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  • The EMBO Journal (2003) 22, 3314 - 3325
  • doi:10.1093/emboj/cdg335

Arabidopsis AXR6 encodes CUL1 implicating SCF E3 ligases in auxin regulation of embryogenesis

Hanjo Hellmann1,2, Lawrence Hobbie3, Anngela Chapman3, Sunethra Dharmasiri1,4, Nihal Dharmasiri1,4, Carlos del Pozo1,5, Didier Reinhardt6 and Mark Estelle1,4

  1. Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
  2. Present address: Institut für Angewandte Genetik, Freie Universität Berlin, Berlin, Germany
  3. Adelphi University, Department of Biology, Garden City, NY 11530, USA
  4. Present address: Department of Biology, Indiana University, Bloomington, IN 47405, USA
  5. Present address: Centro de Biologia Molecular 'Severo Ochoa', Universidad Autonoma de Madrid, Campus de Cantoblanco, Madrid 28049, Spain
  6. Institute of Plant Sciences, University of Bern, Bern, Switzerland

Correspondence to:

Mark Estelle, E-mail: mestelle@bio.indiana.edu

Received 17 February 2003; Accepted 15 May 2003; Revised 14 May 2003

The AXR6 gene is required for auxin signaling in the Arabidopsis embryo and during postembryonic development. One of the effects of auxin is to stimulate degradation of the Aux/IAA auxin response proteins through the action of the ubiquitin protein ligase SCFTIR1. Here we show that AXR6 encodes the SCF subunit CUL1. The axr6 mutations affect the ability of mutant CUL1 to assemble into stable SCF complexes resulting in reduced degradation of the SCFTIR1 substrate AXR2/IAA7. In addition, we show that CUL1 is required for lateral organ initiation in the shoot apical meristem and the inflorescence meristem. These results indicate that the embryonic axr6 phenotype is related to a defect in SCF function and accumulation of Aux/IAA proteins such as BDL/IAA12. In addition, we show that CUL1 has a role in auxin response throughout the life cycle of the plant.

  • Keywords:

    • Arabidopsis,
    • auxin,
    • cullin,
    • IAA,
    • SCF