INDUCTION OF NITRATE REDUCTASE IN LEAVES OF BARLEY IN THE DARK

The induction of nitrate reductase activity in barley leaves normally requires light in addition to nitrate. However, nitrate reductase activity was induced in darkness in detached etiolated leaves when these were incubated with nitrate and glycollate. Other effective carbon compounds were sucrose, glucose or phosphoglyceric acid. Acetate, pyruvate or succinate was ineffective. Sodium bisulphite inhibited the stimulatory effect of glycollate or sucrose on enzyme induction. It is suggested that the induction of nitrate reductase requires the concomitant reduction of nitrate and that the NADH required for the reduction is derived from the metabolism of glycollate.