Expression of TWISTED DWARF1 lacking its in-plane membrane anchor leads to increased cell elongation and hypermorphic growth

Authors

  • Aurélien Bailly,

    1. Department of Biology – Plant Biology, University of Fribourg, Fribourg, Switzerland
    2. Institute of Plant Biology, University of Zurich, Zurich, Switzerland
    Current affiliation:
    1. Institute for Plant Biology, Department of Microbiology, University of Zurich, Zurich, Switzerland
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  • Bangjun Wang,

    1. Department of Biology – Plant Biology, University of Fribourg, Fribourg, Switzerland
    2. Institute of Plant Biology, University of Zurich, Zurich, Switzerland
    3. Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
    Current affiliation:
    1. School of Life Sciences, Southwest University, Chongqing, China
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  • Marta Zwiewka,

    1. Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), Brno, Czech Republic
    2. Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
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  • Stephan Pollmann,

    1. Ruhr-Universität Bochum, Lehrstuhl für Pflanzenphysiologie, Germany
    Current affiliation:
    1. Centro de Biotecnología y Genomica de Plantas, Campus de Montegancedo, Madrid, Spain
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  • Daniel Schenck,

    1. Biozentrum Klein Flottbek, Universität Hamburg, Hamburg, Germany
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  • Hartwig Lüthen,

    1. Biozentrum Klein Flottbek, Universität Hamburg, Hamburg, Germany
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  • Alexander Schulz,

    1. Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
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  • Jiri Friml,

    1. Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University (MU), Brno, Czech Republic
    2. Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
    3. Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria
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  • Markus Geisler

    Corresponding author
    1. Department of Biology – Plant Biology, University of Fribourg, Fribourg, Switzerland
    2. Institute of Plant Biology, University of Zurich, Zurich, Switzerland
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Summary

Plant growth is achieved predominantly by cellular elongation, which is thought to be controlled on several levels by apoplastic auxin. Auxin export into the apoplast is achieved by plasma membrane efflux catalysts of the PIN-FORMED (PIN) and ATP-binding cassette protein subfamily B/phosphor-glycoprotein (ABCB/PGP) classes; the latter were shown to depend on interaction with the FKBP42, TWISTED DWARF1 (TWD1). Here by using a transgenic approach in combination with phenotypical, biochemical and cell biological analyses we demonstrate the importance of a putative C-terminal in-plane membrane anchor of TWD1 in the regulation of ABCB-mediated auxin transport. In contrast with dwarfed twd1 loss-of-function alleles, TWD1 gain-of-function lines that lack a putative in-plane membrane anchor (HA–TWD1-Ct) show hypermorphic plant architecture, characterized by enhanced stem length and leaf surface but reduced shoot branching. Greater hypocotyl length is the result of enhanced cell elongation that correlates with reduced polar auxin transport capacity for HA–TWD1-Ct. As a consequence, HA–TWD1-Ct displays higher hypocotyl auxin accumulation, which is shown to result in elevated auxin-induced cell elongation rates. Our data highlight the importance of C-terminal membrane anchoring for TWD1 action, which is required for specific regulation of ABCB-mediated auxin transport. These data support a model in which TWD1 controls lateral ABCB1-mediated export into the apoplast, which is required for auxin-mediated cell elongation.

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