Fig. 5.

Arabidopsis max4 and tir3 mutants and their interactions. (A) Aerial phenotype of 6-week-old Columbia WT, max4–1, tir3–101, and max4–1,tir3–101 plants. (B) Mean auxin mass (pg) exported from 2 cm stem segments excised from the apical, medial, and basal region of the bolting stems of WT (Col) and max4–1 mutant (max4) plants. For the “Col no apices” samples, all visible shoot apices above the point of stem excision were removed 24 h before the stem segments were excised. The auxin was collected from the basal end of the segments, except in the “inverted” segment samples, where it was collected from the apical end. Error bars: SEM, n ≥ 4. (C) Mean radiolabelled auxin (cpm) transported along excised stem segments of the genotypes shown in (A). Error bars: SEM, n = 10. (D) Simulation of max mutant. PIN concentrations, auxin fluxes and auxin concentrations are increased with respect to the WT (Fig. 3E). (E) Simulation of tir3 mutant. PIN concentrations, auxin fluxes, and auxin concentrations are decreased with respect to the WT (Fig. 3E). (F) Simulation of max, tir3 double mutant. PIN concentrations, auxin fluxes, and auxin concentrations are increased with respect to the WT (Fig. 3E), but decreased compared to max (D).