A Comparative Analysis of the Hairy Root Induction Methods in Hypericum perforatum

Hypericum perforatum is a medicinal plant which Hypericin, Hyperforin and phenolic compounds are its active secondary metabolites. Hairy root induction by Agrobacterium rhizogenes in this plant is difficult and has low efficiency. In the present study two inoculation methods, immersion in bacterial suspension and direct injection of A. rhizogenes has been compared. For this purpose, the best conditions for H. perforatum hairy root induction including A. rhizogenes strains (A4, LBA9402, NCPPB2656), plant explants (Stem, Apical bud, leaves), co-cultivation media (MS, ½MS, B5, and ½B5) and Acetosyringone (AS) concentration (0 and 100 µM) were specified and used for comparative analysis. It was found that strain A4, Stem explants, ½MS co-cultivation medium without AS constitute the best conditions for hairy root induction of H. perforatum. Transgenic nature of the potential hairy roots was confirmed using PCR and specific rolB and rolC genes primers. The results showed that the efficiency of applying direct injection method is four times higher than immersion in bacterial suspension in H. perforatum hairy root induction. In general, the results indicate that direct injection can be the method of choice to successful hairy root induction in H. perforatum.