MOVEMENT OF VIRUS AND PHOTOASSIMILATE IN THE PHLOEM - A COMPARATIVE-ANALYSIS

Recent progress in the study of short-distance (cell-to-cell) movement of plant virus, facilitated by 'movement proteins', has led to a resu rgence of interest in long-distance virus transport in the phloem. Rel atively little is known about phloem-specific barriers to virus moveme nt or about the form in which virus enters, travels within and exits t his tissue. Progress in understanding virus and photoassimilate transp ort is limited by a paucity of information on the substructure and pro perties of plasmodesmata at specific interfaces. The direction of viru s movement, once it has entered the phloem, can be understood by follo wing photoassimilate translocation, a complex and dynamic process infl uenced by plant growth, development and vascular topology.