The tobacco mosaic virus 30K movement protein in transgenic tobacco plants is localized to plasmodesmata

Transgenic tobacco plants expressing a gene encoding the tobacco mosaic virus (TMV) movement protein (30K) were studied using immunocytochemical techni-ques. The movement protein was shown to be localized within or on most of the plasmodesmata observed in the transformed plant. These results are consistent with the idea that the movement protein interacts with the plasmodesmata to facilitate the cell-to-cell spread of TMV. The passage of a plant virus from cell to cell is assumed to be via the intercellular connections known as plasmodes-mata. The structure of these junctions (for review see Robards & Lucas, 1990) in the 'normal state ' provides a barrier to the intercellular passage of the virus owing to the size limitations of the channel neck constrictio