Callus and embryoid formation from protoplasts of Helianthus annuus.

Sunflower hypocotyl protoplasts have been isolated and cultured. Optimum plating density for cell division and colony formation was in the range of 5 to 7×10(4) cells/mi in an agarose medium supplemented with BAP (1 mg/l) and NAA (1 mg/l). Plating efficiency was 60% after 21 days of culture. In the resultant culture a mixed population of calli and embryoids was observed. Thirty seven percent of the cell clusters exhibited a developmental pattern similar to an embryoid. Many stages of embryogenesis were observed in the same cultures.