Plant regeneration from embryogenic cell suspension cultures of wild sorghum (Sorghum dimidiatum Stapf.)

A simple and efficient protocol is described for regeneration of wild sorghum (Sorghum dimidiatum) from cell suspension cultures. Fast-growing cell suspensions were established from shoot-meristem-derived callus. Plating of the suspension on Murashige and Skoog agar medium supplemented with 2.5 mg 1(-1) 2,4-dichlorophenoxyacetic acid (2,4-D) resulted in the formation of embryogenic calli. High-frequency (80%) somatic embryogenesis from small cell clusters (300-400 mu m) was observed when the cultures were initially maintained in liquid medium with reduced levels of 2.4-D (0.25 mg 1(-1)), followed by transfer to regeneration medium. Direct plating of these small clusters on regeneration medium or transfer to liquid regeneration medium containing kinetin and 6-benzylaminopurine resulted in the development of mature somatic embryos and plantlets. The regenerants developed to maturity and were all phenotypically and cytologically normal.