Figure 3.

Determinants of time scales. To determine what factor governs the time scales of auxin accumulation in the controlled area (CA in the scope of this figure) under Effl↓ we followed the changes in the auxin concentration over time in five different reference segments, created by reducing the effective permeabilities with different factors for P_out,bg and all others (P_other = {P_out,low, P_out,high, P_in}). (A–C) Each graph shows simulations that share a common factor. If all five curves have a similar shape, this common factor is the most likely key determinant of the auxin accumulation time scales. (A–C) $\frac{\text{d}\left[\text{IAA}\right]}{\text{d}t}$ In the most central cell of the CA [indicated with “X” in (E)]. (A) Ten-fold (further) reduction of efflux inside the CA. Steady state profiles and overviews matching these curves in (D,F) respectively. (B) Similar steady state [IAA] in the CA: [IAA]_CA ≈ 2–6 C_v. (C) P_out,low = 0.05 μm s⁻¹ inside the CA. (D) Steady state [IAA] profile along the dotted line in (E) for all curves in (A). (F) Legend for all: P_out,bg/100, P_other/1 red pluses, P_out,bg/10, P_other/1 cyan crosses, P_out,bg/1, P_other/1 (original DZ segment) green asterisks, P_out,bg/100, P_other/10 blue open squares, P_out,bg/10, P_other/10 magenta filled squares, next to steady states for the curves in (A). Note that only in (C) all five curves show a similar shape. This implies that the value of P_out,low in the CA, which governs the distribution of auxin over the CA, is the key determinant of the time scales of local auxin accumulation under Effl↓.