Ultrastructure of somatic embryo development and plant propagation for Lachenalia montana

Embryogenesis for plant propagation by cell suspension culture was achieved for the first time using friable embryogenic callus (FEC) from leaf explants of Lachenalia montana Schltr. ex W.F. Barker. FEC was established with solid (8 g L− 1 agar) MS (Murashige and Skoog, 1962) medium containing various concentrations and combinations of sucrose and plant growth regulators (PGRs). The somatic embryos (SEs) were developed from FEC in liquid MS (MSL) medium with or without PGRs. A higher number of SEs of different developmental stages (26.0-19.4, globular to cotyledonary-stages respectively) were obtained on MSL medium with 0.5 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 μM thidiazuron (TDZ). The germination frequency (33.7%) was highest in MSL medium containing 1 μM 2,4-D and 2 μM TDZ. The different stages of SEs germinated (92%) on solid full-strength MS medium containing 15 g L− 1 sucrose and 10 μM phloroglucinol (PG). The plantlets were successfully acclimatized in the greenhouse. Developmental stages and features of embryoids were confirmed by histological and ultrastructural studies using light and transmission electron microscopy (TEM). Many mitochondria, lipid bodies together with starch grains, chloroplasts, Golgi apparatuses, vacuoles and nuclei were detected. The system developed offers controlled large-scale clonal propagation which ensures germplasm conservation, confirms viability of embryogenesis by ultrastructural studies and provides a system for genetic transformation studies for horticultural and ornamental improvement.