Formation of callus and somatic embryos from protoplasts of a commercial hybrid of maize (Zea mays L.).

Protoplasts isolated from a totipotent embryogenic cell suspension culture of Zea mays L. (cultivar 'Dekalb XL82') underwent sustained cell divisions when cultured in liquid as well as agarose media. Optimal colony formation (5%) occurred in a liquid medium containing 0.5 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D). A soft and unorganized callus was formed when the protocolonies were transferred to agar solidified suspension maintenance medium. Compact, organized and yellow to pale green folded structures and somatic embryos were formed upon subsequent transfer of this callus to a low 2,4-D medium. Clusters of somatic embryos germinated precociously but no plants were recovered.