title: Diurnal oscillations of metabolite abundances and gene analysis provide new insights into central metabolic processes of the brown alga Ectocarpus siliculosus.
abstract: • 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. gamma-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 -aminobutyric acid contents and the absence of glutamate decarboxylase genes in the Ectocarpus genome
authors.affiliation: UMR 118 INRA, Agrocampus Ouest, Université de Rennes 1, Amélioration des Plantes et Biotechnologies Végétales, Campus de Beaulieu, F-35042 Rennes Cedex, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Gravot
authors.forename: Simon M
authors.initials: SM
authors.lastname: Dittami
authors.forename: Sylvie
authors.initials: S
authors.lastname: Rousvoal
authors.forename: Raphael
authors.initials: R
authors.lastname: Lugan
authors.forename: Anja
authors.initials: A
authors.lastname: Eggert
authors.forename: Jonas
authors.initials: J
authors.lastname: Collén
authors.forename: Catherine
authors.initials: C
authors.lastname: Boyen
authors.forename: Alain
authors.initials: A
authors.lastname: Bouchereau
authors.forename: Thierry
authors.initials: T
authors.lastname: Tonon
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics*; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D005796:Genes / Q000235:genetics*; D008353:Mannitol / Q000378:metabolism; D055442:Metabolome / Q000235:genetics*; D055432:Metabolomics; D008954:Models, Biological; D000459:Phaeophyceae / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D008353:Mannitol; D002244:Carbon