Plant regeneration from callus cultures of several soybean genotypes via embryogenesis and organogenesis.

Using callus derived from immature embryos, regeneration of viable plants was obtained in soybean (Glycine max (L.) Merr.). Depending on the composition of the medium, regeneration occurred via embryogenesis or via organogenesis. Embryogenesis resulted when embryos were plated on Murashige and Skoog (MS) medium containing 43 μM α-naphthaleneacetic acid. In work with the cultivar Williams 82, the addition of 5.0 μM thiamine HCl increased embryogenesis from 33% to 58% of the embryos plated. Addition of 30 μM nicotinic acid to the MS medium enhanced embryogenesis further to 76%. Organogenesis was obtained when medium containing 13.3 μM 6-benzylaminopurine, 0.2 μM and α-naphthaleneacetic acid and four times the normal concentration of MS minor salts was used. Histological studies of these cultures confirmed the organogenic and embryogenic nature of the cultures, by demonstrating the formation of shoot buds and somatic embryos, respectively. Similar responses were obtained in all 54 genotypes tested in this manner. The cultures retained the ability to regenerate complete plants for at least 12 months and 12-15 subcultures. Seeds have been obtained from several regenerated plants and when grown in the field these produced normal-appearing fertile plants.