Studies on the Organogenesis in Carrot Tissue Cultures II. Effects of Amino Acids and Inorganic Nitrogenous Compounds on Somatic Embryogenesis

Abstract

Listen

Translate article

The effects of nitrogenous compounds on organogenesis in Daucus carota L. cv. US-Harumakigosun cultured in vitro were examined. Reduced nitrogenous compounds like ammonium nitrate or ammonium chloride with added nitrate such as potassium nitrate were very effective in inducing somatic embryogenesis, but ammonium sulfate was not. A high level of potassium nitrate in a medium (without reduced nitrogen) slightly stimulated it. The process of somatic embryogenesis seems to consist of two sequential phases: the induction phase and the development phase. The former requires 2,4-D, but not any nitrogenous compounds, while the latter requires the reduced nitrogen. The effects of different L-amino acids on embryo formation in suspension cultures were also examined. When various amino acids were individually added to a basal medium which contained potassium nitrate (20 mM) as a principal source of nitrogen, α-alanine was the most effective at higher concentration (5 to 10 mM), and glutamine, asparagine, aspartic acid, glutamic acid, arginine and proline were also stimulatory, but lysine, valine, histidine, leucine and methionine were not effective. β-alanine did not stimulate embryo formation and pyruvic acid counteracted the stimulative effect of glutamic acid. The addition of α-alanine accelerated the cell division during the earlier stage of embryogenesis and increased the number of embryos per cell cluster. Of the various amino acids added individually to a medium without any nitrogenous compounds, glutamine stimulated somatic embryogenesis the most; and a-alanine and glutamic acid were also effective at higher concentrations (10 to 30 mM). Arginine, asparagine, aspartic acid, threonine and proline seemed to be not effective in the stimulation of embryo formation in the absence of other nitrogenous compound.