Effects of Hormone and Explant Sources on Secondary Metabolite Production and Antioxidant Activities in in vitro Root Cultures of Rubia tinctorum L. (Madder)

In this study, it. was aimed to determine the effects of explant source and hormones on root and adventitious root induction in madder (Rubia tinctorum L.) plant and to determine the secondary metabolite content and antioxidant activities of the obtained roots. The stem. leaf, and root parts of 4:5 day old plants grown under i n vitro conditions were used as the source of explants for the establishment. of root and adventitious root culture. The explants were cultured in dark conditions in nutrient medium containing 4.4 g L-1 MS (Murashige and Skoog), 30 g L-1 sucrose, 2 g L-1 phytagel and 2 mg L-1 auxin. Among the auxin group hormones, indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA) were added to the nutrient medium. Root and adventitious roots growing in this nutrient medium were harvested on the 30th day and their root growth parameters were determined. These roots were dried and total anthraquinone, total phenolic and flavonoid contents were determined. In addition, the antioxidant capacities of the roots were determined by reducing power (FRAP), free radical scavenging (DPPH) and cation radical scavenging (ABTS) methods. The highest total anthraquinone, total phenolic and flavonoid contents were determined as 9.83 +/- 0.11 mg g(-1) , 14.45 +/- 0.29 mg GAE g(-1) and 3.85 +/- 0.03 mg KUE g(-1) in adventitious roots growing from stem explants in IAA nutrient medium, respectively. The highest. DPPH, ABTS and FRAP activities were also determined in adventitious roots growing from stem explants in IAA nutrient medium.