapause induced by photoperiod in H. cunea is very few. In this study, to explore molecular mechanism of pupal diapause in H. cunea, mRNA, protein and metabolite levels across non-diapause (regular development) and diapause individuals induced by photoperiod in different stages will be analysed using transcriptomics, proteomics and metabolomics. Key regulatory genes and related pathways will be identified based on the “-omics” data. Then, the function of some important regulatory gene will be evaluated using RNA interference (RNAi) and quantitative PCR (qPCR). Findings in this study will provide important clues for understanding the molecular mechanism underlying diapause induced by photoperiod in lepidoptera pests. Furthermore, the data obtained in the study is also useful to regulate the population quantity of H.cunea in overwintering generation in the future.

滞育是昆虫应对不利环境的一种生态适应行为，研究其机理有助于揭示昆虫与环境信号之间的识别与响应机制，认知这种机制对有效控制害虫和利用天敌具有重要价值。美国白蛾是我国重大入侵害虫，主要受光周期信号调控产生滞育。与棉铃虫等蛹滞育的昆虫不同，美国白蛾蛹滞育受光周期诱导的敏感期为低龄幼虫，但关于其滞育发生及调控机理的研究目前尚未见报道。本项目以美国白蛾滞育和非滞育（正常发育）个体互为对照，通过对光周期诱导美国白蛾蛹滞育过程中的不同时间点进行全面的转录组学、蛋白质组学和代谢组学研究与分析，筛选和鉴定参与光周期诱导美国白蛾蛹滞育的关键调控基因和信号途径，并利用RNAi和qPCR等技术对关键基因的功能进行验证，阐明光周期诱导美国白蛾蛹滞育的分子机理。研究结果将为揭示鳞翅目害虫光周期诱导蛹滞育机理提供重要科学数据，也对今后利用滞育调控遏制美国白蛾越冬代害虫种群数量具有重要的现实意义。

本项目以美国白蛾为研究对象，研究了光周期对美国白蛾滞育的影响及其诱导蛹期滞育的分子机制。研究表明，美国白蛾属典型长日照发育-短日照滞育型昆虫，光周期在美国白蛾滞育诱导中发挥主导作用，温度伴随光周期发挥作用，低温和短光照利于滞育发生，临界光周期随着温度的升高逐渐缩短。美国白蛾对光周期诱导滞育的敏感龄期研究表明，美国白蛾对短光照诱导滞育具有累积效应，幼虫感受光周期最敏感阶段为3-5龄。通过对美国白蛾敏感龄期幼虫脑组织进行转录组学、蛋白质组学和代谢组学研究与分析，发现3龄时期是美国白蛾诱导滞育启动的关键时期，与光周期诱导滞育相关的基因主要包括生物钟基因、神经肽类激素基因和热激蛋白基因等，5-羟色胺和褪黑素是美国白蛾滞育过程中的重要调控物质。短光照诱导生物钟节律基因CLK下调表达以及5-羟色胺的积累，抑制了促前胸腺激素与其受体的结合，从而抑制了蜕皮素的合成与积累，导致美国白蛾蛹进入滞育状态。利用RNAi技术抑制美国白蛾CLK基因表达，可使长光照条件下的部分美国白蛾滞育，验证了该基因在美国白蛾蛹滞育过程的重要作用。此外，本项目还研究了细胞穿膜肽TAT与昆虫神经肽类激素的体外融合及表达技术，并对其在害虫治理中的应用进行了探索研究。上述研究结果为今后害虫治理提供新的思路与途径。