哌啶酸在丽蝇蛹集金小蜂滞育中的生物功能及其积累机制研究

The ectoparasitoid wasp Nasonia vitripennis is an excellent parasitic natural enemy insect, and it is capable of entering a facultative, final-instar larval diapause. Diapause can enhance cold tolerance significantly for overwintering insects, and this feature is particularly attractive for resolving bottleneck questions in biological control industry, including shelf-life, shipment and establishment of natural enemy insects. Our recent results indicate that the ectoparasitoid wasp can dramatically accumulate pipecolic acid (elevated 160 times) during larval diapause. Pipecolic acid exert a profound impact on growth, development, stress resistance and many other features of organisms, but little effort has focused on the biological function and metabolic mechanism of pipecolic acid in insects. We hypothesize that pipecolic acid may serve as a potential cryoprotectant confer increased cold hardiness, or it may be involved in regulation of developmental arrest during diapause in the parasitoid wasp. This proposal builds on these initial observations to evaluate the contributions of pipecolic acid to diapause and cold tolerance. Techniques of insect comparative physiology, transcriptomics, GC-MS/LC-MS and RNAi are employed to analyze the effect of exogenous pipecolic acid on development and stress resistance of Nasonia vitripennis and to disentangle mechanism of pipecolic acid accumulation during diapause in the parasitoid wasp. As well as the function of pipecolic acid during diapause and cold tolerance, the signal factors and signaling transduction pathways that involved in metabolic regulation of pipecolic acid will be identified. The functional mechanism of this amino acid will also be explored. Our program could provide references for uncovering molecular mechanisms of diapause and cold tolerance in parasitoids, and could also suggest techniques that may be exploited to increase application efficiency of parasitoid wasps in biological control industry.

丽蝇蛹集金小蜂是优良的寄生性天敌昆虫，为兼性末龄幼虫滞育。滞育能显著提高越冬昆虫的耐寒性，该特性对解决寄生蜂等天敌昆虫产品的贮存、运输和定殖等瓶颈问题具有重要意义。前期研究测试到该蜂滞育幼虫极显著积累哌啶酸（提高160倍）。哌啶酸对许多生物的生长发育、抗逆性等具有重要作用，但在昆虫中的生物功能和代谢调控机制等尚不明确。我们推测哌啶酸可能作为低温保护物质提高寄生蜂的耐寒性，或参与调节寄生蜂的生长发育抑制等。本项目拟在前期研究的基础上，利用昆虫比较生理学、转录组学、GC-MS/LC-MS、RNAi等技术，分析外源哌啶酸对丽蝇蛹集金小蜂生长发育和抗逆性的影响，探明滞育丽蝇蛹集金小蜂的哌啶酸积累机制，剖析哌啶酸在滞育和耐寒性中的生物功能，鉴定参与哌啶酸代谢调控的信号因子及信号转导通路，探讨哌啶酸的作用机制，为揭示寄生蜂滞育相关耐寒性的分子机制提供参考依据，也为提高寄生蜂的应用潜能提供技术支撑。

丽蝇蛹集金小蜂是优良的寄生性天敌昆虫，为兼性末龄幼虫滞育。滞育能显著提高越冬昆虫的耐寒性，该特性对解决寄生蜂等天敌昆虫产品的贮存、运输和定殖等瓶颈问题具有重要意义。前期研究发现该蜂滞育幼虫极显著积累哌啶酸，哌啶酸对许多生物的生长发育、抗逆性等具有重要作用，但在昆虫中的生物功能和代谢调控机制等尚不明确。本项目通过利用昆虫比较生物学、生理学、转录组学等技术，从生物学、生理学和分子水平上证明了外源添加哌啶酸对丽蝇蛹集金小蜂生长发育具一定抑制作用，可显著提高其耐寒性，明确了哌啶酸的功能，掌握了调控寄生蜂耐寒性的新方法；比较了外源哌啶酸及滞育状态引起的金小蜂转录组差异，鉴定了金小蜂滞育关联基因及哌啶酸调控相关基因，分析了直接参与哌啶酸积累调控的5个关键基因，3个重要信号转导途径包括mTOR、MAPK/ERK及PI3K/AKT信号通路及相关信号因子；获得了哌啶酸代谢调控基因lkr/sdh和p5cr，并明确了其基因表达规律和功能，初步确定了哌啶酸积累的代谢途径和关键调控酶，为深入揭示哌啶酸的功能和积累调控机制奠定了基础。在以上研究基础上，提出了利用滞育诱导和外源添加哌啶酸提高金小蜂耐寒性的方法，以延长金小蜂等天敌昆虫的贮存时间，促进天敌昆虫的规模化生产和应用。此外，这些研究结果为继续开展滞育昆虫的氨基酸感应和代谢调控分子机制、耐寒机理等提供了方法参考和理论依据，有助于深入解析昆虫滞育的分子机理。