The role of light in nitrite reduction; Studies with leaf discs

The reduction of nitrite by leaf discs has been studied. In short term experiments the reduction is markedly stimulated by light, but is not affected by the absence of oxygen or carbon dioxide from the gas phase. Carbon dioxide assimilation is more sensitive than nitrite reduction to 3-(3',4'-dichloro-)-1,1-dimethyl urea (DCMU) inhibition. Uncouplers such as carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) do not inhibit nitrite reduction although dinitrophenol (DNP) has a small effect.Although nitrite stimulates oxygen evolution in the light in the absence of CO2 the stoichiometry of nitrite reduction to oxygen evolution is much less than would be predicted if nitrite is simply acting as a classical Hill reagent.