The interplay between light, plant growth regulators and elicitors on growth and secondary metabolism in cell cultures of Fagonia indica

Manipulation in the light regimes combined with the effects of plant growth regulators (PGRs) and elicitors through plant cell culture technology is a promising strategy for enhancing the yield of medicinally important secondary metabolites. In this study, the effects of interplay between PGRs, elicitors and light regimes on cell cultures of F. indica have been investigated. The results showed that callus cultures resulted in maximum biomass formation (13.2 g/L) when incubated on solid MS (Murashige and Skoog) medium containing 1.0 mg/L BA under continuous light for 4 weeks. Among the other PGRs, compared with the auxins such as 2,4-D, and IBA, TDZ resulted in higher biomass accumulation (12.1 g/L). Elicitors (Me-J and PAA) resulted in a lower growth response, when compared with cytokinins and a higher response than auxins under all the light regimes on solid MS media. However, in liquid media, no significant increase in biomass was observed in response to the combined effects of PGRs and photoperiod regimes. Further, the highest phenolic content (TPC = 6.8 mg) and flavonoid content (TFC = 5.2 mg) were detected in the dark-grown cell cultures raised in vitro at 0.5 mg/L Me-J. The highest antioxidant activity (88%) was recorded in the dark-grown cell cultures harvested from LOG phase of the growth cycle supplemented with 0.5 mg/L Me-J. Furthermore, BA resulted in considerable flavonoids production (TFC = 4.7 mg) in the cell cultures grown under continuous light. However, overall dark treatment and elicitation with Me-J resulted in the optimal metabolic response in terms of secondary metabolites accumulation in cell suspension cultures of F. indica.