Stomatal Aperture Bioassay

The assay was conducted as recently described (Batool et al., 2018). Epidermal strips were peeled off the abaxial side of wild-type and quintuple mutant leaves and floated on distilled water for 2 h under constant light. The strips were then transferred to distilled water (pH 5.5) supplemented without (control) or with effectors (15 mM MgSO₄, 0.5 mM Cys, 0.5 mM Gly, and 50 μM ABA) for 3 h. Stomata were imaged before and after treatment with a conventional wide-angle microscope (Leica DMIRB). Each experiment was performed at least in triplicate and showed the same results.