Primary and repetitive secondary somatic embryogenesis in Rosa hybrida 'Samantha'

This study describes a plant regeneration system for Rosa hybrida 'Samantha', a mainstream commercial cultivar, via direct somatic embryogenesis. Somatic embryogenesis was induced from in vitro-derived leaf explants, achieving a frequency of 7.5% following 8 weeks of culture on a Murashige and Skoog (MS) medium supplemented with 3.0 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) and 30 g/L glucose. We evaluated the effects of various types and concentrations of carbohydrates and plant growth regulators (PGRs) on the proliferation and germination of secondary somatic embryos. MS medium containing 1.0 mg/L 2,4-D, 0.05 mg/L 6-benzyladenine (BA) and 60 g/L glucose was found to be the most effective in promoting the proliferation of somatic embryos. The highest germination rate (56.2%) of somatic embryos was observed on MS medium containing 1.0 mg/L Thidiazuron (TDZ) and 0.5 mg/L BA. Whole plantlets were obtained by culturing germinated shoots on rooting medium comprising 1/2-strength MS salts supplemented with 0.05 mg/L alpha-Naphthalene acetic acid (NAA). Plantlets grew vigorously with normal vegetative and flowering characteristics.