Induction of somatic embryogenesis in saffron using thidiazuron (TDZ)

Traditional propagation method of saffron is slow and the corms can be infected by many pathogens and soil-born diseases which are easily expanded during the replanting process, affecting plant growth and development and consequently reducing flowering am] saffron production potential considerably. 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'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, 0.5 mg.L-1 was the most effective treatment for embryogenesis induction. Embryogenic calli (globular stagel proliferated well when subcultured into NIS 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.