Figure 6
A model for the reduction of viral population size as the infection moves from an IL to an SL.
(A) Infection foci formed by different viral variants are represented by colored dots on IL. The variant represented by the red dot expands right into a leaf vein and is expected to release a large amount of progenies for systemic movement (depicted by a thick solid red line extending to the SL) at the earliest time point. On the other hand, the blue variant is located slightly off a leaf vein and thus is expected to enter systemic movement phase in a smaller amount initially (depicted as a thin solid blue line). Other variants are expected to transit to the systemic movement phase at later time points (depicted as dashed lines). Note here that the use of major veins is purely for illustration purpose and does not imply that the entry of viruses into vascular bundles is exclusively through these veins. (B) In the SL, the larger amount of progenies of the red variant initiated more infection niches than the blue variant as they exit vascular bundles through the junctions of tertiary vein network (type III veins). Other variants, represented by dashed lines blocked at the sites of red and blue variants, are expected to be excluded from the niches already occupied by the early arrivers via as-yet-unknown mechanisms.
