Fig. 3. Exogenous H₂O₂ rescues stomatal closing in atrbohD/F double mutant. H₂O₂ induces stomatal closing both in atrbohD/F and WT. Stomatal apertures were measured 3 h after addition of 100 or 500 µM H₂O₂. n = 3 experiments (60 stomatal apertures) for WT; n = 3 experiments (60 stomatal apertures) for atrbohD/F. Starting stomatal apertures: 3.81 ± 0.20 µm (WT), 3.40 ± 0.04 µm (atrbohD/F). Error bars represent ± SEM relative to three independent experiments. Error bars are smaller than symbols when not visible.