Integrative Physiological and Multi-Omics Insights: Salt Stress Adaptation and Functional Specialization in Suaeda...

Soil salinization, a major abiotic stress, severely limits plant growth and reduces crop yields. Understanding the salt tolerance mechanisms of halophytes is essential for the effective utilization of saline soils and improving crop resilience. Suaeda salsa L., a saline-alkali pioneer species with significant ecological and economic value, was investigated using physiological, metabolomic, and transcriptomic approaches under low, medium, and high soil electrical conductivities to elucidate its salt adaptation mechanisms. Physiological assays demonstrated that the responses were predominantly leaf-centered, with measurements of antioxidant enzymes, oxidative stress indicators, and osmolytes indicating that leaves play a key role in salt stress responses. Transcriptomic analysis revealed that the metabolic pathways were the most enriched across all conductivity comparisons. Metabolomic profiling showed that differential metabolites in the roots and leaves were enriched in starch and sucrose metabolism, whereas phenylpropanoid biosynthesis exhibited contrasting enrichment patterns in the roots and leaves under low- and high conductivity conditions. Based on these pathways, tissue-specific regulatory networks were constructed, revealing coordinated carbon allocation and the establishment of an efficient salt-tolerance network. Most genes exhibited divergent expression patterns between roots and leaves as conductivity increased, reflecting functional specialization. This study proposed that S. salsa uses a metabolic regulatory network characterized by gradient responses, functional differentiation, and energy optimization, providing a theoretical foundation for enhancing halophyte adaptation and improving crop salt tolerance.