Figure 7.

S-Type Anion Channel Activation by [Ca²⁺]_cyt- and [Ca²⁺]_ext-Induced Stomatal Closure Is Not Impaired in the era1-2 abi2-1 Double Mutant.

(A) S-type anion channel currents in era1-2 abi2-1 double mutant guard cell protoplasts preincubated in 40 mM [Ca²⁺]_ext with [Ca²⁺]_cyt buffered to 500 nM (left) and 2 μM (right).

(B) Current-voltage relationships for S-type anion currents recorded from wild-type (closed circles), era1-2 (open circles), or era1-2 abi2-1 double mutant (closed squares) guard cell protoplasts preincubated in 40 mM [Ca²⁺]_ext with [Ca²⁺]_cyt buffered at 2 μM (right) or 500 nM (left) as in (A). The wild-type and era1-2 data are as presented in Figures 4C and 4D and are shown for direct comparison with era1-2 abi2-1 data.

(C) [Ca²⁺]_ext-induced stomatal closure in the wild type (closed circles), era1-2 (closed triangles), and era1-2 abi2-1 double mutant (open squares). Note that stomata were opened in buffer containing 5 mM KCl and no CaCl₂, pH 6.15, and that in the absence of [Ca²⁺]_ext, era1-2 and era1-2 abi2-1 double mutant stomates failed to open to the same aperture as the wild type. Data are means ± sem relative to three replicates comprising 120 stomates per point.

mCol, Columbia.