Figure 5.

SI stimulates a conductance that is highly permeable to K⁺. SI was induced by the addition of PrsS₃ + PrsS₈ to pollen protoplasts (haplotype S₃ or S₈), bathed in K⁺-containing saline. A, Representative ramp-induced, whole-cell currents obtained in an untreated pollen protoplast bathed in K⁺-containing saline before (UT; black trace) and after SI induction (SI; gray trace) by PrsS addition. The dotted line shows zero current. B, I-V curve for SI-induced current in protoplasts bathed in K⁺-containing saline (mean ± se; n = 4). C, SI-induced current in K⁺-containing medium, as in A, but with K⁺ in the backfill, internal solution. The ramp protocol was applied under control conditions in untreated (UT) protoplasts and after application of incompatible PrsS (SI). D, I-V curve for the SI-induced K⁺ current for protoplasts with K⁺ in the backfill (mean ± se; n = 3).