Abstract: P0 of Potato leafroll virus is encoded by the open reading frame1（ORF1）. Here we show that P0 of Potato leafroll virus （PLRV）displays strong silencing suppressor activity in a transient expressin assay based upon its ability to inhibit PTGS of green flurescent protein（GFP）mRNA when expressed in agro-infitraten leaves of Nicotiana benthamiana containing a GFP transgene（16c）.We found PLRV-P0 gene sequence containing two duplicate WG motif by sequence analysising. The 87 and 140 Tryptophan（W）of Potato leafroll virus P0 gene were mutated by Alanine（A）（named P0WA）, the plant expression vector pCAMBIA1300-CE-P0, pCAMBIA1300-CE-P0WA was constructed. We found that there was green fluorescent under fluorescence microscopy after PLRV-P0 and AGO co-injection when expressed in agro-infiltraten leaves of Nicotiana benthamiana. However, there was not green fluorescent under fluorescence microscopy after PLRV-P0WA and AGO co-injection.We conclude that the PLRV-P0 interacted with AGO protein and repeated WG motif was the key amino acids.

Key words: Potato leafroll virus（PLRV）, P0 protein, Suppressin of RNA silencing, AGO protein Interaction