唾液功能因子BtLAC1增强烟粉虱寄主适应性的生理与分子机制

Saliva plays an important role in the interaction between pest and host plant. The study of salivary functional factors is one of the research hotspots of insect-plant interaction in recent years. Our previous studies showed that Bemisia tabaci saliva composed of protein laccase 1 (BtLAC1), who promotes the adaptability of B.tabaci to host plants. This study will lay a foundation for revealing the response mechanism of plant defense regulated by pests. In this proposed project, using techniques and methods combined with insect behavior, physiology and molecular biology, we will research BtLAC1 of B. tabaci in the following aspects: (1) The function of BtLAC1 in whitefly was analyzed by researching the changes of feeding behavior of whitefly after silencing BtLAC1 and the fitness of whitefly feeding on tobacoo which BtLAC1 overexpressed. (2) The effect of BtLAC1 on plant defense related substances such as JA, SA and polyphenols, and further screening and functional analysis of BtLAC1 interaction proteins in tobacco. To analyze the physiological, biochemical and molecular mechanisms of BtLAC1 enhancing host adaptability of B.tabaci, both insects and plants will be studied. This study will help us to clarify the mechanism of BtLAC1 improving host adaptability and invasion mechanism of B.tabaci, and provide the basis for the development of new strategies for insect-resistant plants and the control of whiteflies.

唾液在害虫与寄主植物互作中发挥重要作用，唾液功能因子研究是近年来昆虫-植物互作领域研究热点之一。前期研究发现唾液功能因子漆酶1(BtLAC1)促进了烟粉虱对寄主植物的适应性，其作用机制的研究将为揭示害虫调控植物防御反应的机制奠定基础。本项目以烟粉虱为研究对象，通过行为学、生理学和分子生物学等技术，拟开展以下工作：(1)通过研究沉默BtLAC1后烟粉虱取食行为变化，以及取食BtLAC1过表达烟草对烟粉虱适合度的影响，解析BtLAC1在虫体中的功能；(2)通过研究BtLAC1蛋白对植物防御物质JA、SA和多酚的影响，并进一步对植物中BtLAC1互作蛋白进行筛选和功能分析，明确BtLAC1对植物的作用。通过从昆虫与植物两方面功能研究，解析BtLAC1增强烟粉虱寄主适应性的生理生化和分子机制。成果有助于揭示烟粉虱寄主适应性和入侵机制，为发展转基因抗虫植物和烟粉虱防治新策略提供依据。

唾液功能因子能激发或者抑制植物的防御反应，在植食性昆虫与寄主植物互作中发挥重要作用。前期研究发现一种烟粉虱唾液分泌蛋白漆酶1 (BtLAC1)，在烟粉虱唾液腺和中肠中高表达，可能是唾液功能因子，本项目对BtLAC1在烟粉虱中的功能和作用机制进行了进一步的研究，主要结果为：（1）通过超高效液相色谱质谱测定了BtLAC1基因沉默的烟粉虱取食的番茄叶片中次生代谢产物的变化，发现与对照相比，与防御相关的次生代谢物的数量上调的减少、下调的增多。（2）在烟草叶片中过表达BtLAC1会引起其茉莉酸途径相关基因表达量上调，而被BtLAC1基因沉默的烟粉虱取食的烟草，水杨酸途径上相关基因表达量上调。进一步研究发现BtLAC1可与烟草中的COP9互作，激活茉莉酸途径，引发植物防御反应。（3）烟粉虱取食过表达BtLAC1的烟草后产卵量显著降低，BtLAC1 RNAi的烟粉虱取食正常烟草后产卵量显著增高，说明BtLAC1与烟粉虱的产卵量呈现负相关性，推测是由于BtLAC1激活了烟草茉莉酸防御反应从而对烟粉虱产生了不利影响。综上所述推测BtLAC1是一种激发子能激发植物的防御反应。本研究揭示了烟粉虱唾液激发子激活植物防御的机制，为研究烟粉虱绿色新型防控技术提供理论依据。