Effects of the microtubulo inhibitor Nocodazole on endocytosis in pollen tubes of Nicotianan tabacum

The pollen tube is a highly polarized cell, it was generally accepted that secretory vesicles (SVs) are transported by the acto-myosin system to the tip region where they are accumulated in the clear zone. Recently, use of lypophilic dyes and analysis of vesicle dynamic suggest a new model of growth that the apical PM is not only the site of exocytosis but the endocytic vesicles significantly contribute to the V-shaped vesicle accumulation in addition to SVs. In this study we disturb the system of Mts using low concentration of Nocodazole, to verify modifications in endocytosis and endosome trafficking. Our results demonstrated that the perturbation of Mts had not influence on the distribution of the Afs and in the internalization of PM both in subapical and in the apical regions. Colocalization experiments using dyes for Golgi, acidic compartments and FM4-64 in vivo assays revealed that Mts play a role in the transport of endosomes internalized in the tip region. These data have been also confirmed by ultrastructural observations of negatively charged naogold, whose transport to vacuoles appeared to be retarded with nocodazole