Somatic Embryogenesis Of Muscari Armeniacum And Plant Regeneration

Plant regeneration from leaf explants of Muscari armeniacum via both direct and indirectsomatic embryogenesis was established. Physiological characteristics of organogenesis andsomatic embryogenesis were studied in this paper. The optimal plant growth regulatorconcentrations for both direct and indirect somatic embryogenesis were screened withorthogonal design test. Histological observations were performed in order to understand theprocess of somatic embryogenesis. Besides, comparison of direct and indirect somaticembryogenesis was made.The results are as follows:1. There was great difference between somatic embryogenesis and organogenesis inantioxidant enzyme activities, soluble sugar and protein contents, and the difference startedfrom the callus formative period. Therefore, the callus formative period played an importantrole on regulation of o rganogenesis and somatic embryogenesis.2. MS medium containing0.1mg/L6-BA and0.1mg/L TDZ was the best for direct somaticembryogenesis of leaf explants, since88.16%cultured explants produced embryos at anaverage29.67embryos per explants.3. The best medium for indirect somatic embryogenesis was MS medium with0.5mg/L2,4-D and0.1mg/L TDZ, since all leaf explants on the medium turned into embryogenic callus,and each piece of embryogenic callus produced embryos at an average of113.33per callus.4. It was found from histological analysis that somatic embryo of M. armeniacum originedfrom a single cell, it went through four stages: single cell proembryo, bicellular proembryo,four-cell proembryo and multicellular proembryo, and finally formed as proembryo. Somaticembryos of M. armeniacum originated from both inner and outer cells, and mainly from innercells. The development of a somatic embryo of M. armeniacum went through four stages:proembryo, globular embryo, partial pear-shaped embryo and club-shaped embryo, and thenbecome an independent plant, which is similar to the development of zygote embryo ofmonocotyledons. The bipolarity of somatic embryo was shown at partial pear-shaped stageand club-shaped stage. The club-shaped embryo showed initiation of vascularisation, since aprocambium with tracheid was observed in the middle of the embryo. An isolation layer ofsomatic embryo was found at all stages, which could keep embryos apart from cells around. 5. Compared with indirect somatic embryogenesis, it takes less time for plant regenerationvia direct somatic embryogenesis, and less abnormal embryos were achieved through directway. Therefore, direct somatic embryos were more suitable for plant propagation and genetictransformation.