Cell-to-Cell but Not Long-Distance Spread of RNA Silencing That Is Induced in Individual Epidermal Cells

摘要

A Turnip crinkle virus (TCV)-based system was devised to discriminate cell-to-cell and systemic long-distance spread of RNA silencing in plants. Modified TCV-GFPΔCP, constructed by replacing the coat protein (CP) gene with the green fluorescent protein (GFP) gene, replicated in single epidermal cells but failed to move from cell to cell in Nicotiana benthamiana. Mechanical inoculation of TCV-GFPΔCP induced effective RNA silencing in single epidermal cells which spread from cell to cell to form silenced foci on inoculated leaves, but no long-distance systemic spread of RNA silencing occurred. Agroinfiltration of TCV-GFPΔCP was, however, able to induce both local and systemic RNA silencing. TCV coinfection arrested TCV-GFPΔCP-mediated local induction of RNA silencing. Possible mechanisms involved in cell-to-cell and long-distance spread of RNA silencing are discussed.