寄主植物对甜菜夜蛾核型多角体病毒感染宿主的影响及机理

The interactions between host plants and natural enemies are one of the focuses of biological control of insect pests, while the effect of host plants on the insect virus and the corresponding mechanism is scarcely explored. Based on the research results of domestic and foreign counterparts and on our previous work, this study will take three species of host plants (soybeans, collard and water spinach), beet armyworm and SeMNPV as research systems, measure the phenol content as well as the activities of peroxidase, chitinase, lectin and so on, and determine the correlation between these indicators of plants and the infectivity of SeMNPV to beet army worm. Some research methods will be applied such as insect immunology, physiology and molecular biology. On the basis of screening and cloning the functional genes of peritrophic membrane, phenoloxidase genes, cell apoptosis genes (caspase) and antimicrobial peptide genes (gloverin) which resist to SeMNPV infection, we will focus on the difference in both the expression of above functional genes and the structure of peritrophic membrane which might be induced by different host plants fed by SeMNPV-infected and uninfected beet armyworm. Through this study, we will determine the correlation between the susceptibility of beet armyworm feeding different host plants to SeMNPV and the chemical defensive substance of plants, the structure of peritrophic membrane of host insects, or the functional genes, and primarily determine the effect of host plants on SeMNPV infecting beet armyworm and revealed the corresponding mechanism. The expected results will not only contribute to deeply understanding the plant-insect-virus interactions in theory, but also provide basis for using insect virus to effectively control beet armyworm on different crops in practice.

寄主植物与天敌昆虫的互作是害虫生物防治的研究热点之一，但寄主植物对昆虫病原微生物的影响及机理还了解得很少。本研究以3种寄主植物（黄豆、甘蓝、蕹菜）、甜菜夜蛾和核型多角体病毒（SeMNPV）为研究系统，测定3种植物叶片中总酚含量和过氧化物酶、几丁质酶、凝集素等物质的活性，及与甜菜夜蛾核型多角体病毒毒力的相关性。应用昆虫免疫学、生理学、分子生物学等学科的研究方法，在筛选和克隆出抗核型多角体病毒感染的宿主围食膜功能基因以及酚氧化酶、细胞凋亡caspase基因、抗菌肽gloverin基因的基础上，重点研究取食不同寄主植物的感病和未感病甜菜夜蛾在上述功能基因表达量和围食膜结构特征等方面的差异，解析寄主植物对核型多角体病毒感染宿主甜菜夜蛾的影响及机理。预期研究结果不仅在理论上将有助于深入理解“植物-昆虫-病毒”的相互关系，且在害虫防治实践上为在不同作物上利用昆虫病毒防治甜菜夜蛾提供科学依据。

项目以黄豆、甘蓝和蕹菜共3种寄主植物、甜菜夜蛾和甜菜夜蛾核型多角体病毒（SeMNPV）为研究系统，克隆了宿主围食膜功能基因以及酚氧化酶、细胞凋亡caspase基因、抗菌肽gloverin基因，测试了取食不同植物的感病和未感病甜菜夜蛾在上述功能基因表达量和围食膜结构特征等方面的差异。研究结果表明：1）植物显著影响感病宿主的存活率和存活时间；取食黄豆的甜菜夜蛾对病毒最敏感（半致死剂量最低：110.5 OBs/虫），仅为取食蕹菜的0.09倍（半致死剂量为1222.4 OBs/虫）；研究发现植物叶片中总酚和过氧化物酶抑制了病毒对宿主的致病力，而过氧化氢酶、超氧化物歧化酶、几丁质酶能增强这种致病力；2）寄主植物不影响未感病幼虫的中肠组织，但幼虫感染病毒后，其中肠和围食膜（PM）受损程度因植物种类不同而存在差异；黄豆介导的感病幼虫中肠受损程度最大，甘蓝的次之、蕹菜的最小；电镜扫描发现，以黄豆、甘蓝和蕹菜为食源的感病幼虫，PM出现孔洞的时间点分别在感毒后第2、2、3 h，修复时间点分别在3、6、12 h；3）转录组测序表明，甜菜夜蛾感毒后有1785个unigene表达量发生变化；通过RNAi筛选两个重要的围食膜功能基因，并测定了这两个基因的表达。取食黄豆的幼虫肠黏蛋白SeIM基因的表达量显著高于取食甘蓝和蕹菜的，而取食甘蓝和蕹菜的幼虫的几丁质合成酶SeCS基因表达量显著高于取食黄豆的；4）取食蕹菜的感毒幼虫血淋巴中多巴脱羧酶、酚氧化酶和酪氨酸羟化酶的活性及基因表达量最高，取食甘蓝的次之，取食黄豆的最低；感毒24h后，取食蕹菜和甘蓝的幼虫抗菌肽gloverins基因表达量显著高于取食黄豆和人工饲料的，而取食蕹菜的幼虫gloverins蛋白含量始终高于取食黄豆和甘蓝的；5）感染病毒后的幼虫血细胞凋亡率迅速升高，且在不同食物处理间存在显著性差异，取食蕹菜和甘蓝的感毒幼虫细胞凋亡率显著高于取食黄豆的；取食3种植物的幼虫被感染病毒后第12-72h，促使细胞发生凋亡的甜菜夜蛾半胱天冬酶基因相对表达量显著上升，而细胞凋亡抑制基因相对表达量下降；取食蕹菜和甘蓝的幼虫，半胱天冬酶基因表达量显著高于取食黄豆的，取食黄豆的宿主凋亡抑制基因相对表达量高于取食蕹菜与甘蓝的。研究结果不仅从理论上解析了植物调控植食性昆虫与昆虫病毒互作的机理，且在实践上为更精准使用病毒杀虫剂防控不同作物上害虫提供了依据。