Plant Cell Monogr (9)
D.P.S. Verma and Z. Hong: Cell Division Control in Plants
DOI 10.1007/7089_2007_137/Published online: 25 July 2007
©Springer-Verlag Berlin Heidelberg 2007
Coordination of Cell Division and Differentiation
Crisanto Gutierrez
Centro de Biologia Molecular “Severo Ochoa”, Consejo Superior de Investigaciones,
Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
[email protected]
AbstractCell division is a highly regulated process in individual cells. Multicellularity has
introduced extra layers of regulatory complexity since maintenance of a strict cellular
homeostasis is crucial for proper development. In the case of plants, where organogenesis
is a post-embryonic and continuous process, the coordination between cell prolifera-
tion and cell differentiation is of primary importance. The last 10 years have witnessed
an unprecedented advance in our understanding of cell division and how it integrates
with differentiation and development. These studies have benefited enormously from the
availability of the full genome sequence ofArabidopsis thalianaand the genomic tools
generated. We now face the challenge to integrate the functional relationships of cell cycle
regulators into common pathways and to define the complex transcriptional networks
that coordinate cell proliferation and cell differentiation during plant development.
1
Introduction
Progression through the cell division cycle requires duplication of the genetic
material and the delivery of the newly duplicated genomes to the two daughter
cells during mitosis. However, an important consideration is that the cell cycle,
as we normally understand it, is indeed the functional integration of multiple
cycles (Fig. 1). Thus, cells develop a “growth cycle” during which they increase
in total mass, a process that largely occurs in an almost continuous man-
ner. They also develop a “DNA replication cycle”, which is a discrete process
whose duration defines the S-phase. In other words, in a population of asyn-
chronously proliferating cells, only a proportion of them is, at a given time,
engaged in duplicating their genome. During the “chromosome segregation
and cytokinesis cycle” the duplicated genome is transferred to the daughter
cells and it defines the mitotic phase, which includes cytokinesis. More recent
molecular and biochemical studies are serving to establish the occurrence of
other cycles, e.g., the “CDK cycle”, which is defined by a succession of periods
with high (from just before the S-phase until the end of metaphase) and low
(from anaphase to late G1) CDK activity. The temporal superimposition of
these functional cycles in a particular proliferating cell originates what we de-
fine as a cell cycle with the typical G1, S, G2 and M phases, although the rest of
functional activities should also be taken into account (Fig. 1).