灰飞虱E3泛素连接酶在水稻条纹病毒调控介体寄主定向行为中的功能研究

The plant diseases caused by plant viruses are the “cancers” of the plant, and so far there is still no effective strategy to control them. According to previous report, the plant viruses can induce changes in vector behavior that enhance their transmission. We found that the small brown planthopper (SBPH) Laodelphax striatellus, after acquiring Rice stripe virus (RSV), prefers noinfected rice plants, and vice versa. However, the mechanism is unclear. Our study showed that the absence of the ubiquitin fusion protein or E3 ubiquitin ligase (E3) of SBPH could block RSV infecting antennae. To explore the function of the E3 on the host- orientation behavior of RSV-infected SBPH, this project focuses on the following studies: (1) Screening of RSV proteins interacting with E3; (2) Analyzing the mechanism of RSV invasion regulated by E3 and RSV interacting proteins in antennae; (3) The effect of E3 and RSV interacting protein on the host-directed behavior of RSV-infected SBPH. The expected results of this project can reveal the mechanism of the SBPH E3 regulating the spread of RSV in antennae, and the effect of SBPH E3 and RSV interacting proteins on insect behavior and physiology. This project not only enriches the theory of virus mediating insect behavior in plant-virus-insect tritrophic-system, but also provides new ideas for the prevention and control of insect-borne plant viral diseases.

植物病毒引起的病害被称为“植物癌症”，至今缺少有效的防治策略。研究表明植物病毒可通过改变介体昆虫行为利于其自身的传播和流行。水稻条纹病毒（RSV）侵染的介体昆虫灰飞虱同样被发现偏好选择无毒水稻植株，然而其深层机制尚不清楚。前期研究表明灰飞虱泛素融合蛋白或E3泛素连接酶（E3）的缺失会阻碍RSV对触角的侵染。为探索灰飞虱E3泛素连接酶在病毒调控介体寄主定向行为中的功能，本项目着重开展以下研究：（1）筛选与E3互作的RSV蛋白；（2）解析E3和RSV互作蛋白调控RSV侵染触角的机制；（3）挖掘E3和RSV互作蛋白对病毒调控灰飞虱寄主定向行为的影响。本项目预期结果能揭示灰飞虱E3调控RSV在触角中传播的机制，阐明了灰飞虱E3与RSV互作蛋白互作对灰飞虱行为学的影响。本项目既从病毒调控昆虫趋向行为角度丰富了植物-病毒-昆虫三级关系的理论体系，亦为介体昆虫传播植物病毒病的防治提供新思路。

植物病毒的存活和流行主要依赖载体的有效传播。70%以上的已知植物病毒由特异性介体昆虫传播，包括叶蝉、稻飞虱、蚜虫和粉虱等。大量研究表明植物病毒可操控介体昆虫行为利于自身传播。本项目团队前期研究同样发现水稻条纹病毒（RSV）侵染的介体昆虫灰飞虱偏好选择健康水稻植株。为探索其深层机制，本项目开展以下研究，并取得相应成果：（1）克隆获得灰飞虱泛素连接酶E3的两个亚型LsE3 ring和LsE3 Hect short序列全长。筛选与E3两个亚型互作的RSV蛋白，仅LsE3 ring与RSV非结构蛋白NS3的互作，并且确定互作位点。（2）解析E3和RSV互作蛋白调控RSV侵染触角的机制；抑制LsE3 ring表达阻遏其与RSV NS3在触角中的互作，减少了触角中RSV积累。（3）抑制LsE3 ring改变RSV侵染的灰飞虱对健康水稻苗行为偏好。（4）并拓展研究RSV侵染改变灰飞虱触角后寄主定向行为的化学感受机制，发现带毒灰飞虱触角差异表达的LsOBP4/7可能结合水稻挥发物β-紫罗兰酮、R(+)柠檬烯、1-辛烯-3醇和香茅醇影响带毒灰飞虱行为。本研究成果揭示灰飞虱的泛素连接酶LsE3 ring亚型能与水稻条纹病毒NS3蛋白互作，减少病毒在触角中的积累，从而转变飞虱获毒后趋向健康水稻的行为。进而发现RSV侵染触角中LsOBP4/7的高表达影响灰飞虱感受水稻化合物，因此产生偏好健康水稻的行为。本项目从全新的角度解析了病毒操控介体昆虫行为利于自身传播的深层机制，为植物病毒大规模传播提供了理论依据，亦为针对介体昆虫蛋白为靶标研发防治植物病毒病的药物提供了新策略。