Figure 4.

A, Results of modifier experiments showing that alkalinization of the root tip causes disruption of the signaling pathway. ●, Control; ○, 100 μm benzoic acid; ▾, 1.25 μm bafilomycin A1; ▿, 0.3 μm bafilomycin A1. B, Results of modifier experiments showing that acidification of the root tip causes enhancement of the signaling pathway. ●, Control; ○, 50 μm procaine; ▾, 500 μm methylamine; ▿, 100 μm procaine. Diagrams of Arabidopsis seedlings demonstrating the direction of roots bending at various times during the experiment. Stimulus 2 was applied at time = 0. Experiments are averages of 20 separate roots; for clarity, ses are not shown, but are approximately ±2 degrees of curvature for each point.