Production of flavonoids by Psoralea hairy root cultures

Eighteen transformed root cultures from 7 Psoralea plant species (Leguminosae) were established with the objective of producing daidzein and related flavonoids. All the 18 hairy root lines grew fast and had the same capacities for biomass production. Each of them produced daidzein as an intracellular secondary metabolite. The Lach5 hairy root line, obtained from P. lachnostachys, was a high producing line for daidzein and was further studied for biomass and flavonoid production. This root line showed exponential growth. Chitosan was used for elicitation purposes as well as for its permeabilizing effect. Little elicitation effect could be demonstrated and the metabolite release in the medium was weak (about 1%) and limited to the first 29 h after chitosan addition. Daidzein was demonstrated to be more concentrated in young parts (apexes) whereas coumestrol content was higher in older parts (brown tissues). Compared to callus cultures from the same plant species, hairy roots displayed comparable concentrations. However, high-producing lines were more frequently found with hairy roots (4 out of 18) than with callus cultures (4 out of 217).