Figure 2.

BR Acts Synergistically with ABA in Stomatal Closure.

(A) Stomatal apertures in Col-0 and cdl1 upon BR treatment. The wild type and cdl1 were treated with different concentration of BL in the stomatal closure assay. Result is representative of three independent experiments (n ≥ 40 stomata per genotype).

(B) Complementation of the BR insensitivity of cdl1 by CDL1 overexpression. The stomatal apertures in Col-0 and cdl1 expressing 35S-CDL1-YFP were compared. Result is representative of three independent experiments (n ≥ 30 stomata per genotype).

(C) Effect of BR on ABA-induced stomatal closure in wild-type Col-0. The stomatal apertures in Col-0 were measured upon ABA treatment in the absence (−BL) or presence (+BL; 0.05 μM) of BL. Result is representative of two independent experiments (n ≥ 40 stomata per genotype). Asterisk indicates statistical significant difference (paired Student’s t test, P < 0.005).

(D) Effect of BR on ABA-induced stomatal closure in the cdl1 mutant. The stomatal apertures of cdl1 were measured upon ABA treatment in the absence (−BL) or presence (+BL; 0.05 μM) of BL. Result is representative of three independent experiments (n ≥ 30 stomata per genotype). A paired Student’s t test indicated that there was no significant difference in stomatal aperture between mock and BL treatment.

(E) ABA sensitivities of wild-type Col-0 and BR-related mutants in the stomatal closure assay. Result is representative of three independent experiments (n ≥ 30 stomata per genotype).

(F) BR sensitivities of wild-type Col-0 and BR-related mutants in stomatal closure assay. Result is representative of three independent experiments (n ≥ 30 stomata per genotype).

Detached rosette leaves were incubated in stomatal closure solution containing mock, ABA, or BL as indicated for 2 h. Error bars indicate se. Except (C) and (D), statistical tests were performed by two-way ANOVA. Statistical significant differences are indicated by different lowercase letters (P < 0.005).