Calcium increases the yield of somatic embryos in carrot embryogenic suspension cultures.

An upward shift in the concentration of calcium present in the medium during somatic embryogenesis increased the number of embryos produced approximately two-fold. This was observed when embryogenic suspension cells grown in 2,4-D medium with the normal calcium concentration of 10(-3) M were transferred to hormone-free medium containing 10(-2) M calcium and when embryogenic suspension cells grown in 2,4-D medium containing 10(-4) M calcium were transferred to hormone-free medium with 10(-3) M calcium. At calcium concentrations between 6·10(-3) and 10(-2) M globular stage somatic embryos were found in cultures supplemented with 2·10(-6) M of 2,4-D indicating that elevated calcium counteracts the inhibitory effect of 2,4-D on somatic embryogenesis. No qualitative changes were found in the pattern of extracellular polypeptides as a result of growth and embryogenesis in media with different calcium concentrations.