草莓镶脉病毒（SVBV）是一种严重危害草莓的双链DNA病毒。目前，SVBV功能基因研究在国内外尚未见报道，特别是SVBV自身编码的P6蛋白可能是一个重要的致病因子，明确P6蛋白的功能有助于深入了解SVBV甚至双链DNA病毒的致病机制。本项目首先通过瞬时浸润和转基因稳定表达技术，明确P6蛋白在病毒侵染和症状形成中的作用。再鉴定P6蛋白对16c本氏烟系统沉默的抑制以及对已建立系统沉默的16c本氏烟的影响，探讨P6蛋白能否延迟系统沉默和阻止沉默信号的传导，从而明晰P6蛋白在RNA沉默过程中的作用阶段。最后深入探讨P6蛋白在RNA沉默过程中能否与寄主植物的RNA沉默调控因子RDR或DCL相互作用，以及能否与dsRNA结合来干扰siRNA的产生，从而进一步明确P6蛋白在RNA沉默过程中的作用位点。本研究的开展对揭示寄主植物和双链DNA病毒之间防御和反防御的分子机制以及控制病毒病危害均具有重大意义。

Strawberry vein banding virus (SVBV) is a circular double-strand DNA viruses which can seriously damage strawberry. At present, the research of gene function of SVBV has not been reported at home and broad. Especially, protein P6 encoded by SVBV itself probably is a great important pathogenic factor. To ascertain function of protein P6 of SVBV will contribute to deeply understand pathogenic mechanism of SVBV and even double-strand DNA viruses. Firstly, our program will clarify the function of protein P6 during virus infection and symptom formation by transient expression and stable transgene expression method. Secondly, effect stage of protein P6 during RNA silencing process was clarified through identifing that suppression of protein P6 to systemic silencing of transgenic Nicotiana benthamiana line 16c and influence of protein P6 to systemic silencing been constructed and exploring that whether protein P6 can delay systemic silencing and block silencing signal transduction. Finally, effect site of protein P6 during RNA silencing process was further clarified through deeply exploring that whether protein P6 can interact with regulating factor RDR and DCL during RNA silencing process and whether protein P6 can combine with dsRNA to interfer production of siRNA. This reseach work has great significance for revealing molecular mechanisms of defense and anti-defense between host plant and double-strand DNA virus and controlling virus diseases.