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  • The EMBO Journal (2002) 21, 6036 - 6049
  • doi:10.1093/emboj/cdf614

Cell numbers and leaf development in Arabidopsis: a functional analysis of the STRUWWELPETER gene

Daphné Autran1,4, Claudia Jonak2,4, Katia Belcram1, Gerrit T. S. Beemster3, Jocelyne Kronenberger1, Olivier Grandjean1, Dirk Inzé3 and Jan Traas1

  1. Laboratoire de Biologie Cellulaire, INRA, Route de Saint-Cyr, 78026 Versailles cedex, France
  2. Institute of Microbiology and Genetics, Vienna Biocenter, University of Vienna, Dr Bohrgasse 9, 1030 Vienna, Austria
  3. Department of Plant Systems Biology, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium
  4. D.Autran and C.Jonak contributed equally to this work

Correspondence to:

Jan Traas, E-mail: Jan.Traas@versailles.inra.fr

Received 10 January 2002; Accepted 26 September 2002; Revised 17 June 2002

The struwwelpeter (swp) mutant in Arabidopsis shows reduced cell numbers in all aerial organs. In certain cases, this defect is partially compensated by an increase in final cell size. Although the mutation does not affect cell cycle duration in the young primordia, it does influence the window of cell proliferation, as cell number is reduced during the very early stages of primordium initiation and a precocious arrest of cell proliferation occurs. In addition, the mutation also perturbs the shoot apical meristem (SAM), which becomes gradually disorganized. SWP encodes a protein with similarities to subunits of the Mediator complex, required for RNA polymerase II recruitment at target promoters in response to specific activators. To gain further insight into its function, we overexpressed the gene under the control of a constitutive promoter. This interfered again with the moment of cell cycle arrest in the young leaf. Our results suggest that the levels of SWP, besides their role in pattern formation at the meristem, play an important role in defining the duration of cell proliferation.

  • Keywords:

    • leaf development,
    • Mediator complex,
    • primordia,
    • shoot apical meristem