Figure 2.

Outline of the experimental protocol designed to test the effects of various pH modifiers on the signaling pathway for root gravitropism. At T = −30 min, vertical roots were rotated through 135° (Stimulus 1). At T = −5 min, 0.1 μL of control or pH-modiying solutions was applied solely to the root cap. Roots were returned to vertical at T = 0 (Stimulus 2). Three possible resultant morphologies are shown: I, Disrupted signaling; II, normal signaling; and III, enhanced signaling.