The Study And Functional Analysis Of Viral DsRNA In Phomopsis Vexans

Phomopsis vexans is one of the most devastating diseases of eggplant, seriously affecting its yield and quality; Mycoviruses widely spread in the fungal kingdom and many decline virulence-associated viruses have been found in numerous fungi. There is great prospect for using mycoviruses to control fungal diseases. The discovery and characterization of more novel mycoviruses might supply more abundant viral material and use of decline virulence-associated virus controlling P. vexans is a new idea. In this study, mycovirues of the strain Pv-HN-1,which is separated from Hunan Province, and its interaction with the host were analyzed. The innovative results were shown below:1. This is the first report of viral dsRNA in P.vexans. The three dsRNAs, which extracted by the cellulose CF11 method, followed by treatment of enzyme digestion, showed by agarose gel electrophoresis, were named as dsRNA-L, dsRNA-M and dsRNA-S according to their molecular weights.2. The complete genome sequence of the dsRNA-M harbored in strain Pv-HN-1 were obtained using an M-SPAT method demonstrated that the genome of dsRNA-M, named as Phomopsis vexans RNA virus 1(PvRV1), is 5076nt, contains two non-overlapping reading frames (ORF1 and 2) and showed significant similarity to those of capsid protein (CP) and RNA-directed RNA polymerase (RdRp), respectively, of virus in the family Totiviridae. Phylogenetic analysis indicated that PvRV1 is closely related to the Ustilaginoidea virens RNA virus 3 (UvRV3) which is in U. virens. in the family Totiviridae. (The result has been published in Archives of Virology),In the subsequent elimination of experiment and its successive transfer culture,it founds that dsRNA-M and dsRNA-S may have some relevance or synergy because of they are always appear together. And dsRNA-L is a independent virus.(the most of sequence of dsRNA-L have been completed and it is identified as endornavirus).3. By protoplast regeneration assays for elimilation of virus, we got three strains, one includes no virus, one includes dsRNA-L only and one includes dsRNA-S and dsRNA-M, were named as Pv-HN-1 C-C, Pv-HN-1 C-L and Pv-HN-1 C-MS respectively. The comparison of colony growth rate revealed that Pv-HN-1 C-C grows fastest and Pv-HN-1C-MS grows faster than Pv-HN-1C-L. The difference between their virulence is that the pathogenicity of Pv-HN-1C-C enhanced significantly and the pathogenicity of Pv-HN-1C-L decreased significantly which were compared with Pv-HN-1.