Figure 6.
Stomatal closure response under drought. (a) Stomatal apertures in SF-primed and unprimed plants with the progression of drought stress. Note that, under well-watered conditions, SF priming (SF+H2O) leads to partial stomatal closure compared to nonprimed plants (H2O+H2O). Under conditions of drought stress, partial stomatal closure occurred earlier in SF-primed plants (SF+Dr) than in nonprimed plants (H2O+Dr). Error bars indicate standard error of the mean (SEM), n ≥ 250; treatments sharing different letters indicate significant differences from each other (p < 0.05; one-way ANOVA, Tukey’s multiple comparison test). (b) Relative expression of PRX34 in SF-primed and unprimed plants. Values are expressed as fold change (FC) in expression normalized to those determined in unprimed, well-watered (H2O+H2O) controls. Asterisks represent significant differences in expression in unprimed drought-stressed (H2O+Dr) vs. primed (SF+Dr and SF+H2O) plants (p < 0.0001; one-way ANOVA, Tukey’s multiple comparison test). (c) Histochemical staining assay for ROS accumulation in leaf stomata. Leaf epidermal peels from plants (unprimed and primed) under drought stress were used for DAB staining following a reported protocol [74]. Red arrow heads indicate stomata. Dr, drought stress; SF, Super Fifty.