Auxin reflux between the endodermis and pericycle promotes lateral root initiation

Authors

  • Peter Marhavý,

    1. Department of Plant Systems Biology, VIB, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
    Search for more papers by this author
    • These authors contributed equally to this work
  • Marleen Vanstraelen,

    Corresponding author
    1. Department of Plant Systems Biology, VIB, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
    Search for more papers by this author
    • These authors contributed equally to this work
  • Bert De Rybel,

    1. Department of Plant Systems Biology, VIB, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
    3. Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
    Search for more papers by this author
  • Ding Zhaojun,

    1. Department of Plant Systems Biology, VIB, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
    Search for more papers by this author
    • Present address: The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Shanda Nanlu 27, Jinan 250100, China
  • Malcolm J Bennett,

    1. Centre for Plant Integrative Biology, School of Biosciences, Centre for Plant Integrative Biology, University of Nottingham, Nottingham, UK
    Search for more papers by this author
  • Tom Beeckman,

    1. Department of Plant Systems Biology, VIB, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
    Search for more papers by this author
  • Eva Benková

    Corresponding author
    1. Department of Plant Systems Biology, VIB, Gent, Belgium
    2. Department of Plant Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
    Search for more papers by this author
    • Present address: Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria

Abstract

Lateral root (LR) formation is initiated when pericycle cells accumulate auxin, thereby acquiring founder cell (FC) status and triggering asymmetric cell divisions, giving rise to a new primordium. How this auxin maximum in pericycle cells builds up and remains focused is not understood. We report that the endodermis plays an active role in the regulation of auxin accumulation and is instructive for FCs to progress during the LR initiation (LRI) phase. We describe the functional importance of a PIN3 (PIN-formed) auxin efflux carrier-dependent hormone reflux pathway between overlaying endodermal and pericycle FCs. Disrupting this reflux pathway causes dramatic defects in the progress of FCs towards the next initiation phase. Our data identify an unexpected regulatory function for the endodermis in LRI as part of the fine-tuning mechanism that appears to act as a check point in LR organogenesis after FCs are specified.

Ancillary