Induction of somatic embryogenesis in saffron using thidiazuron (TDZ)

In vitro propagation of saffron either through somatic embryogenesis or cormogenesis is considered to be an efficient alternative method for large-scale propagation of pathogen-free corms. In order to develop an efficient protocol for in vitro propagation of saffron, a factorial experiment was carried out based on completely randomized design to investigate the effects of various concentrations of TDZ (0, 0.1, 0.25 and 0.5 mg L(-1)) on somatic embryogenesis induction from 5 different types of corm explants (terminal or axillary buds, upper or lower parts of the corm tissue and terminal buds from pre-treated corms at 4 degrees C for 2 weeks). The results revealed that TDZ concentrations affected the induction of somatic embryogenesis significantly while different types of corm explants showed no significant effect on this process. Among TDZ concentrations used, 0.5 mg L(-1) was the most effective treatment for embryogenesis induction. Embryogenic calli (globular stage) proliferated well when subcultured into MS medium supplemented with 0.25 mg L(-1) TDZ before transferring to hormone-free MS medium containing 6% sucrose for maturation (scutellar or horn-shape stage). Matured embryos were transferred to half strength MS medium without growth regulators for further development, from which microcorms were produced at the basal part after 3 months.