Micropropagation of Grewia tenax (Forssk.) Fiori – an important ethnomedicinal plant

Grewia tenax (Forssk.) Fiori is a multi-purpose shrub species that is threatened in its natural environment because of extensive fruit collection and seed dormancy. We induced direct multiple shoots of G. tenax from the cotyledonary node, shoot, and stem node explants. The explants were cultured on a Murashige and Skoog (MS) solid medium supplemented with up to 4.0 mg/l of benzyladenine (BA), kinetin (Kin), isopentanyl adenine (2iP), or thidiazuron (TDZ). The highest number of shoots (4.8 ± 0.4) was obtained when 2-shoot explants regenerated on the primary medium containing 3.0 mg/l 2iP were subcultured onto a secondary medium containing 1.0 mg/l BA. The induced-microshoots were transferred to either 1/4, 1/2, or full MS medium strengths. The use of a 1/4- strength MS medium resulted in the formation of the highest number of roots and root length compared to a 1/2- and full-strength MS. To improve rooting performance, indole-3-butyric acid (IBA) in various concentrations (up to 1.0 mg/l) was provided to a 1/4-strength MS medium. The average longest root (3.2 ± 0.4 cm) was achieved on a medium supplemented with 0.2 mg/l IBA. A rooting frequency of 100% and the maximum number of roots (6 ± 1.5) per explant were obtained using 1/4-strength MS medium containing 1.0 mg/l IBA, and in vitro plantlets were successfully acclimatized with a 75% survival rate. This study provides an efficient in vitro propagation system for G. tenax.