Figure 3.

Biphasic [Ca²⁺]_c transient induced by gravistimulation in Arabidopsis seedlings. A, Typical time course of changes in luminescence ratio induced by gravistimulation (±180° rotation). Approximately 40 Arabidopsis seedlings grown in a plate were turned 180° at the speed of 6 rpm at 0 s on the abscissa and retained at 180° for 800 s, which induced a biphasic [Ca²⁺]_c transient with an initial peak and a second one (white and black arrowheads, respectively). Subsequently, seedlings were turned back −180° at the same speed, which also induced the biphasic [Ca²⁺]_c transient with a small second peak (asterisk). The shaded and black bars above the data represent the rotational angles (0° and 180°, respectively). B and C, The effect of rotational angles on the initial and second [Ca²⁺]_c peaks. Plates of seedlings were turned through different angles at the speed of 6 rpm. The peak amplitudes of the initial (B) and second [Ca²⁺]_c transients (C) in response to 45°, 90°, 135°, and 180° gravistimulation are presented as hatched (n = 18), shaded (n = 22), black (n = 16), and white bars (n = 32), respectively. Data represent means ± ses. **, P < 0.05, the two-tailed Student's t test.