Fig. 5: Guard cell photosynthesis induces Thr-881 phosphorylation.

a, b Red light-dependent phosphorylation of Thr-881. Guard cell protoplasts were incubated in the dark for 30 min or illuminated with red light (RL: 300 μmol m⁻² s⁻¹) for 30 min, after which a pulse of blue light (BL: 100 μmol m⁻² s⁻¹, 30 s) was superimposed on RL. c, d Effect of the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) on Thr-881 phosphorylation. Guard cell protoplasts were pre-treated with DCMU (10 µM) in the dark for 30 min. e–j Red light-dependent phosphorylation of Thr-881 in the phot1-5 phot2-1 (e, f), blus1-1 (g, h), and the T948A line (i, j). For (b), (d), (f), (h), and (j), the relative phosphorylation levels of Thr-881 and Thr-948 were quantified using the ImageJ software. The data represent means ± SD (n = 3 biologically independent experiments). Different letters indicate significant differences, One-way ANOVA with Tukey’s test, P < 0.01 for (b), (f), and (h) and P < 0.05 for (d) and (j).