Rice Dwarf Virus-encoded Gene Silencing Suppressor Factor Screening And Verification

The first suppressor of gene silencing was discovered in 1998. Since then, increasing number of such proteins have been identified and their roles in interfering with gene silencing have been characterized, which extended our insight into the mechanisms of gene silencing in eukaryotes, pathogen-resistance, co-evolution between plants and viruses, analysis and application of functional genomics etc. RDV P10 is a RNA silencing suppressor in the RDV genome, that was found in 2005.We wanted to know that whether there are another suppressor in RDV genome. Seedlings of transgenic Nicotiana. benthamiana line 16c carrying the GFP gene were infiltrated with Agrobacterium tumefaciens harboring a functional 35S-GFP expression cassette alone, or together with each segment (S2, S6, S7, S8, S9, S11,S12) in RDV genome respectively. The GFP expression was not visible, i.e.GFP gene silencing ,starting from 7 days post-infiltration(dpi) on the leaves infiltrated with 35S-GFP alone or co-infiltrated with each segment except for S11, nevertheless the green fluorescence in the co-infiltrated patches of GFP+S11 was still strong visualized under UV light at the same time. Consistent with above fluorescent observations, Northern blotting analysis using probe specific for GFP showed GFP mRNA was abundant in the tissues coinfiltrated with S11+GFP, S10+GFP or Tav2b+GFP, whereas the level of GFP mRNA in the control (WT, GFP,) was not detectable .These results indicate that RDV Pns11 is another suppressor of gene silencing.