一种棉花多酚氧化酶基因对昆虫取食应答存在差异的原因解析

This study is base on the found that a new cotton polyphenol oxidase( PPO) gene have special response to the damages of Helicoverpa armigera, Spodoptera litura,Spodoptera exigua. By construct the model of PPO reponse to the damages of those three insects, to understand the relationship of damage and PPO expression quantity. Stimulate the cotton use stimulating factor compounding of those three insects, to find the reasons of special response, and the function of insect salivary components in this response. To make sure the fuction of PPO in cotton defenses, bioassay was carry out use artificial diet. To study the feeding antagonism in those three insects, learn the purport of PPO response to insect damage, we use one insect species damaged cotton feeding another two insects. This study is signality to learn the mechanism of induce defense of cotton, the interaction between herbivore insects and cotton, herbivore insects themselves. Also can use for reference of transgenic technolgy, lay a foundation for deeply research the interaction between herbivore insects and cotton, herbivore insects themselves, open up the pest management methods.

多酚氧化酶基因在调控植物诱导防御害虫系统具有重要功能。申请者在先期研究中鉴定获得一种新的棉花多酚氧化酶基因，该基因对棉铃虫、斜纹夜蛾、甜菜夜蛾取食诱导具有特异应答反应。以此为基础，本研究拟采取分子生物学及信息学技术构建该基因对三种昆虫取食应答反应模型，了解在昆虫不同取食刺激条件下，该多酚氧化酶基因的表达量变化特征。使用三种昆虫组合刺激因子刺激棉花，探究差异应答的原因及昆虫反吐液在特异应答中的作用，并鉴定诱导因子的类型。结合人工饲料进行生物测定，明确这种多酚氧化酶在棉花防御昆虫取食中的作用，同时使用某一昆虫诱导后棉花植株饲喂另两种昆虫，了解三种昆虫间取食拮抗作用，解析该基因应答昆虫取食的意义。本项目对了解棉花的诱导防御机制，探讨棉花与植食性昆虫、植食性昆虫之间相互关系意义重大，对于基因调控转基因具有借鉴意义，同时为深入揭示植物与植食性昆虫、植食性昆虫之间相互作用，开辟害虫治理方法打下基础。

为了明确棉花Ghppo1基因在棉花防御害虫取食的作用以及基于Ghppo1基因的棉铃虫和甜菜夜蛾互作，开展本研究。研究结果表明，转Ghppo1基因拟南芥对棉铃虫的生长发育存在不利的影响。荧光定量PCR结果表明棉花中Ghppo1基因的表达受1龄棉铃虫取食和喷洒茉莉酸甲酯的正调控，而3龄棉铃虫取食和喷洒水杨酸甲酯对棉花中Ghppo1基因的表达量无影响，棉花中的PPO酶活性表现出和Ghppo1基因的表达量相同的变化趋势。5龄末期至6龄初期棉铃虫口腔分泌物能够压制机械处理后棉花中的Ghppo1基因表达量和PPO酶活性。棉花中JA途径关键基因的表达量受1龄棉铃虫取食正向诱导，而对3龄棉铃虫的取食没有明显的应答。1龄棉铃虫取食诱导后的棉花植株对3龄棉铃虫和甜菜夜蛾幼虫的防御能力增加。以上研究结果证明，棉花中可能存在基于Ghppo1基因调控的昆虫间取食互作现象。