VESICLE DYNAMICS DURING CELL-PLATE FORMATION IN PLANTS

Plant cells undergoing cytokinesis (cytoplasmic division) form a cell plate in the center of the phragmoplast. The phragmoplast consists of both cytoskeletal and membranous elements. The cytoskeletal elements a re required for the delivery of vesicles to the equatorial region of t he cell and provide guidance to the cell plate. Vesicles, originating from the Golgi apparatus, travel along microtubules and fuse in a uniq ue manner at the center of the phragmoplast to give rise to the new pl asma membranes of the two daughter cells. The cargo they carry contrib utes to the cell-plate matrix. The production, delivery and fusion of these vesicles at an appropriate time and place are critical for the c orrect positioning of the forming cell-plate. Recent evidence suggests that a dynamin-like protein - phragmoplastin - may be involved in 'sq ueezing' the cell-plate vesicles into specialized tubular structures, facilitating membrane fusion and the release of the vesicle contents. We describe the dynamics of this complex pathway and our progress in u nderstanding it at the molecular level.