Mass cloning of Rose and Mussaenda, popular garden plants, via somatic embryogenesis

Protocols were developed for propagation of Rosa hybrida cv. Landora and Mussaenda erythrophylla cv. Rosea via somatic embryogenesis by manipulating growth regulators and culture conditions. Calli were induced from young leaf explants of Rosa hybrida cv. Landora and Mussaenda erythrophylla cv. Rosea on Murashige, Skoog medium supplemented with 6-benzylaminopurine or kinetin along with indole-3-acetic acid or 2,4-dichloroacetic acid within four weeks of culture. The calli were subcultured either in the same medium or in a modified medium for induction of embryogenic callus. Embryogenic calli in rose were developed on Murashige, Skoog medium supplemented with 0.5-1.0 mg/l 6-benzylaminopurine, 2.0 mg/l 2,4-dichloroacetic acid, and 400-800 mg/l l-proline or l-glutamine. The results showed that stimulation of auxin-induced somatic embryogenesis by proline has a great impact on development of somatic embryos and secondary somatic embryogenesis in rose. In Mussaenda, embryogenic calli were developed on Murashige, Skoog medium supplemented with 0.5-1.0 mg/l 6-benzylaminopurine, 2.0-3.0 mg/l indole-3-acetic acid, and 10 mg/l ascorbic acid. Somatic embryos were isolated and transferred to half-strength Murashige, Skoog medium supplemented with 0.25-0.5 mg/l 6-benzylaminopurine + 0.1 mg/l gibberelic acid + 5.0 mg/l adenine sulfate and 2% sucrose for maturation and germination. About 70% somatic embryos of Mussaenda germinated. The rose somatic embryos, however, did not germinate. The somatic embryos of rose, when incubated in the dark at 4°C for two weeks and transferred to 1/2 strength Murashige, Skoog medium supplemented with 0.5 mg/l 6-benzylaminopurine, 0.25 mg/l gibberelic acid, and 2% sucrose, showed 60% germination. The seedlings showed a distinct shoot development but the radicles were blunt without well-defined root system. The shoots were harvested and cultured in the multiplication medium containing Murashige, Skoog medium supplemented with 1.0 mg/l 6-benzylaminopurine and 0.1 mg/l indole-3-acetic acid for four weeks and then subcultured in the same medium for further multiplication. The somatic embryos of Mussaenda erythrophylla cv. Rosea germinated into normal plantlets with distinct shoot and well-developed root system. The somatic embryo-derived plantlets grew normally and flowered within two months of transfer to the field.