Biochemical and Metabolomic Insights into the Effects of Salinity on the Endemic Halophyte Limonium irtaense from Eastern Spain

Limonium irtaense is an endemic halophyte from eastern Spain, that naturally grows under saline conditions. However, its physiological and biochemical mechanisms of salt tolerance remain unexplored, despite their potential relevance for understanding adaptive strategies in narrowly distributed coastal species. The present study investigated the effect of increasing concentrations of NaCl (0, 0.05, 0.1, 0.2, 0.3 M) on growth, biochemical traits, ion composition, and metabolic patterns of L. irtaense plants. Flowering and biomass partitioning were maintained under stress treatments. Biochemical adjustments included osmolytes and flavonoid accumulation and ion regulation. Metabolomic profiling revealed a salinity-induced reprogramming of metabolism, with key metabolites such as proline, dopamine, and sugar alcohols showing strong positive correlations with increasing salt levels. Dose-dependent metabolic adjustments were reflected in the enrichment of pathways related to amino acid biosynthesis, carbohydrate metabolism, and antioxidant responses. These findings highlight the physiological resilience of L. irtaense to moderate salinity and identify biochemical markers that not only inform conservation strategies for this endangered endemic species, but also contribute to a broader understanding of halophyte adaptation to increasingly variable environmental conditions.