The influence of different strains of Agrobacterium on hairy root induction and the content of total phenolics and polysaccharides in medicinal plant Echinacea purpurea (L.) moench

The hairy roots induced by Agrobacterium rhizogenes due to the stability and mass production in hormone free culture provide an appropriate tissue for secondary metabolite production, and the content of metabolites produced could be affected by bacterial strain. In the current study, the effect of different strains of A. rhizogenes including A4, A13 and 15834 on the percentage of hairy root induction of Echinacea purpurea (L.) moench. in the leaf and hypocotyl explants were studied. In another experiment, total phenolics and polysaccharides content of hairy roots were measured compared to the control (untransformed) roots. The results showed that the percentage of hairy root induction was significantly affected by bacterial strains, so that in E. purpurea leaves incubated by strains A13, 15834 and A4, the hairy root induction was 60%, 40% and 0, and in hypocotyl explants was 85%, 45% and 70%, respectively. Maximum total phenolic compounds were observed in A4 strain. As well, in comparison to control, the polysaccharide content in hairy root induced by strains 15834 and A13 increased and by A4 strain decreased significantly. Differences observed in this study about hairy root induction and secondary metabolites production could be due to different ability of A. rhizogenes strains in T-DNA transferring to plant cells.