Abstract
Cortical microtubules are essential cytoskeletal elements that decide the direction of cell expansion by the modulation of the orientation of cellulose microfibrils. Although the cortical microtubules disappear in early M-phase and reorganizes in early G1-phase, this reorganizing system is still unclear. So we prepared a transgenic tobacco BY-2 cell line, which expresses GFP-fused EB1 proteins, The EB1 proteins localized the plus end of the elongating microtubules and the microtubule elongation could be traced. In this cell line, we found that the cortical microtubules largely elongated to the cell end but their orientations were not parallel in the early phase of the cortical microtubule reorganization. A comparable result was observed during the cortical microtubule reorganization in mini-protoplasts in which vacuoles were removed from protoplasts, and the cortical microtubules were disappeared. Now we are examining the cortical microtubule reorganization quantitatively by programming a software, which can trace the EB1 protein movement.
