Hairy root induction and plant regeneration of medicinal plant Dracocephalum kotschyi.

Abstract

An efficient hairy root induction system for an important endangered medicinal plant, Dracocephalum kotschyi, was developed through Agrobacterium rhizogenes-mediated transformation by modifying the co-cultivation medium using five bacterial strains, A4, ATCC15834, LBA9402, MSU440, and A13 (MAFF-02-10266). A drastic increase in transformation frequency was observed when a Murashige and Skoog medium lacking NH4NO3 KH2PO4, KNO3 and CaCl2 was used, resulting in hairy root induction frequencies of 52.3%, 69.6%, 48.6%, 89.0%, and 80.0% by A4, A13, LBA9402, MSU440, and ATCC15834 strains, respectively. For shoot induction, hairy roots and unorganized tumors induced by strain ATCC15834 were placed on an MS media supplemented with 0.1, 0.25, 0.5, and 1mg/l BA plus 0.1mg/l NAA. The high frequency of shoot regeneration and number of shoot were obtained in the medium containing 0.25mg/l BA and 0.1mg/l NAA. Root induction occurred from the base of regenerated shoots on the MS medium supplemented with 0.5mg/l IBA after 10 days.