Somatic embryogenesis induction of litchi (Litchi chinensis Sonn.) from leaves of mature trees

Abstract

Induction and development somatic embryos of litchi (Litchi chinensis Sonn.) from leaflet explants obtained from mature litchi trees were investigated. Somatic embryogenesis was significantly influenced by the cultivar, plant growth regulators, position of leaflet and orientation of leaf explants. Adaxial-face up orientation of leaf explants significantly enhanced embryogenesis in comparison with adaxial-face down orientation. Maximum number of somatic embryos were obtained using median position from basal leaflet with adaxial-face up orientation cultured on Murashige and Skoog (MS) medium supplemented with 1.0 mg/l 2, 4 dichlorophenoxyacetic acid (2,4-D) and 0.5 mg/l 6-benzylaminopurine (BA) (37.67). Two types of salts media (MS and Gamborg’s B5) as well as different sucrose concentrations were examined for development and maturation of somatic embryos. MS salts medium with 45g/l sucrose was effective on size of mature somatic embryos (8.00 > 0.5 cm SE and 6.33 < 0.5 cm SE) compared with B5 salts medium (4.33 > 0.5 cm SE and 4.66 < 0.5 cm SE) on the same concentration of sucrose. Development of somatic embryos occurred on the media without growth regulators, heart and torpedo stage somatic embryos were obtained. Somatic embryos enlarged more and turned to milky opaque in color and finally reached to mature milky cotyledonary stage. Scanning electron microscopy revealed different morphological development of somatic embryos. In addition, Anatomical observation showed differences in the embryogenic and non-embryogenic cells. Furthermore, anatomical observation for development stages of somatic embryos.