In vitro propagation of Indian Kino (Pterocarpus marsupium Roxb.) using Thidiazuron

Abstract

An efficient protocol was developed for micropropagation of an economically important timber-yielding multipurpose tree, Pterocarpus marsupium Roxb. Multiple shoots were induced from cotyledonary nodes (CNs) derived from 18-d-old axenic seedlings on Murashige and Skoog (MS) medium supplemented with thidiazuron (TDZ) (0.1–10 μM). The highest shoot regeneration frequency (90%) and maximum number (15.2 ± 0.20) of shoots per explant was recorded on MS medium amended with 0.4 μM TDZ. Continuous presence of TDZ inhibited shoot elongation. In the primary medium, TDZ-initiated cultures were transferred to the secondary medium supplemented with another cytokinin, 6-benzyladenine (BA), for shoot growth and elongation. Maximum (90%) shoot elongation with an average shoot length of 5.4 ± 0.06 cm was observed at 5 μM BA. To further enhance the number of shoots per explant, mother tissue was repeatedly subcultured on fresh shoot induction medium after each harvest of newly formed shoots. Thus, by adopting this strategy, an average of 44 shoots per explant could be obtained. About 65% of in vitro regenerated shoots produced a maximum number (4.4 ± 0.2) of roots per shoot by a two-step culture procedure employing pulse treatment and subsequent transfer of treated shoots to a low concentration of 0.2 μM indole-3-butyric acid along with phloroglucinol (3.96 μM). The in vitro-raised plantlets were successfully acclimatized first under culture room conditions, then to greenhouse with 70% survival rate.