Figure 1.

Normal phloem transport (a) and disruption of transport during infection or defence (b). Green cells are mesophyll, teal cells are companion cells, purple cells are phloem cells and all gaps between cells are plasmodesmata, except for sieve plate pores between phloem cells. Numbered generalized processes are shown in the figure and described in the processes section for representative pathogens. The temporal order of infection and defence processes in the phloem remain unclear (see text for details).