title: Integrative analysis of metabolite and transcript abundance during the short-term response to saline and oxidative stress in the brown alga Ectocarpus siliculosus.
abstract: The model brown alga Ectocarpus siliculosus undergoes extensive transcriptomic changes in response to abiotic stress, many of them related to primary metabolism and particularly to amino acid biosynthesis and degradation. In this study we seek to improve our knowledge of the mechanisms underlying the stress tolerance of this alga, in particular with regard to compatible osmolytes, by examining the effects of these changes on metabolite concentrations. We performed extensive metabolic profiling (urea, amino acids, sugars, polyols, organic acids, fatty acids) of Ectocarpus samples subjected to short-term hyposaline, hypersaline and oxidative stress, and integrated the results with previously published transcriptomic data. The most pronounced changes in metabolite concentrations occurred under hypersaline stress: both mannitol and proline were accumulated, but their low final concentrations indicate that, in this stress condition, both compounds are not likely to significantly contribute to osmoregulation at the level of the entire cell. Urea and trehalose were not detected in any of our samples. We also observed a shift in fatty acid composition from n-3 to n-6 fatty acids under high salinities, and demonstrated the salt stress-induced accumulation of small amounts of γ-aminobutyric acid (GABA). GABA could be synthesized in E. siliculosus through a salt stress-induced putrescine-degradation pathway.
authors.affiliation: UPMC Univ Paris 6, UMR 7139 Marine Plants and Biomolecules, Station Biologique, F-29680, Roscoff, France.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Dittami
authors.forename: Antoine
authors.initials: A
authors.lastname: Gravot
authors.forename: David
authors.initials: D
authors.lastname: Renault
authors.forename: Sophie
authors.initials: S
authors.lastname: Goulitquer
authors.forename: Anja
authors.initials: A
authors.lastname: Eggert
authors.forename: Alain
authors.initials: A
authors.lastname: Bouchereau
authors.forename: Catherine
authors.initials: C
authors.lastname: Boyen
authors.forename: Thierry
authors.initials: T
authors.lastname: Tonon
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000235:genetics*; D008353:Mannitol / Q000378:metabolism; D055442:Metabolome; D018384:Oxidative Stress / Q000235:genetics*; D000459:Phaeophyceae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000235:genetics; D014158:Transcription, Genetic; D014508:Urea / Q000378:metabolism; D014882:Water-Electrolyte Balance; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D000596:Amino Acids; D005227:Fatty Acids; D008353:Mannitol; D012965:Sodium Chloride; D005680:gamma-Aminobutyric Acid; D014508:Urea