Total Phenolics And Flavonoids Content, And Free Radical Scavenging Potential Of Tissue Culture Raised Stevia Rebaudiana Bertoni

In vitro propagated plants of Stevia rebaudiana Bertoni, a natural sweetener, were evaluated for phenolic compounds and free radical scavenging potential and compared with a mother plant to test the reliability of in vitro regeneration protocol. Plants were propagated in vitro from nodal segments containing axillary buds. Explants were inoculated on Murashige and Skoog's (MS) medium containing 3% (w/v) sucrose, 0.8% (w/v) agar supplemented with 1.0µM thidiazuron (TDZ) for shoot initiation and multiple shoot formation and further transferred in half strength MS medium without any growth regulator for rooting following Lata et al. 2013 [1]. Fully rooted plantlets were successfully established in soil and grown to maturity at the survival rate of 95% in the climatic controlled indoor growing facility. Leaf samples from mother and tissue cultured raised plants were harvested at the peak vegetative stage i.e. just before flowering. Air dried and powdered leaf samples were used for further analysis. Our results show that in vitro propagated plants (IVPP) were found to be highly comparable to each other and to that of mother plant (MP) in terms of mean phenolics (IVPP: 107.70 ± 3.95 mg GAE/g dry wt., MP: 108.18 ± 1.59 mg GAE/g dry wt.), flavonoids (IVPP: 50.80 ± 2.81 mg QE/g dry wt., MP: 53.36 ± 0.46 mg QE/g dry wt.) and antioxidant properties using 2,2-diphenyl-1-picrylhydrazyl (DDPH) and cellular antioxidant (CAA) assays. These results thereby confirm the clonal fidelity of tissue culture raised S. rebaudiana plants.

Acknowledgement: This research was partially funded by a grant from the USDA, Agricultural Research Service Specific Cooperative Agreement No. 58 – 6408 – 1-603 – 07. Katherine Martin is acknowledged for biological assays.

References: [1] Hemant Lata, Suman Chandra et al. (2013) American Journal of Plant Sciences, 4: 117 – 128.