Figure 2.

Melatonin, 5-methoxytryptamin, and 5-methoxyindole induce stomatal closure in N. benthamiana leaves. Measurements of stomatal apertures in N. benthamiana leaves 3 h after plants were treated with a 50 μM solution of MT, MT-homologs, and chitosan. Buffer-treated plants served as a control. 5-methoxytryptamin, 5-methoxyindole, and chitosan induced stomatal closure in N. benthamiana leaves, while the other test compounds and the buffer had no effect. (A) Representative micrographs of stomata in epidermal peels of treated plants 3 h after treatment with the test compounds. Lower panel of micrographs represents a higher magnification of individual stomata. (B) Stomatal data are the mean ± standard deviations (SDs; n = 150) of three independent experiments. Columns with different letters indicate significant differences in the aperture size of stomata of plants treated with the different test compounds as determined by a Duncan’s multiple range test.