This renewal project addresses the role of the plant cytoskeleton during plant development, with emphasis on the reorganization of microtubule arrays during the life of a cell. Attention will be focussed on a system found to be advantageous in prior studies, the dividing generative cell of Tradescantia, which features what appears to be reutilization of Mts in different arrays. The questions to be addressed include the mechanism governing conversion of interphase microtubule bundles into kinetochore fibers, the manner in which kinetochore fibers and surrounding microtubules are reorganized into large superbundles during anaphase, the role of this reorganization in chromosome motion, the mechanism governing constriction cytokinesis, and the role of chromosome volume and physical constraints in the architecture of the division apparatus. Principal approaches include immunofluorescence techniques, conventional and confocal laser scanning microscopy, electron microscopy, analyses of proteins in isolated generative cells, and the use of related species of different ploidy levels. The long term goal of this work is to understand the mechanisms governing reorganization of microtubules in plant cells. Microtubules are important and dynamic structural elements in all eukaryotic cells, and are known to play significant roles in the development and maintenance of cell shape, intracellular movement of subcellular particles, and in the segregation of chromosomes during cell division.
