Influence of calcium and magnesium elimination on plant biomass and secondary metabolites of Stevia rebaudiana Bertoni

This study reports the increment in the secondary metabolites in Stevia rebaudiana plant after exposure to the elimination of Ca and Mg from Murashige and Skoog culture medium. The effect of nutrient stress on regenerants of S. rebaudiana is measured, which reveals significantly enhanced growth parameters, steviol glycosides (SGs) content, and nonenzymatic antioxidants; total phenolic content, total flavonoid content, total antioxidant capacity, total reducing power, and DPPH-free radical scavenging activity as compared with the control treatment. However, significantly highest amounts are obtained in a medium with only Ca deficiency. The amount of rebaudioside A (Reb A) and stevioside (ST) obtained in the case of Ca-deficient medium is 4.08 and 0.69%, respectively. It is followed by the results obtained from both Ca- and Mg-deprived medium [Reb A (3.23%) and ST (0.52%)] and the lowest values are obtained from medium lacking Mg only [Reb A (2.60%) and ST (0.40%)]. The most probable adaptation mechanism might be the production of reactive oxygen species by nutrients' stress, which results in secondary metabolites production as defensive moieties to overcome stress situation. This effective protocol needs to be refined to apply on an industrial scale in bioreactors for increasing quantities of commercially important pharmaceutical compounds.

Automated summary

This study demonstrates an increase in secondary metabolites in Stevia rebaudiana plants after the removal of Ca and Mg from the culture medium. Nutrient stress on regenerants of S. rebaudiana leads to enhanced growth parameters and the production of defensive secondary metabolites by generating reactive oxygen species.