Confocal imaging of N. tabacum pollen tubes expressing GFP-AtSYP121 and GFP-AtSYP122. Scale bars = 20 μm. A and B: Time-course series of growing tobacco pollen tubes transiently transformed with the GFP-SYP121 (A) and GFP-SYP122 (B) constructs (observations made ~6 h after transformation). Both proteins seem to accumulate similarly, mostly in apical vesicles and at the plasma membrane near the pollen tip. Numbers refer to the time interval (in seconds). C: Time course analysis of GFP fluorescence intensity in the growing pollen tubes shown in A and B. Imaging and measurements were performed under the same conditions and settings as in figure 1E. D: Distribution of average fluorescence intensity along the first 40 μm of the pollen tubes plasma membrane as depicted in the diagram for growing pollen tubes expressing GFP-SYP121 (dotted line; n = 9) and GFPSYP122 (solid line; n = 7). The distribution of SYP121 and SYP122 are significantly different from GFP-SYP124 (P = 9E-39 and P = 2E-25 respectively) with the region 10-25 μm behind the apex not showing the highest labelling. Error bars not displayed for the sake of clarity. E and F: Pollen tubes expressing high levels of GFP-SYP121 (E) and GFP-SYP122 (F) exhibited disturbed protein localization but no perturbations in apical morphology.