Fig. 1.

Cytosolic malate at 1 mM activates ionic currents in Arabidopsis thaliana wild-type (WT) guard cells, whereas 0.1 mM did not significantly enhance ion currents in these experiments and 10 mM malate showed no activation of currents. (a) Typical whole-cell recordings of ionic currents in guard cell protoplasts of wild type plants without malate or with 0.1 mM, 1 mM and 10 mM malate added to the pipette solution that dialyzes the cytosol of guard cells. (b) Steady state current-voltage relationships recorded as in (a). The number of guard cells was n = 5–8 for each condition. Data are mean ± SE (One-way ANOVA and Tukey’s test: P < 0.01 for WT vs WT+1 mM malate; P < 0.01 for WT+10 mM malate vs WT+1 mM malate; P < 0.05 for WT+0.1 mM malate vs WT+1 mM malate at −145 mV).