Plant Cell Monogr (9)
D.P.S. Verma and Z. Hong: Cell Division Control in Plants
DOI 10.1007/7089_2007_122/Published online: 31 July 2007
©Springer-Verlag Berlin Heidelberg 2007
G1/S Transition and the Rb-E2F Pathway
We n - Hu i S h e n
Institut de Biologie Moléculaire des Plantes (IBMP),
Centre National de la Recherche Scientifique (CNRS),
Université Louis Pasteur de Strasbourg (ULP),
12 rue du Général Zimmer, 67084 Strasbourg, France
[email protected]
AbstractThe G1/S transition appears central to the commitment to further cell division
or differentiation in eukaryotic cells. The highly regulated G1/S transition requires the
concerted action of specific cyclin-CDK kinases on specific target proteins. In plants as
in animals, the Rb-E2F pathway represents the major target, its activation triggers tran-
scription of a battery of genes involved in cell cycle control, DNA replication and cell
metabolism. Recent molecular and genetic studies uncovered critical roles of the G1/S
cell-cycle machinery and the Rb-E2F pathway in cell division and differentiation, bring-
ing the cell cycle control in the context of plant growth and development. Correct and
complete execution of DNA replication and packaging into chromatin not only ensures
integral transmission of genetic information during cell division but also affects genome
transcription.
1
Introduction
The cell division cycle proceeds in a highly ordered manner, which is driven
by control systems at regulatory transitions named checkpoints. The check-
point at the G1/S transition is called “Start” in yeast and “Restriction point”
in animals. Once cells have passed this checkpoint, they become insensi-
tive to external signals and undergo a complete cell cycle until they reach
the next G1 phase. In unicellular algae, cell size and light-dependent restric-
tion points at G1 have been documented (Hagiwara et al. 2001; Umen et al.
2001). In higher plants, application of chemical inhibitors reveals a crucial
point of control in the G1 phase which commits cell division or differenti-
ation (Planchais et al. 1997; Mourelatou et al. 2004). Because of its critical
importance, the G1/S transition attracts particular attention in plant cell
cycle research (Shen 2001; Gutierrez et al. 2002; Oakenfull et al. 2002; Rossi
and Varotto 2002; Shen 2002). In this chapter, I will discuss recent research
progress on the cell cycle machinery operating at the G1/S transition, the
downstream Rb-E2F pathway, and also DNA and chromatin replication in
higher plants.