Unravelling the metabolic signatures and associated pathways underlying saline‐alkali stress resilience in the halophyte Salvadora persica

Soil salinization and alkalization are the foremost abiotic stresses adversely affecting plant growth and yield worldwide. Salvadora persica is an important facultative halophyte that has been reported for its high salinity tolerance ability. The present study undertakes the growth, photosynthetic efficiency, chlorophyll fluorescence, antioxidative defense, ionomic adjustments, and metabolomic responses of S. persica to understand its resilience mechanisms under saline-alkali stress. Our findings reveal that S. persica undergoes substantial physiological, ionomic, and metabolic modulations for endurance under saline-alkali stress. Under saline-alkali stress, metabolomic analysis identified 75 differentially accumulated metabolites (DAMS), including amino acids, sugars, sugar alcohols, organic acids, polyphenols, and phytohormones. Notable upregulated metabolites included quercetin (+4-fold), naringenin (+2.6-fold), glycerol (+2.4-fold), and proline (+1.7-fold), whereas D-mannitol (-3.8-fold), D-talose (-2.9-fold), and GA3 (-2.8-fold) were significantly downregulated. Pathway enrichment analysis revealed alterations in key metabolic pathways, such as amino acid metabolism, starch and sucrose metabolism, tricarboxylic acid cycle (TCA cycle), glycolysis/gluconeogenesis, and photosynthetic carbon fixation. A 2-fold reduction in glucose indicated an enhanced glycolytic flux to support energy needs under stress. The study highlights S. persica's adaptive strategy of slower nitrogen metabolism, increased glycolysis, and downregulated TCA cycle, giving an indication towards a slower growth rate under saline-alkali stress to reallocate energy for osmolyte biosynthesis. The amino acids, sugars, and sugar alcohols emerged as major contributors to osmotic adjustment. A robust antioxidant defense system exists in S. persica to mitigate ROS under saline-alkali stress. These findings provide insights into the mechanisms of saline-alkali tolerance in the halophyte S. persica, offering valuable direction for developing saline-alkali-tolerant crops.