Fig 5. Steady state equilibrium in a simulation on a regular grid of cells with heterogeneous auxin production rates.

(a) Initial conditions using a grid of 88 cells where most cells have an auxin production rate ${\alpha }_a^i=0.1$ except the two groups of 3 cells shown in darker green, where ${\alpha }_a^i=2.1$. (b) Using the production rates from (a) and parameters $({\beta }_a^i,\lambda ,\mu )=(5,5,0.1)$ in every cell, one of the possible steady state solutions. Each cell is colored in green according to the auxin concentration a _i (pale for the minimal concentration, dark green for the maximal). Cell membranes are colored according to the corresponding PIN concentration (with a red colormap). The flux J _{i → j} is represented by a blue arrow of width proportional to ∣J _{i → j}∣. (c) With parameters and initial conditions identical to those in (b) but with a diffusion coefficient D = 0.001 and a grid of non-regular cells.