Figure 3.

Chemical and immunological inhibition of apyrase activity induces stomatal closure. A, Application of anti-apyrase immune sera induced stomatal closure in whole leaves, but application of control preimmune sera had no effect on the aperture (5.2 μm average width for control). B, Application of apyrase inhibitor NGXT 191 induced stomatal closure in epidermal peels, and 100 μm PPADS blocked this closure, but 100 μm PPADS had no effect alone (5.3 μm average width for control). Apertures were measured as width/length after 1 h of treatment for peels and after 2 h of treatment for leaves. Error bars represent se. Different letters above the bars indicate mean values that are significantly different from one another as determined by Student’s t test (P < 0.05; n ≥ 50). These data are representative of three or more biological repeats.