Establishment of adventitious root suspension cultures in basil (Ocimum basilicum L.) plant and determination of the effects of some elicitors applications on rosmarinic acid production

In this study, it was aimed to determine the effects of various elicitor applications on rosmarinic acid production, biomass amount and antioxidant activity in basil (Ocimum basilicum L.) adventitious root suspension cultures. In addition, the effects of elicitors on total phenolic compound and flavonoid content were also evaluated. Hypocotyl parts of one-month-old plants grown in in vitro culture conditions were used as explant source in the establishment of adventitious root culture. Explants were cultured in 0.75 MS (Murashige and Skoog) nutrient medium containing 2 mg L-1 IBA (Indole-3-butyric acid), 30 g L-1 sucrose and 2 g L-1 phytagel in dark conditions. Adventitious roots grown in these culture conditions were cultured in Erlenmeyer flasks (250 mL) containing 100 mL of nutrient medium with the same content (without phytagel) at 120 rpm on a shaker. On the 26th day of suspension culture, yeast extract (125, 250 and 500 μg mL-1), calcium chloride (5 and 10 mM) and sodium selenite (4 and 8 mg L-1) were added to the nutrient medium as elicitors at different concentrations. Adventitious roots were harvested on the 30th day of suspension culture, their wet weights were weighed and then dried. The rosmarinic acid content of the dried adventitious root samples was analyzed by HPLC. Free radical scavenging (DPPH), cation radical scavenging (ABTS) and reducing power (FRAP) activities were determined spectrophotometrically. Among the elicitor applications, the highest increase in rosmarinic acid content was determined in adventitious roots treated with 125 μg mL-1 yeast extract. In this application, the amount of rosmarinic acid increased 1.44 times compared to the control group and became 40.44 mg g-1 DW. In terms of total phenolic and flavonoid content, the highest values were determined in the adventitious roots applied 125 μg mL-1 yeast extract. Calcium chloride and sodium selenite applications significantly increased rosmarinic acid, total phenolic and flavonoid content compared to the control group. In terms of these applications, the highest increase in rosmarinic acid content was 1.25 and 1.24-fold in adventitious roots treated with 5 mM calcium chloride and 8 mg L-1 sodium selenite, respectively. In addition, all elicitor applications significantly reduced the biomass amount of adventitious roots compared to the control. The highest DPPH, ABTS and FRAP activities were determined in adventitious roots treated separately with 125 μg mL-1 yeast extract, 5 mM calcium chloride and 8 mg L-1 sodium selenite. Also, a strong correlation was determined between antioxidant activity and metabolite amounts. As a result, it is thought that the adventitious roots obtained from basil plant are suitable materials to produce rosmarinic acid and the findings obtained from this study will make an important contribution to large-scale production.