Mahsa Montazeri - Department of Plant Breeding and Biotechnology, Faculty of Crop Sciences, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
Ali Pakdin-Parizi - Genetics and Agricultural biotechnology Institute of Tabarestan, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran
Hamid Najafi-Zarrini - Department of Plant Breeding and Biotechnology, Faculty of Crop Sciences, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
Mohammad Azadbakht - Department of Pharmacognosy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.
Ghorbanali Nematzadeh - Department of Plant Breeding and Biotechnology, Faculty of Crop Sciences, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.
Zahra Gholami - Department of Plant Breeding and Biotechnology, Faculty of Crop Sciences, Sari Agricultural Sciences and Natural Resources University, Sari, Iran.

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 (A۴, LBA۹۴۰۲, NCPPB۲۶۵۶), plant explants (Stem, Apical bud, leaves), co-cultivation media (MS, ½MS, B۵, and ½B۵) and Acetosyringone (AS) concentration (۰ and ۱۰۰ µM) were specified and used for comparative analysis. It was found that strain A۴, 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.

Agrobacterium rhizogenes, frequency of Transformation, Induction method, Hairy root