New protocol for the indirect regeneration of the Lilium ledebourii Bioss by using bulb explants

Lilium ledebourii Bioss is a wild species of Lilium, which grows naturally in some provinces of Iran. Previous studies on Lilium tissue culture have been linked to direct regeneration and a few studies have been conducted on indirect regeneration, which has been studied under bright conditions. In this study, for the first time in the world, all the stages of indirect regeneration (callus induction, shoot and root induction) have been studied under dark conditions. Callus formation and the regeneration levels of L. Ledebourii Bioss were examined for three replicates in an MS (Murashige and Skoog) medium with different hormonal compositions and by using a factorial experiment in the framework of a completely random plan. For callus initiation, 2,4-D and kinetin hormones were used in five and four levels, respectively, as auxin and cytokinin. Results showed that the highest percentage of the callus was found in 3 μM of 2,4-D and 0.5 μM of kinetin. In terms of callus wet weight, the highest amount was found in 3 μM of 2,4-D and 0.5 μM of kinetin. In addition, in terms of diameter, the highest amount was found in 3 μM of 2,4-D, and 0.5 μM of kinetin. In summary, the 2,4-D hormone had a major impact on the percentage of regeneration increase so that the best response was related to the composition of 3 μM of 2,4-D, and 0.1 μM of kinetin. This study contended that auxin and cytokinin can induce long shoots and roots through cell elongation in dark condition.