The Flux-Based PIN Allocation Mechanism Can Generate Either Canalyzed or Diffuse Distribution Patterns Depending on Geometry and Boundary Conditions
Figure 3
Demonstration of competition for flux between neighbouring cells.
In both simulations the bottom left-hand cell is a perfect sink while all other cells generate auxin at a rate of 0∶4 µmolhr−1. (A) Neighbours of the sink share the auxin effluxing from their mutual neighour in the top right-hand corner, so they each receive enough to generate a small concentration of PIN. They also receive identical PIN-mediated flux, even if the top left cell enjoys an initial advantage of 10−10µmol µm−2; indicating that identical PIN concentrations constitute the stable configuration. (B) Auxin transport between the top two cells is blocked, as indicated by the black zigzag. The top right-hand cell now fluxes auxin exclusively to its lower neighbour. This raises its total auxin efflux enough to express PIN strongly towards the sink, while the sink’s other neighbour has weaker PIN expression than its couterpart in (A). The feedback exponent is given by . (C) This colour bar indicates the auxin concentration in µmol µm−3 in this figure and the next one.