Plant Cell Monogr (9)
D.P.S. Verma and Z. Hong: Cell Division Control in Plants
DOI 10.1007/7089_2007_119/Published online: 11 July 2007
©Springer-Verlag Berlin Heidelberg 2007
Circadian Regulation of Cell Division
François-Yves Bouget () · Mickael Moulager · Florence Corellou
UMR 7628 CNRS, Université Paris VI, Laboratoire Arago,
Modèles en Biologie Cellulaire et Evolutive, BP44, 66651 Banyuls sur Mer, France
[email protected]
AbstractPlants are photosynthetic organisms, which use light, as main source of energy,
for growth and development. Because sun-light is also mutagenic, many organisms, from
most kingdoms, have evolved an internal time-tracking system, so-called the circadian,
which restricts cell division to specific times of the day in when DNA is less exposed to
UV damage (“escape from mutagenic light” theory). While the circadian regulation of cell
division has been extensively characterized in animals and unicellular green algae, little is
known about the photoperiodic regulation of cell division in land plants. Recent findings
about the possible links between cell division, the circadian clock and the DNA damage
checkpoint are discussed.
1
Introduction
Biological clocks are pacemakers, which play an essential role in regulating
the physiology and behavior of living organisms. Such clocks are the cell di-
vision cycle (CDC) and the circadian clock, which coexist in many cells from
organisms including plants, animals, fungi and cyanobacteria (Bell-Pedersen
et al. 2005; McClung 2006; Naef 2005). Each day, living organisms are exposed
to changes in light (photoperiod) and temperature due to the rotation of the
earth. Furthermore the relative day to night lengths vary along the year. The
circadian clock is an autonomous system, which gives the time and can be
entrained by light or temperature cycles. This clock allows the organism to
adapt to the predictable daily environmental changes by anticipating them.
The first evidence of a circadian clock was first demonstrated in 1729 by de
Mairan, who showed that a heliotrop plant still exhibits robust rhythms of leaf
movement when placed in constant darkness. Since then, the circadian clock
was shown to regulate a wide array of plant physiology processes including
photosynthesis, metabolism, and at the molecular level, a significant propor-
tion of gene expression (Gardner et al. 2006). The circadian clock is likely
to confer an adaptive advantage to multicellular organisms since it is found
in all kingdoms including animals, plants and fungi. Among unicellular free-
living organisms circadian rhythms have been described almost exclusively in
photosynthetic ones.