Salt stress by NaCl alters the physiology and biochemistry of tissue culture-grownStevia rebaudiana Bertoni

This study reports the response to salinity stress (100 mM, 200 mM, and 300 mM NaCl concentration) exposure of the commercially valuable medicinal plant Stevia rebaudiana during micropropagation for 4 weeks. The significant enhancement of physiological parameters, steviol glycosides (SGs), i.e. rebaudioside A and stevioside, as examined by high-performance liquid chromatography, and nonenzymatic antioxidant activities, i.e. total phenolic content, total flavonoid content, total antioxidant capacity, total reducing power, and DPPH-free radical scavenging activity, was observed during the shoot formation process under up to 100 mM NaCl stress. Callus formation produced similar results regarding physiology and antioxidant assays, except that it produced merely a negligible amount of SGs. Contrarily, root formation showed marked susceptibility to 100 mM, 200 mM, and 300 mM NaCl concentrations and reduced growth parameters, sweetening compounds, and secondary metabolites. Hence, NaCl plays the role of abiotic stress elicitor, causing accumulation of reactive oxygen species and thus altering metabolic processes and physiology of Stevia under in vitro culture conditions.