Long-Term Maintenance of Callus Cultures from Immature Embryo of Sorghum bicolor

2 Abstract: A protocol was developed for long-term maintenance of callus cultures, induced from immature embryo of Sorghum bicolor (L.) Moench. Maintenance of callus cultures for prolonged duration in a regenerable state is one of the most important requirements for using in vitro techniques for plant improvements. In the present study calli were maintained satisfactorily on MS medium over 57 weeks and plantlets regenerated from them on transfer to light. Immature embryo was used as source material for callus initiation. The callus cultures were cultured on MS media with 1.5 mg/L of 2,4-D (2,4-dichlorophenoxy acetic acid), 10mg/L silver nitrate (AgNo ), 400mg/L casein hydrolysate (CH), 200mg/L L-proline and L-asparagine. 3 After callus initiation cultures were maintained in dark conditions and subcultured for every 3 week intervals. Greening of callus and regeneration of shoot-buds from callus occurred on transfer to MS media with 2mg/L BAP + TDZ (Thidiazuron). These shoots grew further in media with both, BAP and TDZ, Rooting of shoots occurred on media with NAA, the rooted plantlets could be transferred to autoclaved soil. Genetically uniform plantlets regenerated continuously from established callus upto 57 weeks old; thereby helping in multiplication and to facilitate the year round availability of explants and/or somatic embryos for Sorghum tissue culture and transformation.