THE PLANT CELL, Vol 5, Issue 12 1711-1723, Copyright © 1993 by American Society of Plant Biologists
cdc2a Expression in Arabidopsis Is Linked with Competence for Cell Division
A. S. Hemerly, P. Ferreira, J. de Almeida Engler, M. Van Montagu, G. Engler and D. Inze
Laboratorium voor Genetica, Universiteit Gent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium
A key regulator of the cell cycle is a highly conserved protein kinase
whose catalytic subunit, p34cdc2, is encoded by the cdc2 gene. We studied
the control of the expression of the Arabidopsis cdc2a gene in cell
suspensions and during plant development. In cell cultures, arrest of the
cell cycle did not significantly affect cdc2a mRNA levels, but nutrient
conditions were important for cdc2a expression. During plant development,
the pattern of cdc2a expression was strongly correlated with the cell
proliferation potential. The effects of external signals on cdc2a
expression were analyzed. Wounding induced expression in leaves. Lack of
light altered temporal regulation of cdc2a in the apical but not root
meristem of seedlings. Differential cdc2a responses were obtained after
different hormone treatments. Signals present only in intact plants were
necessary to mediate these responses. Although other control levels have
yet to be analyzed, these results suggest that the regulation of cdc2a
expression may contribute greatly to spatial and temporal regulation of
cell division in plants. Our results also show that cdc2a expression is not
always coupled with cell proliferation but always precedes it. We propose
that cdc2a expression may reflect a state of competence to divide, and that
the release of other controls is necessary for cell division to occur.
