Ferricyanide reductase of rose plasma membranes is regulated by nitrogen supply.

The ability of suspension-cultured rose (Rosa damascena Mill. cv Gloire de Guilan) cells to reduce ferricyanide is decreased by 50% during an overnight incubation in a low-nutrient (1 mM CaCl2, 0.1 mM KCl) solution. This loss is not observed when nitrate and/or glutamate is added to the low-nutrient medium, but it occurs in medium containing all the components needed for normal growth except nitrate plus glutamate. Thus, the cells possess both constitutive and inducible enzymes for the reduction of ferricyanide, and nitrate or glutamate is both necessary and sufficient to stimulate the production of the inducible enzyme.