绿盲蝽唾液腺候选效应子Al106调控植物免疫反应的分子机制解析

绿盲蝽是危害我国棉花、果树、蔬菜和其他农作物的杂食性刺吸式害虫，危害严重。昆虫取食时分泌效应子到植物体内调控寄主抗虫免疫反应来促进营养的吸收，我国科学家在昆虫效应子调控寄主免疫机制方面已经取得了多项重要进展，但对绿盲蝽效应子的研究目前尚不多见。本项目前期从绿盲蝽中筛选到一个候选效应子Al106，它是一个带有信号肽且具有肽脯氨酰顺反异构酶结构域的亲环蛋白，编码基因在成若虫取食期以及唾液腺中高表达，在烟草过表达后能抑制植物病原菌激发子INF1引起的细胞死亡和PAMP诱导的活性氧爆发，说明它是一个潜在的效应子。因此，本项目拟以Al106候选效应子为切入点，开展效应子的分泌、酶活及其与干扰植物抗虫免疫反应的关系、靶标鉴定与功能分析等研究，深入揭示昆虫唾液腺亲环蛋白作为效应子操控植物免疫防御反应的分子机制，为昆虫与植物之间的“防御-反防御”的认识奠定理论基础，为绿盲蝽的防治提供新的研究思路和方法。

The mired bug Apolygus lucorum is an omnivorous piercing-sucking insect that endangers cotton, fruit trees, vegetables and other agricultural crops in China, causing massive economic losses. During herbivorous insect feeding, the effectors secreted from salivary glands are injected into plants to interfere with host immune responses for facilitating nutrient ingestion. Available literature on insect effectors has revealed exciting insight into the molecular mechanisms of plant–insect interactions. However, the studies of salivary gland effector in A. lucorum are limited. Prior to this research proposal, we have characterized one candidate salivary gland effector named Al106 from A. lucorum, which encodes a cyclophilin protein with a signal peptide, and contains a peptidyl-prolyl cis–trans isomerases (PPIase) domain. This gene was highly expressed at the feeding stages of nymph and adult, and its mRNAs were especially highly enriched in the salivary glands. Transient in planta overexpression of Al106 in Nicotiana benthamiana inhibited the cell death and reactive oxygen burst (ROS) induced by the plant pathogen Phytophthora infestans PAMP, INF1, therefore, all the evidence indicated that Al106 is a potential A. lucorum effector. This project intends to further explore the roles of Al106 in phloem sap ingestion and modulating plant immunity, to illustrate the relationship between PPIase enzyme activity and molecular functions of Al106, and to identify the target proteins of Al106 using protein-protein interaction assays. Eventually, this project will uncover the molecular mechanisms of an insect cyclophilin secreted into host plant cells as effectors to manipulate plant immune defense responses. Our results will offer new insight into the multiple–layered mechanisms of “defense and counter-defense” during insect-plant interactions, and this research will also provide novel ideas and methods for the control of A. lucorum.