小麦黄花叶病毒P3蛋白致病功能域的鉴定和分析

小麦黄花叶病毒(Wheat yellow mosaic virus,WYMV)隶属于马铃薯Y病毒科(Potyviridae)大麦黄花叶病毒属(Bymovirus),其基因组由两条正义单链RNA组成,共编码10个蛋白。先前的研究表明,马铃薯Y病毒组多种病毒编码的保守蛋白P3具有多种功能,在病毒复制、致病性、克服宿主抗性、细胞间移动等方面均具有重要作用,而P3在大麦黄花叶病毒属中是否有类似功能目前还未见报道。本研究利用烟草脆裂病毒(Tobacco rattle virus,TRV)介导的本氏烟基因沉默系统,明确了WYMV的P3碳端在本氏烟上具有致病功能域P3-C,但完整的P3则不具有致病能力。进一步移码突变研究表明,P3-C的致病性是由其编码的多肽引起的,而非病毒来源的小干扰RNA介导的宿主基因沉默。同时P3-C的两个跨膜结构域对致病性具有重要作用,单独表达任何一个跨膜结构域P3-C均不能在本氏烟上引起明显症状。

Identification and analysis on pathogenicity-related domain of P3 protein of wheat yellow mosaic virus

Wheat yellow mosaic virus (WYMV) belongs to the genus Bymovirus, family Potyviridae. Its genome consists of two sense single-stranded RNAs encoding a total of 10 proteins. Previous studies had shown that the conserved protein P3 encoded by potyviruses had multiple functions and played an important role in viral replication, pathogenicity, overcoming host resistance, and cell-to-cell movement. However, whether P3 had similar functions in bymovirus had never been reported yet. In this study, tobacco rattle virus(TRV)-mediated gene silencing system in Nicotiana benthamiana was used to study the function of WYMV P3. Our results indicated that C terminal of WYMV P3 (P3-C), but not the whole P3, had a pathogenic-related functional domain in N. benthamiana. Further frame shift mutation confirmed that, rather than the viral small interfering RNA-mediated host gene silencing, the pathogenicity was caused by the polypeptide of P3-C. In addition, the pathogenicity on N. benthamiana disappeared when any of the two predicted transmembrane domain in P3-C were mutated, indicating the important roles of the transmembrane domains in P3-C pathogenicity.