Interactive effect of light, temperature and TDZ on the regeneration potential of leaf discs of Fragaria x ananassa Duch

This is the first report where shoot regeneration in strawberry cultivar Chandler has been achieved simultaneously through both somatic embryogenesis and shoot bud formation. Direct somatic embryogenesis was observed in leaf discs which were cultured on medium containing MS salts + B5 vitamins + 2% glucose + 18.16 μM thidiazuron (TDZ) and given both chilling and dark treatment for 2 wk at 4±2°C followed by incubation at 25±2°C under 16-h photoperiod for third wk. After 3 wk, these explants were then subcultured on medium containing MS salts + B5 vitamins + 2% glucose and incubated under 16-h photoperiod at 25±2°C for further growth and development. Direct regeneration via de novo shoot bud formation was observed in leaf disks which were given dark treatment and were cultured on medium containing MS salts + B5 vitamins + 2% glucose supplemented with 9.08 μM TDZ. There was a synergistic effect of photoperiod, dark, and chilling treatments on somatic embryogenesis, whereas chilling treatment had an inhibitory effect on shoot organogenesis.