Figure 7.

Ca²⁺ ionophore A23187 triggers cytosolic acidification and vacuolar reorganization of field poppy pollen tubes. A, Fifty micromolar A23187 (black symbols; n = 27) or growth medium (white symbols; n = 25) was added to field poppy pollen tubes growing in vitro, and pH was measured and calibrated with the ratiometric pH indicator BCECF AM. B, Pollen tubes were treated with 10 µm A23187 and labeled with carboxy-DCFDA to visualize the vacuole. Numbers indicate the length of treatment time in minutes: 7 min after the addition of A23187, the vacuole still shows some reticulate appearance; 25 min after the addition of A23187, there is major reorganization with appearance of collapse/aggregation; 46 min after the addition of A23187, little structure is apparent; and 77 min after the addition of A23187, reduced signal suggests extensive breakdown of the vacuole. UT, Typical untreated pollen tube exhibits a reticulate structure. Bar = 10 µm.