Influence of light quality on growth, secondary metabolites production and antioxidant activity in callus culture of Rhodiola imbricata Edgew.

Rhodiola imbricata is a rare medicinal herb well-known for its adaptogenic and antioxidant properties due to the presence of a diverse array of secondary metabolites, including phenylethanoids and phenylpropanoids. These secondary metabolites are generating considerable interest due to their potential applications in pharmaceutical and nutraceutical industries. The present study investigated the influence of light quality on growth, production of industrially important secondary metabolites and antioxidant activity in callus cultures of Rhodiola imbricata. Callus cultures of Rhodiola imbricata were established under different light conditions: 100% red, 100% blue, 100% green, RGB (40% red: 40% green: 20% blue) and 100% white (control). The results showed that the callus cultures grown under red light accumulated maximum amount of biomass (7.43 g/l) on day 21 of culture, as compared to other light conditions. Maximum specific growth rate (0.126 days-1) and doubling time (132.66 h) was observed in callus cultures grown under red light. Reverse phase-high performance liquid chromatographic (RP-HPLC) analysis revealed that the callus cultures exposed to blue light accumulated maximum amount of Salidroside (3.12 mg/g DW) on day 21 of culture, as compared to other light conditions. UV-Vis spectrophotometric analysis showed that the callus cultures exposed to blue light accumulated maximum amount of total phenolics (11.84 mg CHA/g DW) and total flavonoids (5.53 mg RE/g DW), as compared to other light conditions. Additionally, callus cultures grown under blue light displayed enhanced DPPH free radical scavenging activity (53.50%). Callus cultures grown under different light conditions showed no significant difference in ascorbic acid content (11.05-13.90 mg/g DW) and total antioxidant capacity (27.37-30.17 mg QE/g DW). The correlation analysis showed a positive correlation between total phenolic content and DPPH free radical scavenging activity in callus cultures (r = 0.85). Taken together, these results demonstrate the remarkable potential of light quality on biomass accumulation and production of industrially important secondary metabolites in callus cultures of Rhodiola imbricata. This study will open new avenues and perspectives towards abiotic elicitation strategies for sustainable growth and enhanced production of bioactive compounds in in-vitro cultures of Rhodiola imbricata.

[Effects of different light and GA3 on the germination and seedling growth of Rhodiola sachalinensis].

OBJECTIVE: To improve germination rate and research the seed germination character of Rhodiola sachalinensis. METHODS: Made seed germinated under water or with moisture, at light or dark condition, effects of 6 different light qualities (black, white, blue, green, red and far red light) illumination on seed germination were studied. The seedling growth at different temperature were studied as well. RESULTS: The results indicated that light was required for Rhodiola sachalinensis seeds germinate, 83.3% germination rate at light and soaking in watercondition; Seed germination were improved to 84%, 70.7% and 52.0% respectively in white, red and green light quality illumination, the germination rate reached 84% after 9 h of white light illumination. Germination rate were 80% after 100 mg/L GA3 treatment for 3 h under dark condition. 20 degrees C was the optimal temperature for Rhodiola sachalinensis seedling growth, under with the plant height, fresh weight and dry weight of plant were the best. Seedling growth rate and the dry weight increased obviously at 35 d and 50 d. CONCLUSION: The experiment definited the best condition for Rhodiola sachalinensis seed germination and seedling growth, supplied basic data for large scale planting Rhodiola sachalinensis using seed propagation technology.