Soybean somatic embryogenesis: interactions between sucrose and auxin

The interaction between sucrose and auxin in soybean (Glycine max L. Merr.) somatic embryogenesis was investigated by culturing immature cotyledon explants on factorial combinations of NAA (6.25, 12.5, 25 and 50 mg/l) and sucrose (0.5, 1, 2 and 4%). A significant interaction between sugar and auxin was observed; balanced concentrations of the two components were required for optimal embryo production and normality. The highest numbers of normal somatic embryos were produced on media which contained combinations of low to intermediate levels of sucrose (1 or 2%) and NAA (6.25 or 12.5 mg/l). Cotyledon explants from induction media having a low (0.5%) sucrose content showed the most efficient embryogenesis in secondary culture. The highest frequencies of germination (32 to 41%) were seen among embryos induced on media containing 0.5% sucrose.