Callus induction and plant regeneration from anther walls in Ziziphus jujuba Mill.

An indirect plant regeneration protocol for Chinese jujube (Ziziphus jujuba Mill.) was established. The anther walls from cultivar 'Dongzao' were used as explants to initiate callus. The highest frequency (57.8%) of callus formation was recorded on 1/2 Murashige and Skoog (MS) basal medium supplemented with 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) after 50 days culture in darkness. Then callus transferred to MS basal medium containing 0.4 mg/l thidiazuron (TDZ) and 0.2 mg/l alpha-naphthalene-acetic acid (NAA) for propagating in 3 months. Subsequent subculture of callus on MS medium with different concentrations of various plant growth regulators (PGRs) induced shoot organogenesis after 50 days of culture. The best combination of PGRs was 1.0 mg/l TDZ and 0.4 mg/l NAA with the highest shoot induction response (100%) and a higher number of shoots/callus (3.9). The addition of GA(3) showed inhibitory effects in inducing shoots from callus. All the hyperhydric shoots were transferred to restoration medium. The combination of 0.2 mg/l 6-benzyladenine (BA), 0.1 mg/l indole-3-butyric acid (IBA) and 1.5 mg/l polyvinyl alcohol (PVA) promoted the highest rate of hyperhydric shoots restoration (48.9%). The addition of GA(3) showed inhibitory effects in overcoming hyperhydricity. Roots formed on 43.3% of plantlets when they were cultured on 1/2 MS medium supplemented with 1.5 mg/l indole-3-acetic acid (IAA), with a mean length of 4.2 cm after 4 weeks of culture. Of the rooted plantlets, 50% survived acclimatisation and got new growth after 4 weeks. This system of adventitious shoot production from callus could be useful for the genetic engineering in Chinese jujube.