Enhanced Production of Phenylethanoids Mediated Through Synergistic Approach of Precursor Feeding and Light Regime in Cell Suspension Culture of Rhodiola imbricata (Edgew.).

Precursor feeding is a potential strategy for increasing specialized metabolite production in plant cell culture systems. In the present study, cell suspension cultures were developed and subsequently evaluated for precursor feeding investigations. Cell suspension cultures were established in Murashige and Skoog (MS) medium containing 0.5 mg/L thidiazuron (TDZ) + 1 mg/L α-naphthalene acetic acid (NAA). The growth biomass and metabolite pattern were analyzed to identify specific culture days required for prolific biomass production. The maximum cell dry weight (DW) was observed in leaf cell suspension (1.22 g/100 mL) and root cell suspension culture (1.12 g/100 mL) on day 21. Afterward, the effect of precursor concentrations (tyrosol; 0.5, 1, 2, and 3 mM) along with two light regimes, photoperiod (16L/8D h, 70 µmol/m2/s) and dark (24 h), was evaluated for cell growth and metabolite accumulation. The results revealed that leaf cell suspension treated with 3 mM tyrosol concentration detected maximum salidroside content (26.05 mg/g DW) on day 15, incubated under photoperiod (16L/8D h) condition. Similarly, under photoperiod (16L/8D h), root cell suspension treated with 3 mM tyrosol produced maximum salidroside content (26.62 mg/g DW) on day 12. Moreover, the total phenolics content increased significantly (44.21 mg/g DW) on day 12 in 3 mM tyrosol treatment under photoperiod (16L/8D h). However, precursor concentrations did not influence the total flavonoids content. The present investigation suggests that the immediate pathway precursor, tyrosol, has a strong effect on enhanced production of salidroside, irrespective of explant type and light regimes.