Effect of nitrite on primary photosynthetic processes in isolated chloroplasts of wheat grown under various conditions of nitrogen supply

In wheat chloroplasts, NO2- (5 mM) inhibited non-cyclic phosphorylation cou pled to the linear electron flow through both photosystems but stimulated c yclic phosphorylation with phenazine methosulfate (plus diuron) and electro n flux from an artificial electron donor through PSI and methylviologen to oxygen. During light energization of chloroplasts, NO2- increased the F-740 /F-695 ratio in the low-temperature fluorescence spectra, thus suggesting t hat the energy of absorbed quanta is redistributed in favor of PSI. Nitrite also stimulated the activity of Mg2+-dependent H+-ATPase. Changes in the s low component of the induction curve of delayed fluorescence also suggest t hat NO2- affects energy transformation processes that are coupled to electr on transport in the chloroplasts. Nitrite had no effect on these functional characteristics of thylakoids and chloroplasts isolated from plants grown under nitrogen deficiency in the medium.