Figure 3.

The effect of PtdOH on guard cell cytoplasmic [Ca²⁺] and the effect of inhibitors of the ABA response on stomatal aperture. (A–D) Midplane confocal sections of guard cells microinjected with Indo-1 dextran and imaged before (A) or after 20-min incubation (B) or after 20-min treatment with 10 μM (+/−)-ABA (C) or 50 μM PtdOH (D). (E) Average cytoplasmic [Ca²⁺] determined by confocal ratio analysis of guard cells microinjected with Indo-1-dextran and treated with 10 μM (+/−)-ABA or 50 μM PtdOH as indicated. Each plot shows the mean ± SEM: control, n = 10; ABA, n = 12; PtdOH, n = 10. (F) Epidermal peels were kept in the light for 1 hr to induce stomatal opening and then treated (still in the light) as indicated. Concentrations used: (+/−)-ABA, 10 μM; 1-buOH, 0.1%; nicotinamide, 50 mM; U73122 and U73433, 1 μM. The results show the mean ± SEM of at least three independent experiments measuring at least 60 stomata on 3 separate peels.