Hairy roots culture is a potential system for secondary metabolite production in medicinal plants. In this research, hairy root induction in Echinacea angustifolia was established using Agrobacterium rhizogenes. The effects of different A. rhizogenes strains (AR15834, A4, K599 and MSU440) in two solid growth regulator- free culture media, half strength MS salts with B5 vitamins and WPM, were evaluated on hairy root induction in 60-day-old explants. The highest percentage of root induction was obtained by AR15834 strain in the WPM medium (46.6%). Also, the effects of age (20, 40 and 60 day-old) and type (leaf, leaf lamina and petiole) of explant on hairy root induction were investigated by AR15834 strain in the WPM medium. The high frequency of hairy root induction was obtained in leaf explants (52.4%) and 40 day-old leaf explants (62.3%).Transgenic hairy roots were confirmed by PCR analysis with specific primers of rolB gene.
