Figure 6.

Sulfate-induced stomatal closure requires sulfate import into chloroplast mediated by SULTR3. A, Stomatal images for each treatment. Impact of sulfate (white, 15 mM MgSO₄), Cys (yellow, 500 µM), Gly (green, 500 µM), and ABA (gray, 50 µM) on stomatal aperture of the wild type and the SULTR3 quintuple mutant suffering from decreased sulfate uptake into chloroplasts. Control refers to water adjusted to pH 5.5 (black). Epidermal peels were obtained from 5-week-old wild type and SULTR3 quintuple plants grown on soil under short-day conditions and treated for 180 min with the effectors dissolved in water at pH 5.5. Scale bar = 10 μm. B, Stomatal aperture measured for the treatments in (A). Values are means ± se (n ≥ 60 stomata, derived from ≥ 6 individual plants). Letters indicate statistically significant differences between groups determined with the one-way repeated measure ANOVA (P < 0.001).