Figure 1.

Within 10 s of gravistimulation, IP₃ levels increased 5-fold in the lower half of the pulvinus. IP₃ levels were measured in upper (dashed lines) and lower halves (solid lines) of gravistimulated maize pulvini at the times indicated. No significant difference in IP₃ levels could be detected between pulvinus halves from vertical control plants, as indicated in Table 1. The points represent the average of values from three experiments, assayed in duplicate. Vertical bars indicate the range. Basal IP₃ values were between 250 and 300 pmol/g (fresh weight).