Figure 1.

Short- and long-term changes in InsP₃ precede gravitropic bending in oat pulvini and not in internodal tissue. InsP₃ levels were measured in upper (dashed lines) and lower (solid lines) halves of gravistimulated oat pulvini (A and B) or internodal tissue (C and D) at the indicated times after gravistimulation. The data points represent the percentage change in InsP₃ over the vertical control (set at 100%) and are the average of three independent experiments assayed in duplicate. The vertical bars indicate the range. No significant change in InsP₃ levels could be detected between halves from vertical control plants (data not shown). Changes in InsP₃ over the first 3 min of gravistimulation in upper and lower halves of pulvinus (A) and internodal tissue (C). Changes in InsP₃ over the first 60 min of gravistimulation in upper and lower halves of pulvinus (B) and internodal tissue (D). InsP₃ levels in vertical controls were in the range of 200 to 300 pmol g⁻¹ fresh weight for both pulvinus and internode.