苹果蠹蛾颗粒体病毒对干旱、强日照胁迫的响应机制研究

This proposal is focused on the mecanism of how CypoGV isolated from Xinjiang response the extreme environmental stress: heavy sunlight radiation and drought, which generally be concerned as harmful factors to microorganisms. The proposal was carried out by comparing two CypoGV isolates, CypoGV-KS-1 as extreme condition adapted isolate and CypoGV-BG as an sensitive isolate by the approaches of field assay, humidy assay, sunlight and UV radiation assay, key genes contributed to their resistance to extreme environmental stress, the physiological structure of virus, and virus-host insect co-DGE analysis. The origin of the virus resistance to drought and heavy sunlight radiation would be revealed by the comparison of two different isolates on the virulence decreasing in the filed under such disadvantage environmental stress, the relationship between virus variation and environmental stress, the relationship of virus physiological structure and resistance to environmental stress, and the coevolution of virus and its host insect. The mechanism of how CypoGV response to the stress of drought and heavy sunlight is possibly the answer of the origin of the virus resistance to such stress. The expected results also could shed a light on the study that explain the mechanisms of how microorganisms response the extreme environmental stress, even for other arthropod pathogens.

病原微生物对干燥、强光照环境通常缺乏抵御能力，但我国重要入侵生物苹果蠹蛾的病原微生物CypoGV却能够克服这种极端环境胁迫，但其机理不明。项目选择分离自我国新疆干旱、强日照环境的苹果蠹蛾颗粒体病毒喀什株（CypoGV-KS1）和对极端环境非常敏感的比利时株（CypoGV-BG）为研究材料，通过田间生测、湿度实验、日光与紫外辐照实验、病毒抗逆性基因筛选与功能验证、病毒抗逆性生理结构分析、病毒与宿主基因组DGE表达谱分析等手段，对比研究二者在新疆极端环境条件下的田间毒力衰减规律、病毒生理结构和遗传变异特征、病毒与宿主昆虫协同进化，从病毒生理结构、基因组变异、与宿主昆虫的协同作用角度了解CypoGV喀什株对干旱、强光照胁迫的响应过程，旨在阐明CypoGV对极端环境胁迫的响应机制。预期研究结果将为深入研究节肢动物病原微生物对极端环境的适应性进化提供重要的科学数据。

昆虫病毒在非常极端的环境条件下依然能够侵染宿主昆虫导致虫瘟病的流行，例如强光照、高温干旱等。苹果蠹蛾颗粒体病毒在新疆和河西走廊地区对苹果蠹蛾具有很好的控制效果，但其作为微生物，是如何适应强日照紫外线辐射和高温等一般微生物不能抵御的极端环境的，目前并不知晓。本项目研究通过对CpGV病毒形态结构、包涵体蛋白表达水平与基因组序列差异与响应极端环境胁迫的相关性的系统研究，已经明确了病毒自身变异响应极端环境胁迫的机制之一，是提高了granulin基因表达水平、获得加厚加长的病毒包涵体结构。并从病毒毒力差异与基因组结构、特征序列变化，初步解释了CpGV与宿主昆虫协同响应极端环境胁迫的分子机制；特别是pe38、odv-e66中特征序列的缺失和特征序列插入对于病毒适应极端环境或克服抗性种群对病毒的抗性发挥重要作用，这些基因的变异揭示了病毒在与宿主昆虫的协同进化中是如何通过遗传变异突破宿主抗性、或适应极端外界环境的。研究结果对于丰富杆状病毒分子生物学和解释微生物对极端环境的适应性提供了非常重要的基础科学数据。