Metabolism regulation during salt exposure in the halophyte Cakile maritima

The halophyte Cakile maritima is a Brassicacea that has developed numerous mechanisms for managing salt. In the present study, we analyze the metabolic responses of C. maritima to increasing salt exposure in parallel with growth and photosynthetic parameters. At 10 days, 100 mM NaCl treatment has no effect, whereas 400 mM treatment decreases both growth and photosynthetic capacity. Accordingly, the metabolism was weakly impacted at 100 mM NaCl with an increase in only a few amino acids and sugars, whereas 400 mM treated plants shows noticeable changes: an increase in amino acid abundance, sugars decrease and an organic acid depletion. At 20 days, 400 mM treatment leads to more severe effects on growth and photosynthesis, whereas plant growth remains unaffected by the 100 mM NaCl treatment, despite a reduction in photosynthetic capacity. Plants treated with 400 mM NaCl present an amplified metabolic response with additional metabolites reflecting salt stress as GABA, proline and glycine. One noticeable feature of halophily in C. maritima is the increase in sugar content at low stress whereas longer or higher stress lead to a decrease in sugar content. In high salt conditions the stimulation of amino acid biosynthesis is the main strategy for osmoprotection to cope for salt stress.