Plant regeneration via somatic embryogenesis in Schlumbergera truncata

Somatic embryogenesis was induced from phylloclade explants of Schlumbergera truncata cv. Russian Dancer. Callus developed on phylloclade explants and sub-cultured over a period of 16 months on MS medium containing mainly cytokinins was superior for the induction of somatic embryos compared to callus grown for a shorter time in the establishment medium. Sub-culture of callus grown in SH-or MS-based liquid media supplemented with 7.0 mu M kinetin and transferred onto solid MS-based medium with either 0.45 mu M 2,4-(D) or without hormones resulted in the differentiation into somatic embryos. SH-based medium proved better than MS-based medium when used as the first medium for the induction of somatic embryogenesis. However, somatic embryogenesis, contrary to adventitious shoot formation, was reduced when 2,4-(D) was included in the MS-based medium used for final transfer compared to the medium without growth regulators, indicating that a critical hormonal balance was reached. Somatic embryos developed root and shoot poles when grown on G medium. On this medium approximately 70% germination was recorded in the embryos that were differentiated earlier from the callus that was grown for a longer time in the establishment medium. This callus was grown on either SH- or MS-based medium supplemented with 7.0 mu M kinetin, and then transferred after 30 days (from SH medium) onto MS medium without hormones or after 40 days (from MS medium) onto MS medium with 0.45 mu M 2,4-(D). Furthermore, plants from somatic embryos were successfully potted in soil and showed further growth and formation of a second set of phylloclades (secondary phylloclades). Histological studies showed that somatic embryos had no detectable connection with the mother explants and that advanced stages of somatic embryos had a contained vascular system. In addition to the normal dicotyledonous embryos, anomalous embryos with multiple cotyledons and vase-like embryos were observed. Secondary embryos were also recorded in this study.