Varietal Differences of Regenerative Ability in Sweet Basil (<i>Ocimum basilicum</i> L.)

To establish efficient regenerative conditions for sweet basil (Ocimum basilicum L.), we evaluated the differences in shoot formation from first true leaf explants for nine cultivars. The shoot formation rates of six of nine cultivars from the calli cultured in media with 3.7 mg L-1 of thidiazuron (TDZ) as a plant growth regulator, ranged from 6.7% to 15.0%, indicating insufficient rates for efficient regeneration. Further analyses were conducted using ‘Eleonora’, ‘Minimum’, and ‘Rubin’, which represented relatively high shoot formation rates in the first experiment. When the hypocotyls and cotyledons were cultured as explants on media supplemented with various concentrations of benzylamino purine (BA), TDZ and N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU), the highest shoot formation rates of 50.0% to 66.7% were observed in media supplemented with 3.0 mg L-1 of TDZ for ‘Elenora’, 1.0 mg L-1 of BA for ‘Minimum’, and 1.0 and 3.0 mg L-1 of TDZ for ‘Rubin’, respectively. These shoots were efficiently rooted in the media supplemented with 1.0 mg L-1 naphthalene acetic acid for ‘Minimum’, and 1.0 mg L-1 indole butyric acid for ‘Eleonora’ and ‘Rubin’. These results are expected to be valuable for mass propagation and genetic transformation of sweet basil.