Initiation of callus and somatic embryos from explants of mature cotton (Gossypium klotzschianum Anderss)

Stem and petiole sections from a diploid species of cotton (Gossypium klotzschianum Anderss.) were longitudinally sliced and placed on a callus induction medium. Explants with the cut surface in contact with the medium either browned or produced a slow growing red callus which could not be subcultured. Explants oriented with the epidermis in contact with the medium produced a rapidly growing, friable, green callus which could be subcultured biweekly and has been maintained for 12 months. Globular and torpedo embryos were obtained 2 weeks after transfer of the callus to a liquid medium containing the auxin, 2,4-dichlorophenoxyacetic acid. Following subculture to an auxin-free medium, the embryos underwent additional development but plantlets were not obtained. Attempts to consistently regenerate plants from embryos are currently under way.