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In this experiment in in vitro conserved embryogenic calli of 15 cultivars in longan were used as the materials for the studies on the induction, maturation and regeneration of somatic embryos. The results showed that the somatic embryogenesis was different among these 15 cultivars. During the induction of somatic embryo-genesis, sucrose concentrations, organic substances supplied, plant growth regulators and light quality affected the time, quantity and quality of somatic embryogenesis in different degrees. Somatic embryogenesis occurred from 15 to 35 d after induction, many of the embryoids were white in color, the frequency of somatic embryogenesis was all 100%, and the number of differentiated embryoids was from 2550-13220 per gram callus. In the stage of embryoid maturation, concentrations of sucrose, organic substances and light quality affected the size and the shape of matured embryoids, from 5 to 15 mm in size. The results showed that the maturation time, different types of somatic embryogenesis and light quality had great effects on the germination rates and growth of somatic embryos. Most of the normal matured somatic embryos germinated after transferred to germination medium for 15 d, and the germination rates were different from 55 to 93.3% among 15 cultivars.

Somatic embryogenesis system in longan can serve as a model experimental system of woody plants. Since 2000, on the basis of histological and cytological observations, determination of endogenous hormones and polyamines (PAs), the changes of isozymes and proteins by PAGE, IEF and SDS- PAGE analysis during longan somatic embryogenesis proteomics and molecular biology during longan somatic embryogenesis have been carried out by mRNA differential display, homologous cloning, fluorescence quantitative PCR, 2-DE and bio-mass spectrometry (MALDI-TOF or Q-TOF2) technique, to uncover the molecular mechanism of longan somatic embryo- genesis, and provide scientific evidence for regulating longan embryo development.