Influence of KNO3, CaCl2 and MgSO4 Concentrations on Growth and Cichoric Acid Accumulation in Hairy Root Culture of Purple Coneflower (Echinacea purpurea L.)

Purple coneflower (Echinacea purpurea L.) is one of the most important medicinal plants. Hairy root culture of Echinace, represent a valuable alternative to field cultivation for the production of bioactive secondary metabolites. The present study investigates the effects of KNO3, CaCl2 and MgSO4 concentrations on growth and the biosynthesis of cichoric acid in Echinacea purpurea hairy root culture. Agrobacterium rhizogenes strain R15834 was used for hairy root induction. The experiment was performed with 0.5 g of fresh hairy roots (about 2 cm long segments) per 100 ml Erlenmeyer flasks containing 30 ml of hormone-free liquid 1/2MS salts with B5 vitamins supplemented with different amounts of KNO3 (3131, 3939, and 4747 mg/l), CaCl2 (85, 170, and 340 mg/l) and MgSO4 (370 (control), 600, and 1600 mg/l). After 4 weeks, growth parameters and cichoric acid amounts were assessed. Results indicated that the highest fresh (99.69 g/l) and dry weight (6.91 g/l) of hairy roots were achieved using 3131 mg/l KNO3. Fresh and dry weights of hairy roots in various CaCl2 and MgSO4 concentrations were not significantly different from those of control. The highest amount of cichoric acid (30.55 mg/g DW) was produced by 1600 mg/l MgSO4 treated hairy roots after 4 weeks. The present work demonstrated the effectiveness of modified 1/2MS salts supplemented with B5 vitamins medium for improving hairy root growth and in vitro production of cichoric acid.