Figure 1
Diagram of the experimental protocol. A (a) Schematic diagrams of gravistimulation and detection of aequorin luminescence. A plate of Arabidopsis seedlings was mounted under a photomultiplier tube (PMT) in a light-tight dark box which was rotated by a stepping motor, enabling gravistimulation while monitoring the intensity of the aequorin luminescence. Changes in the direction of the Arabidopsis seedlings in the experimental protocol are illustrated. The arrow F shows the direction of forward rotation and B shows that of backward rotation. (b) Time course of the magnitude of gravitational acceleration applied to Arabidopsis seedlings. Seedlings were rotated + 180o (forward rotation) at 0 s and − 180° (backward rotation) at 400 s. (B) Schematic illustration of a typical time course of changes in the luminescence ratio induced by gravistimulation. The peak of the transient [Ca2+]c-increase (light shading) is shown with a white arrowhead, the peak of the slow [Ca2+]c-increase (intermediate shading) with a black single arrowhead, and the peak of the very slow [Ca2+]c-increase (dark shading) with a black double arrowhead. The transient [Ca2+]c-increase (light shading) and the slow [Ca2+]c-increase (intermediate shading) are called biphasic [Ca2+]c-increases overall. Parameters (T1, T2, τ1, τ2, A0, A0′, A1, A1′, A2, and D) are shown and listed in Supplementary Table S1.
