Non-cell autonomous regulation of life cycle transitions in the model brown alga Ectocarpus

Authors

  • Alok Arun,

    1. UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Roscoff Cedex, France
    2. The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Roscoff Cedex, France
    Search for more papers by this author
    • Joint first authors.
  • Nick T. Peters,

    1. UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Roscoff Cedex, France
    2. The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Roscoff Cedex, France
    3. Department of Biology, University of Utah, Salt Lake City, Utah, USA
    Search for more papers by this author
    • Joint first authors.
  • Delphine Scornet,

    1. UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Roscoff Cedex, France
    Search for more papers by this author
  • Akira F. Peters,

    1. UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Roscoff Cedex, France
    2. The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Roscoff Cedex, France
    3. Bezhin Rosko, Santec, France
    Search for more papers by this author
  • J. Mark Cock,

    1. UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Roscoff Cedex, France
    2. The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Roscoff Cedex, France
    Search for more papers by this author
  • Susana M. Coelho

    Corresponding author
    1. The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Roscoff Cedex, France
    • UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Roscoff Cedex, France
    Search for more papers by this author

Author for correspondence:

Susana M. Coelho

Tel: +33 298 29 23 60

Email: coelho@sb-roscoff.fr

Summary

  • The model brown alga Ectocarpus has a haploid-diploid life cycle, involving alternation between two independent multicellular generations, the gametophyte and the sporophyte. Recent work has shown that alternation of generations is not determined by ploidy but is rather under genetic control, involving at least one master regulatory locus, OUROBOROS (ORO).
  • Using cell biology approaches combined with measurements of generation-specific transcript abundance we provide evidence that alternation of generations can also be regulated by non-cell autonomous mechanisms.
  • The Ectocarpus sporophyte produces a diffusible factor that causes major developmental reprogramming in gametophyte cells. Cells become resistant to reprogramming when the cell wall is synthetized, suggesting that the cell wall may play a role in locking an individual into the developmental program that has been engaged. A functional ORO gene is necessary for the induction of the developmental switch.
  • Our results highlight the role of the cell wall in maintaining the differentiated generation stage once the appropriate developmental program has been engaged and also indicate that ORO is a key member of the developmental pathway triggered by the sporophyte factor. Alternation between gametophyte and sporophyte generations in Ectocarpus is surprisingly labile, perhaps reflecting an adaptation to the variable seashore environment inhabited by this alga.

Ancillary