One of the biotechnological methods considered today to increase the drug content in medicinal herbs is hairy roots induction by Agrobacterium rhizogenes-mediated transformation (ArMT). The study aimed at inducing hyoscyamine and scopolamine production in the callus and hairy roots of henbane (Hyoscyamus niger). To do this, seeds of wild H. niger growing in Hamadan province of Iran were collected and used for the experiments. A. rhizogenes strains were employed for hairy root induction. Furthermore, different concentrations of plant hormones auxin (NAA) and cytokinin (BAP) were applied for callus induction. ArMT of H. niger was confirmed by PCR amplification of rolB gene (780 bp) sequences. Upon results, induction of hairy root in H. niger was observed only when A. rhizogenes strains AR15834, A4 and D7 strains were used. Indeed, the highest percentage (63.33%) of hairy root induction was achieved by A. rhizogenes strain AR15834 applied to the leaf explants. However, root explants did not yield any hairy root and callus. Furthermore, the highest percentage (%100) of callus induction from H. niger leaf explants was observed in the solid MS medium containing 2 mg/L NAA; 2 mg/l NAA with 0.5 mg/l BAP; 2 mg/l NAA with 1 mg/l BAP; and 2 mg/l NAA with 2 mg/l BAP. Moreover, hyoscyamine and scopolamine contents were investigated by HPLC. Data indicated that dominant alkaloid both in hairy root and callus was hyoscyamine. Thus, hairy root induction by ArMT is being introduced for engineering H. niger, as a means for drug production enhancement.
