Nitrogen Compounds as Factors of Embryogenesis in vitro

Abstract

IN previous experiments^1,2, either one of the two inorganic nitrogen compounds, potassium nitrate and ammonium nitrate, could cause the formation of embryos in tissue cultures from Daucus carota. This was most clearly demonstrated with a medium (M_w) containing White's nutrient³, 2 per cent sucrose and 5 × 10⁻⁸ g/ml. of 2,4-dichlorophenoxyacetic acid (2,4-D). M_w could be converted from a “non-inductive” to an “inductive” form by the addition of either 4.16 g/l. of potassium nitrate or 1.65 g/l. of ammonium nitrate. The same effect, that is embryo formation, in the presence of a certain concentration of one of these compounds, was also obtained if a second medium (M_S) was used which differed from M_w only in the composition of the major and minor elements. Instead of White's salts and trace elements, M_S contained those of the formula developed by Murashige and Skoog⁴. One of the problems left by these results is: why do the two different nitrogen compounds have a positive effect on embryogenesis in vitro ?