Figure 1.

Effect of spermidine on stomatal movements. Epidermal peels were obtained from 4-week-old V. faba leaves. Stomatal pore size was measured after 2-h incubation in peel solution containing 0, 0.1, 0.5, 1.0, 3.0, and 6.0 mm spermidine. For stomatal opening assay (A), peels were collected from the plants before light cycle, and the initial stomatal pore size was typically in the range of 3.7 ± 0.6 μm. After 2-h illumination, the pore size reached 14.0 ± 2.7 μm in the control solution without spermidine. For stomatal closure assay (B), peels were collected from the plants 4 h after light cycle, and the initial pore size was 12.4 ± 0.6 μm. The data in both A and B are presented as mean ± se from seven individual experiments.