High-frequency adventitious shoot organogenesis from stem explants of Grossh.

The present study introduced an shoot organogenesis protocol for the medicinal plant (Lamiaceae). Stem, leaf, and petiole explants were cultured in half-strength Murashige and Skoog (MS) medium containing different concentrations of 6-benzylaminopurine (BAP) alone or in combination with thidiazuron (TDZ), indole-3-butyric acid (IBA), or α-naphthalene acetic acid. Callus formation occurred from stem and petiole explants in most cultures; however, in leaf explants, it was observed only in cultures containing 0.5 mg/l BAP supplemented with TDZ at all concentrations. The highest frequency of indirect shoot induction (100 and 90%) with an average of 20.33 and 12 shoots per explant was observed in stem-derived calli cultured on half-strength MS medium containing 2.0 mg/l BAP plus 0.5 and 1.5 mg/l TDZ, respectively. The best direct shoot organogenesis (40%) was observed in stem explants cultured on half-strength MS medium containing 0.5 mg/l BAP and 0.5 mg/l IBA with a mean of 18 shoots per stem explant. The regenerated micro-shoots were elongated on a medium fortified with 0.5 mg/l gibberellic acid and then successfully rooted in half-strength MS medium supplemented with 0.5 mg/l IBA. The obtained plantlets were acclimatized in a growth chamber with a survival rate of 100%. This study is the first report of a simple and efficient shoot organogenesis and regeneration protocol for by using stem explants, which could be useful for the conservation, genetic manipulation, and exploitation of biological molecules of this valuable genetic source.