Figure 4.

Quantitative systems modeling (Chen et al., 2012b; Hills et al., 2012) reproduces characteristics for slac1-1 guard cells and accounts for altered K⁺ channel activities through predicted elevations of pH_i and [Ca²⁺]_i. Outputs are derived from modeling of the diurnal cycle (Chen et al., 2012b). Additional model outputs and detailed explanations are provided with Supplemental Figures S1 to S7. The full set of model parameters and initializing variables are listed in Supplemental Appendix S1 and are available with the OnGuard software at www.psrg.org.uk. A, Mean stomatal apertures and cytosolic and vacuolar solute concentrations for guard cells of stomata in the dark (closed) and light (open). Outputs are for each variable (left to right, wild-type [wt] closed and open, slac1 closed and open). B, Stomatal opening rates (left) and closure half-times (right) determined from simulated apertures during the first 3 h (opening) and the final 3 h (closing) of the daylight period (compare with Fig. 2; Supplemental Fig. S1). C and D, Current-voltage curves for I_K,out (C) and I_K,in (D) in wild-type (solid line) and slac1 (dotted line) simulations taken at 3 h into the daylight period (compare with Fig. 1, A and B). E, Predicted outputs (left to right, outputs for wild-type closed and open, slac1 closed and open) for pH_i (left), vacuolar pH (center), and [Ca²⁺]_i (right).