Abstract
A phragmoplast, a cytokinetic apparatus in plant cells, builds a cell plate during cytokinesis. Formation of new microtubules at the outer margin of the phragmoplast is essential for expansion of the cell plate. We successfully observed microtubule dynamics of the outer margin of the phragmoplasts in living tobacco BY-2 cells expressing either GFP-α-tubulin, a microtubule marker, or GFP-EB1, a microtubule plus end marker. New microtubules initiated at the side of phragmoplast microtubules, elongated outside of the microtubule mass of the phragmoplast towards an equitorial plane and finally incorporated into outermost margin of the phragmoplast.
