hca: an Arabidopsis mutant exhibiting unusual cambial activity and altered vascular patterning

Authors

  • Christophe Pineau,

    1. Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique – Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, 31326 Castanet Tolosan, France,
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  • Amandine Freydier,

    1. Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique – Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, 31326 Castanet Tolosan, France,
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  • Philippe Ranocha,

    1. Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique – Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, 31326 Castanet Tolosan, France,
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  • Alain Jauneau,

    1. Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique – Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, 31326 Castanet Tolosan, France,
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  • Simon Turner,

    1. School of Biological Sciences, The University of Manchester, 3.614 Stopford Building, Oxford Road, Manchester M13 9PT, UK,
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  • Gaëtan Lemonnier,

    1. INRA/CNRS – URGV 2, rue Gaston Crémieux, CP5708, 91057 Evry Cedex, France,
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  • Jean-Pierre Renou,

    1. INRA/CNRS – URGV 2, rue Gaston Crémieux, CP5708, 91057 Evry Cedex, France,
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  • Petr Tarkowski,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, SLU, SE-901 83 Umeå, Sweden, and
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    • Present address: Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71, Olomouc, Czech Republic.

  • Göran Sandberg,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, SLU, SE-901 83 Umeå, Sweden, and
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  • Lise Jouanin,

    1. Laboratoire de Biologie Cellulaire, INRA, 78026 Versailles Cedex, France
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  • Björn Sundberg,

    1. Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, SLU, SE-901 83 Umeå, Sweden, and
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  • Alain-Michel Boudet,

    1. Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique – Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, 31326 Castanet Tolosan, France,
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  • Deborah Goffner,

    1. Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique – Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, 31326 Castanet Tolosan, France,
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  • Magalie Pichon

    Corresponding author
    1. Surfaces Cellulaires et Signalisation chez les Végétaux, Unité Mixte de Recherche, Centre National de la Recherche Scientifique – Université Paul Sabatier 5546, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, 31326 Castanet Tolosan, France,
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(fax +33 562 193 502; e-mail pichon@scsv.ups-tlse.fr).

Summary

By screening a T-DNA population of Arabidopsis mutants for alterations in inflorescence stem vasculature, we have isolated a mutant with a dramatic increase in vascular tissue development, characterized by a continuous ring of xylem/phloem. This phenotype is the consequence of premature and numerous cambial cell divisions in both the fascicular and interfascicular regions that result in the loss of the alternate vascular bundle/fiber organization typically observed in Arabidopsis stems. The mutant was therefore designated high cambial activity (hca). The hca mutation also resulted in pleiotropic effects including stunting and a delay in developmental events such as flowering and senescence. The physiological characterization of hca seedlings in vitro revealed an altered auxin and cytokinin response and, most strikingly, an enhanced sensitivity to cytokinin. These results were substantiated by comparative microarray analysis between hca and wild-type plants. The genetic analysis of hca indicated that the mutant phenotype was not tagged by the T-DNA and that the hca mutation segregated as a single recessive locus, mapping to the long arm of chromosome 4. We propose that hca is involved in mechanisms controlling the arrangement of vascular bundles throughout the plant by regulating the auxin–cytokinin sensitivity of vascular cambial cells. Thus, the hca mutant is a useful model for examining the genetic and hormonal control of cambial growth and differentiation.

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