title: Metabolic and physiological adjustment of Suaeda maritima to combined salinity and hypoxia.
abstract: Suaeda maritima is a halophyte commonly found on coastal wetlands in the intertidal zone. Due to its habitat S. maritima has evolved tolerance to high salt concentrations and hypoxic conditions in the soil caused by periodic flooding. In the present work, the adaptive mechanisms of S. maritima to salinity combined with hypoxia were investigated on a physiological and metabolic level.
  
  
  
  To compare the adaptive mechanisms to deficient, optimal and stressful salt concentrations, S. maritima plants were grown in a hydroponic culture under low, medium and high salt concentrations. Additionally, hypoxic conditions were applied to investigate the impact of hypoxia combined with different salt concentrations. A non-targeted metabolic approach was used to clarify the biochemical pathways underlying the metabolic and physiological adaptation mechanisms of S. maritima .
  
  
  
  Roots exposed to hypoxic conditions showed an increased level of tricarboxylic acid (TCA)-cycle intermediates such as succinate, malate and citrate. During hypoxia, the concentration of free amino acids increased in shoots and roots. Osmoprotectants such as proline and glycine betaine increased in concentrations as the external salinity was increased under hypoxic conditions.
  
  
  
  The combination of high salinity and hypoxia caused an ionic imbalance and an increase of metabolites associated with osmotic stress and photorespiration, indicating a severe physiological and metabolic response under these conditions. Disturbed proline degradation in the roots induced an enhanced proline accumulation under hypoxia. The enhanced alanine fermentation combined with a partial flux of the TCA cycle might contribute to the tolerance of S. maritima to hypoxic conditions.
authors.forename: Jan H
authors.initials: JH
authors.lastname: Behr
authors.affiliation: UMR1349 INRA, Agrocampus Ouest, Université de Rennes 1, 35653, Le Rheu, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Bouchereau
authors.affiliation: UMR1349 INRA, Agrocampus Ouest, Université de Rennes 1, 35653, Le Rheu, France.
authors.forename: Solenne
authors.initials: S
authors.lastname: Berardocco
authors.affiliation: Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Wakehurst Place, Ardingly, West Sussex RH17 6TN, UK.
authors.forename: Charlotte E
authors.initials: CE
authors.lastname: Seal
authors.affiliation: School of Life Sciences, University of Sussex, Falmer, Brighton BN7 1BD, UK.|School of Plant Biology (M084), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Flowers
authors.affiliation: University of Hohenheim, Institute of Crop Science, Quality of Plant Products, Emil-Wolff-Str. 25, 70599 Stuttgart, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Zörb
mesh_terms: D000222:Adaptation, Physiological; D000693:Anaerobiosis; D019663:Chenopodiaceae / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D054712:Salinity; D055051:Salt-Tolerant Plants / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D012965:Sodium Chloride
keywords: Suaeda maritima; halophyte; hypoxia; metabolomics; osmotic adjustment; salinity