柑橘衰退病毒(CTV)引起的柑橘衰退病对世界柑橘产业危害严重，主要由褐色橘蚜传播。寄主-病毒-媒介昆虫三者互作的分子机制是研发新型虫传病毒病防控措施的基础，然而国内外在这一领域的研究亟需加强，尤其CTV沉默抑制子p20与转录因子AP2/ERF1a互作如何调控植物激素尚是一片空白。前期研究发现CTV影响寄主水杨酸(SA)含量和相关基因表达，抑制褐色橘蚜种群增长，并以p20为诱饵蛋白筛选出一个与植物病毒蛋白互作的新转录因子AP2/ERF1a。在此良好基础上，本项目拟用Pull-down、BiFC、CRISPR/Cas9、LC-MS、RT-qPCR、ChIP和转基因等技术，从蛋白质互作和转录因子靶基因等角度，明确p20和AP2/ERF1a在CTV调控SA介导的甜橙对褐色橘蚜抗性中的功能，解析p20调控SA信号途径抑制褐色橘蚜种群增长的分子机制，预期结果有望为蚜传病毒病的绿色防控提供新思路。

Citrus tristeza virus (CTV) which causes citrus tristeza disease is distributed worldwide. Along with the development of some susceptible cultivars within the latest 20 years, stem-pitting tristeza has become a threat to citrus industry. CTV is mainly transmitted by Toxoptera citricidaas in a semi-persistent way. Understanding the relationship of the host-virus-insect triangle and their interaction molecular mechanisms is the basis of control measures for disease spreading by insects. Therefore, it is of significant importance to know these molecular mechanisms well and comprehensively. However, so far, the knowledge about these molecular mechanisms is still limited, in particular for the information about how CTV p20 and AP2/ERF 1a regulate phytohormone in citrus trees. In our previous study, CTV was found to be able to decrease the population growth of T.citricida by affecting salicylic acid (SA) accumulation and significantly changing the expression pattern of certain genes in SA defence pathway in infected plants. Interestingly, AP2/ERF 1a, a novel protein binding with plant viruses, which encodes a AP2/ERF family transcription factor, was obtained using a sweet orange cDNA library of yeast two hybrid system screening by CTV p20 as bait protein. Based on our previous good research data, the advanced techniques, such as Pull-down, BiFC, CRISPR/Cas9, LC-MS, RT-qPCR, ChIP, and transgenic technology, etc., will be used to clarify the function of CTV p20 and AP2/ERF 1a in CTV regulating SA-mediated resistance for T. citricida, and to reveal the molecular mechanism of disruption of SA -mediated plant defence to T. citricida by a Citrus tristeza virus p20 silencing suppressor The predicted results could provide novel idea and method for preventing and controlling epidemic viruses such as Citrus tristeza transmitted by T. citricida.