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

Abstract

This study reports the response to salinity stress (100 mM, 200 mM, and 300 mM NaCl concentration) exposure of thecommercially valuable medicinal plant Stevia rebaudiana during micropropagation for 4 weeks. The significant enhancement ofphysiological parameters, steviol glycosides (SGs), i.e. rebaudioside A and stevioside, as examined by high-performance liquidchromatography, 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 100mM NaCl stress. Callus formation produced similar results regarding physiology and antioxidant assays, except that it producedmerely a negligible amount of SGs. Contrarily, root formation showed marked susceptibility to 100 mM, 200 mM, and 300 mM NaClconcentrations and reduced growth parameters, sweetening compounds, and secondary metabolites. Hence, NaCl plays the role ofabiotic stress elicitor, causing accumulation of reactive oxygen species and thus altering metabolic processes and physiology of Steviaunder in vitro culture conditions.