Abstract
Leaf segments of Rosa hybrida cv. Carl Red and R. canina were cultured on Murashige and Skoog medium (1962) (MS) containing various kinds and concentrations of auxins. In Carl Red, pale yellow calli with embryogenic potential were predominantly induced on media containing a-naphthaleneacetic acid (NAA) at a wide range of concentration (0.25-5 mg/l), whereas low concentration (0.05 mg/l ) of thidiazuron (TDZ) inhibited embryogenic calli (EC) formation. Abnormal somatic embryos were produced from EC on MS without plant growth regulator (PGR) or with 100 ml /l coconut water (CW) and shoot formation was initiated from abnormal embryos on media with 6-benzylaminopurine (BA) or TDZ in Carl Red. The regenerated shoots of Carl Red were rooted on PGR-free MS medium and successfully transplanted on the soil. In R. canina. abnormal somatic embryos were initially induced at low frequencies on media containing high concentration of NAA (5 mg/l) or 2, 4-dichlorophenoxyacetic acid (2, 4-D) (10 mg/l ). EC with abnormal embryos was further induced after the explants were transferred onto PGR-free MS medium. Green friable calli were also initiated from EC on MS with CW and differentiated to nodular structure which further initiated leaf primordia on MS with 2 mg/l BA or 0.1 mg/l TDZ. Shoot regeneration was induced from leaf primordia and abnormal embryos on MS with 2 mg/l BA or 0.1 mg/l TDZ at 6 g/l gellan gum. Normal somatic embryos with germinability were also initiated secondarily from abnormal embryos on MS with 0.1 mg/l TDZ at 6 g/l gellan gum.
