Abstract
The preprophase band (PPB) of plants is a band of microtubules that underlies the plasma membrane in prophase cells. The PPB plays an important role in the determination of the site of division site of plant cells. Clathrin-coated vesicles (CCV) as well as structurally related non-coated vesicles (NCV) were frequently observed at the PPB. To understand the role of the vesicles and actin in PPB development, we have quantitatively analyzed the effects of cytochalasin D on the distribution and the morphology of these vesicles and of cytoskeletal structure in high-pressure frozen onion epidermal cells by electron tomography. The average size of the NCVs decreased by treatment with cytochalasin D, suggesting a role of actin in vesicle fusion. Cytochalasin D also affected MT organization in the PPB. In particular, the PPBs become wider, due to greater lateral separation of the MTs, and simultaneously the length of the average MT decreases.
