RNA as a long-distance information macromolecule in plants.

A role for RNA as a non-cell-autonomous information macromolecule is emerging as a new model in biology. Studies on higher plants have shown the operation of cell-to-cell and long-distance communication networks that mediate the selective transport of RNA. The evolution and function of these systems are discussed in terms of an RNA-based signalling network that potentiates control over gene expression at the whole-plant level.