How do viruses traffic on the 'vascular highway'? [Erratum: Oct 1996, v. 1 (10), p. 360.]

Considerable progress has been made in understanding how plant viruses move from cell to cell in infected plants. Far less is known of the mechanisms by which viruses move long distances in the direction of photoassimilate flow in the vascular system, and this represents an important frontier in plant virology. Recent evidence has suggested that the mechanism(s) by which viruses enter and exit the vasculature may be quite different from those involved in cell-to-cell movement, and the challenge is to determine precisely how, where and when this occurs. Our attention has focussed on the companion cell-sieve element boundary, and on the need to identify viral and host factors involved in these processes. Central to these studies will be the identification of the viral form(s) that are involved in long-distance movement. The use of new technologies may provide insight into these questions, and the foundation for a thorough understanding of viral movement and macromolecular trafficking within the phloem.