Arabidopsis TCP20 links regulation of growth and cell division control pathways

doi:10.1073/pnas.0504039102

Arabidopsis TCP20 links regulation of growth and cell division control pathways

^*Institute for Molecular Plant Science, School of Biological Sciences, University of Edinburgh, EH9 3JR Edinburgh, Scotland; ^§Plant Biology Laboratory, Salk Institute for Biological Studies, 10100 North Torrey Pines Road, La Jolla, CA 92037; and ^∥Department of Biology, New York University, 100 Washington Square East, 1009 Main Building, New York, NY 10003

Edited by Elliot M. Meyerowitz, California Institute of Technology, Pasadena, CA, and approved July 15, 2005 (received for review May 15, 2005)

Abstract

During postembryonic plant development, cell division is coupled to cell growth. There is a stringent requirement to couple these processes in shoot and root meristems. As cells pass through meristems, they transit through zones with high rates of cell growth and proliferation during organogenesis. This transition implies a need for coordinate regulation of genes underpinning these two fundamental cell functions. Here, we report a mechanism for coregulation of cell division control genes and cell growth effectors. We identified a GCCCR motif necessary and sufficient for high-level cyclin CYCB1;1 expression at G₂/M. This motif is overrepresented in many ribosomal protein gene promoters and is required for high-level expression of the S27 and L24 ribosomal subunit genes we examined. p33^TCP20, encoded by the Arabidopsis TCP20 gene, binds to the GCCCR element in the promoters of cyclin CYCB1;1 and ribosomal protein genes in vitro and in vivo. We propose a model in which organ growth rates, and possibly shape in aerial organs, are regulated by the balance of positively and negatively acting teosinte-branched, cycloidea, PCNA factor (TCP) genes in the distal meristem boundary zone where cells become mitotically quiescent before expansion and differentiation.

Footnotes

↵ ** To whom correspondence should be addressed. E-mail: peter.doerner{at}ed.ac.uk.
↵ † Present address: Plant Sciences Department, University of California, Davis, CA 95616.
↵ ‡ Present address: Institut de Biologie Moléculaire des Plantes, 12 Rue du Général Zimmer, 67084 Strasbourg, France.
↵ ¶ Present address: University of Massachusetts, Boston, MA 02125.
Author contributions: C.L., T.P., A.C.-C., and P.D. designed research; C.L., T.P., A.C.-C., and P.D. performed research; R.A.G. contributed new reagents/analytic tools; C.L., T.P., A.C.-C., R.A.G., and P.D. analyzed data; and P.D. wrote the paper.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations: TCP, teosinte-branched, cycloidea, PCNA factor; ChIP, chromatin immunoprecipitation; RP, ribosomal protein.