Figure 4.

Levels of IP₃ gradually increased in the lower half of the maize pulvinus between 3 and 7 h of gravistimulation. IP₃ levels were determined in upper and lower halves of pulvini from plants gravistimulated for 1 h (squares), 4.5 h (triangles), or permanently (circles). Only plants gravistimulated for longer than 4 h showed a bending response after 48 h. IP₃ levels in vertical control plants were 1,200 ± 150 pmol/g (fresh weight), and there were no significant differences between randomly cut pulvinus halves. The values plotted are the average of two experiments assayed in duplicate. Vertical bars indicate the range.