Development of somatic embryogenesis of mangrove fan palm (Licuala spinosa Thunb.) from culturing immature zygotic embryo

Mangrove fan palm is an endemic plant that grows well and has for a long period been related to traditional ceremonies in southern Thailand. It is an endangered plant with a slow growth and is difficult to propagate in mass production. Tissue culture technique can be used to produce a large number of plants within a short time and to preserve in vitro germplasm resulting in the plant not becoming extinct from natural habitats. Thus, the objectives of this research were to study effects of auxins and embryo preparation on somatic embryogenesis. The sterile immature zygotic embryo was cultured on MS medium with different types and concentrations of auxins. The results showed that 1 mg/l dicamba gave the best results in callus induction at 100% and callus diameter at 4.67 mm after 8 weeks of culture. For callus proliferation, callus chopped at 100 times and transferred to 0.1 mg/l dicamba containing oil palm culture medium gave the highest callus diameter at 10.33 mm after 4 weeks of culture and somatic embryos were also produced. Upon transferring somatic embryos to MS medium with 0.2 M sorbitol, a large number of various developmental stages of secondary somatic embryos were induced within 4 weeks. Therefore, the finding of this study could be highlighted that dicamba and chopping callus have an important role to induce callus and somatic embryo. This is the first report achieved on in vitro propagation of this plant and it will be beneficial for genetic conservation and biotechnological applications in the future.