Diurnal oscillations of metabolite abundances and gene analysis provide new insights into central metabolic processes of the brown alga Ectocarpus siliculosus

Authors

  • Antoine Gravot,

    1. UMR 118 INRA, Agrocampus Ouest, Université de Rennes 1, Amélioration des Plantes et Biotechnologies Végétales, Campus de Beaulieu, bât. 14A, F-35042 Rennes Cedex, France
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    • These authors contributed equally to this work as first authors.

  • Simon M. Dittami,

    1. UPMC Univ Paris 6, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
    2. CNRS, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
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    • These authors contributed equally to this work as first authors.

  • Sylvie Rousvoal,

    1. UPMC Univ Paris 6, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
    2. CNRS, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
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  • Raphael Lugan,

    1. UMR 118 INRA, Agrocampus Ouest, Université de Rennes 1, Amélioration des Plantes et Biotechnologies Végétales, Campus de Beaulieu, bât. 14A, F-35042 Rennes Cedex, France
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  • Anja Eggert,

    1. Leibniz Institute for Baltic Sea Research Warnemünde, Physical Oceanography and Instrumentation, Seestraße 15, D-18119 Rostock, Germany
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  • Jonas Collén,

    1. UPMC Univ Paris 6, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
    2. CNRS, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
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  • Catherine Boyen,

    1. UPMC Univ Paris 6, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
    2. CNRS, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
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  • Alain Bouchereau,

    1. UMR 118 INRA, Agrocampus Ouest, Université de Rennes 1, Amélioration des Plantes et Biotechnologies Végétales, Campus de Beaulieu, bât. 14A, F-35042 Rennes Cedex, France
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  • Thierry Tonon

    1. UPMC Univ Paris 6, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
    2. CNRS, UMR 7139 Végétaux Marins et Biomolécules, Station Biologique, F-29682 Roscoff, France
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Author for correspondence:
Thierry Tonon
Tel: +33 (0) 2 98 29 23 30
Email: tonon@sb-roscoff.fr

Summary

  • Knowledge about primary metabolic processes is essential for the understanding of the physiology and ecology of seaweeds. The Ectocarpus siliculosus genome now facilitates integrative studies of the molecular basis of primary metabolism in this brown alga.
  • Metabolite profiling was performed across two light–dark cycles and under different CO2 and O2 concentrations, together with genome and targeted gene expression analysis.
  • Except for mannitol, E. siliculosus cells contain low levels of polyols, organic acids and carbohydrates. Amino acid profiles were similar to those of C3-type plants, including glycine/serine accumulation under photorespiration-enhancing conditions. γ-Aminobutyric acid was only detected in traces.
  • Changes in the concentrations of glycine and serine, genome annotation and targeted expression analysis together suggest the presence of a classical photorespiratory glycolate pathway in E. siliculosus rather than a malate synthase pathway as in diatoms. Several metabolic and transcriptional features do not clearly fit with the hypothesis of an alanine/aspartate-based inducible C4-like metabolism in E. siliculosus. We propose a model in which the accumulation of alanine could be used to store organic carbon and nitrogen during the light period. We finally discuss a possible link between low γ-aminobutyric acid contents and the absence of glutamate decarboxylase genes in the Ectocarpus genome.

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