| Effects of Brefeldin A on pollen germination and tube growth: antagonistic effects on endocytosis and secretion |
| Wang Q, Kong L, Li Y, Šamaj J, Baluška F, Lin J |
| Plant Physiol 139, 1692-1703 (2005) |
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| We assessed the effects of Brefeldin A (BFA) on pollen tube development of Picea meyeri using FM4-64 as a membrane-inserted endocytic/recycling marker together with ultrastructural observation and Fourier transform infrared (FTIR) analysis. BFA inhibited pollen germination and pollen tube growth causing morphological changes in a dose-dependent manner. FM4-64 labeling showed a typical bright apical staining in normally growing Picea meyeri pollen tubes, while this apical staining pattern was rapidly lost in the presence of BFA. In contrast, the overall uptake of FM4-64 dye was about twofold over the control after BFA (5 µg mL-1) treatment, revealing that BFA stimulated endocytosis. Transmission electron microscopic (TEM) observation showed that the number of secretory vesicles at the apical zone dramatically decreased together with the disappearance of Paramural bodies, while the number of vacuoles and other larger organelles increased. Acid phosphatase assay (acPase) confirmed that the addition of BFA significantly inhibited secretory pathways. Importantly, FTIR microspectroscopy documented significant changes in the chemical composition of pollen tube walls that was grown in the presence of BFA. These results suggest that the inhibition of polysaccharide synthesis/delivery and protein packaging of the cell wall is caused by the effect of BFA on endocytosis and secretory pathways during pollen development, inhibiting the pollen tube growth. |
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