Improving biomass and chicoric acid content in hairy roots of Echinacea purpurea L.

Echinacea purpurea L. (2n = 2x = 22), is one of the most popular medicinal plants in developed countries containing important secondary metabolites including caffeic acid derivatives, amongst which chicoric acid is the most significant. Chicoric acid has positive effects on human immune system. Hairy roots culture of E. purpurea is an efficient method for producing chicoric acid, because of their rapid growth and higher chicoric acid content compared to an intact plant. In this research, the effects of simultaneous changes in [sucrose and NH4NO3] and [sucrose and Ca(NO3)2] concentrations, as well as the effect of change in KH2PO4 concentration, were studied on the dry weight (DW) of diploid hairy roots of Echinacea purpurea in woody plant medium (WPM). Additionally, the effects of the individual and simultaneous application of phenylalanine (the precursor of phenolic compounds) and methyl jasmonate (the inducer of phenolic compounds synthesis pathway) were investigated on chicoric acid content in diploid and tetraploid Echinacea purpurea hairy roots. The highest DW of diploid hairy roots (0.525 g per 60 mL) was produced by the treatment including 500 mg L−1 NH4NO3 and 60 g L−1 sucrose. Furthermore, results revealed that the tetraploid hairy roots treated with 1 mM phenylalanine for 72 h produced the highest amount of chicoric acid (14.86 mg g−1 DW), while in diploid hairy roots the highest amount of chicoric acid (8.89 mg g−1 DW), was produced by applying 5 mM phenylalanine for 72 h.