THE PLANT CELL, Vol 2, Issue 12 1273-1282, Copyright © 1990 by American Society of Plant Biologists
Rearrangements of Microtubules Involved in Establishing Cell Division Planes Start Immediately after DNA Synthesis and Are Completed just before Mitosis
BES. Gunning and M. Sammut
Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, P.O. Box 475, Canberra City, ACT 2601, Australia
This work concerns an aspect of spatial regulation of cell division, the
development of the preprophase band (PPB) of microtubules. The PPB is
significant in plant development because its position in the dividing cell
indicates where the new cell wall will be inserted[mdash]an important site
for control of histogenesis. We have categorized and determined the
durations of stages in the development of PPBs, and have established their
timing relative to the S-, G2-, and mitotic phases of the cell cycle. Roots
of wheat seedlings were supplied with bromodeoxyuridine in continuous and
pulse-chase treatments. Cells that were in the S-phase were identified and
changes in their microtubule arrays were monitored by double
immunolabeling. PPB initiation was detectable as early as the end of the
S-phase as a narrowing of the preceding interphase array of microtubules.
Development continued throughout G2 to a mature, narrow PPB, which existed
only briefly and then eroded during the transition to the prophase mitotic
spindle. The microtubule rearrangements of PPB development showed that
preparation of the future site and plane of division in higher plant cells
begins just after DNA replication and is completed just before mitosis.
