| Endocytosed cell surface material is used for cell plate formation during plant cytokinesis |
| Dhonukshe P, Baluška F, Hlavacka A, Schlicht M, Šamaj J, Friml J, Gadella Jr TWJ |
| Dev Cell 10, 137-150 (2006) |
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| Cytokinetic plant cells perform an amazing task of building a new cell wall within the cytoplasm in a matter of minutes that physically seperates the daughter cells. During the last four decades, the Golgi Apparatus (GA)-based secretory pathway has been considered to be the sole source for this cell plate (primordial cell wall) formation. Strikingly, our real time live cell analysis together with immunolocalization studies reveal fast delivery of internalized plasma membrane (PM) / cell wall (CW) material for cell plate formation. The PM-inserted endocytic tracer FM4-64, CW/endocytic pectins cross-linked with boron and calcium, as well as two different fluid-phase endocytosis markers, all are delivered to the forming cell plates. In addition, co-localization studies using transformed cell lines also show that fusion of endosomes coincides and colocalizes with cell plate initiation in a GA-free zone. Furthermore, fluorescence recovery after photobleaching (FRAP) analysis indicates that endocytosis continues during lateral expansion of growing cell plates. Pharmacological studies and site-directed mutagenic analyses of the endosomal Rab GTPase Ara7 confirm the requirement of the endocytic pathway for the cell plate formation. These multiple independent lines of evidence suggest that besides delivery of GA-derived material, constitutive delivery of endocytic material in form of prefabricated PM/CW material is required for cell plate-formation during plant cytokinesis. |
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