Figure 8.

Whole-Vacuole Recordings of Currents Triggered by myo-Inositol in Mesophyll Vacuoles of INT1 Wild-Type and int1 Mutant Plants.

(A) The stylized presentation of vacuoles with attached patch pipettes shows the experimental conditions in the absence (gray bars) or presence (black bars) of myo-inositol in the bath medium. Cytosolic application of 50 mM myo-inositol (black bars) resulted in INT1-mediated H⁺ currents into the vacuoles of wild-type plants, as represented by the upward deflection of the current traces. Under the same experimental conditions, no or significantly smaller myo-inositol–induced H⁺ currents were observed in int1.1 or int1.2 mutant plants, respectively. Note that INT1-dependent currents were determined in the inverse mode (i.e., pH values in the extravacuolar bath and the patch pipette solution were adjusted to 5.5 and 7.5, respectively).

(B) Similar measurement as in (A), but with 50 mM glucose on vacuoles from wild-type and int1.1 mutant plants.

(C) Average currents calculated from several experiments (n = 3; ±sd) performed under identical conditions as the original recordings shown in (A) and (B). Reproducibly, inositol induced no current (= 0 pA/pF) in vacuoles of int1.1 plants.