Abstract
How plant microtubules assemble at the cell cortex is one of central importance for understanding cell morphogenesis, because interphase cortical microtubules control the direction of cell growth, and G2 and prophase microtubules assemble as a preprophase band (PPB) to predict the future division site. Actin is thought to be involved in the architecture of microtubule structure. We have quantitatively analyzed the microtubule and microfilaments architecture in cell cortex of epidermal cells of high pressure frozen onion cotyledons visualized by dual-axis electron tomography (7 nm 3-D resolution). Our tomogram images clearly show that existence of actin-depleted zone at mature PPB stage, but the actin-depleted zone disappear and the co-localization of microfilaments with PPB microtubules is seen in the cytochalasin D-treated cells. This electron microscopic techniques also have enabled us to identify several types of microtubule end structures, such as capped end, coiled end, blunt end and open sheet.
