Metabolomics and Physiological Changes Underlying Increased Tolerance to Salt Stress Induced by Applied Nitric Oxide in Fatsia japonica Seedlings

Abstract

Fatsia japonica (Thunb.) Decne. et Planch. is an important woody landscape plant, and its distribution is commonly limited by salt stress. Although the application of exogenous nitric oxide (NO) has been known to be effective in alleviating abiotic stress in plants, the underlying mechanism by which NO induces salt resistance in F. japonica remains unknown. In this study, the physiological and metabolic characteristics of F. japonica seedlings with the application of NO under salt stress conditions were investigated. We demonstrated that exogenous NO (0.1 mM sodium nitroprusside, SNP) mitigated the growth inhibition caused by 0.4% NaCl. This alleviation could be attributed to NO-induced enhancement in photosynthesis, osmotic adjustment, antioxidant enzyme activities, and a reduction in oxidative damage when exposed to salt stress. Furthermore, the metabolomic analysis revealed that salt stress significantly disrupts the growth of F. japonica by downregulating sugars, sugar alcohols, amino acids, and organic acids. However, the application of exogenous NO improves sugar metabolism, enhancing the levels of fructose, glucose, mannose, galactose, xylose, ribose, inositol, and sorbitol, as well as the metabolism of amino acids and organic acids. These findings provide new insights into the physiological and metabolic homeostasis adjustments induced by NO that promote salt stress tolerance in F. japonica, enhancing our understanding of plant resilience mechanisms.