Influence of the In Vitro Culture System on the Preferential Accumulation of Bioactive Compounds in Stevia rebaudiana Shoots.

The shoots of the Stevia rebaudiana plant have been identified as a significant source of biologically active compounds. Of these, phenolic compounds and steviol glycosides are of particular significance. The present study explores the effect of diverse in vitro culture systems (i.e., agar-gelled medium, static liquid medium, liquid medium with orbital agitation, and liquid medium with glass beads) on the accumulation of these compounds in stevia shoots. The results demonstrated that the presence of agitated liquid media led to a substantial augmentation in the accumulation of total soluble phenolic compounds (2.4-fold), total soluble hydroxycinnamic acids (1.9-fold), and total soluble flavonoids (1.6-fold) in comparison to shoots cultivated on agar-gelled media (control). The antioxidant capacity determined on shoots exhibited a comparable trend, with increases of 1.9-fold (DPPH assay) and 2.2-fold (FRAP assay) relative to the control. However, the highest accumulation of steviol glycosides was observed in the glass bead system, with increases of 1.4-fold compared to the control and more than 8-fold relative to liquid culture systems. These findings suggest that the biosynthetic pathways leading to phenolics and steviol glycosides are differentially sensitive to the culture system employed, thereby enabling the selection of the stevia shoot cultivation system based on the targeted metabolites.