Rice ragged stunt virus segment S6-encoded nonstructural protein Pns6 complements cell-to-cell movement of Tobacco mosaic virus-based chimeric virus

The protein(s) that support intercellular movement of Rice ragged stunt virus (RRSV) have not yet been identified. In this study, the role of three nonstructural proteins Pns6, Pns7 and Pns10 in cell-to-cell movement were determined with a movement-deficient Tobacco mosaic virus (TMV) vector. The results showed that only the Pns6 could complement the cell-to-cell movement of the movement-deficient TMV in Nicotiana tabacum Xanthi nc and N. benthamiana plants, and both N- and C-terminal 50 amino acids of Pns6 were essential for the cell-to-cell movement. Transient expression in epidermal cells from N. benthamiana showed that the Pns6–eGFP fusion protein was present predominantly along the cell wall as well as a few punctate sites perhaps indicating plasmodesmata. Taken together with previous finding that the Pns6 has nucleic acid-binding activity ( Shao et al., 2004), the possible role of Pns6 in cell-to-cell movement of RRSV were discussed.