The Effect of Inhibitors of Photosynthetic and Respiratory Electron Transport on Nitrate Reduction and Nitrite Accumulation in ExcisedZ. maysL. Leaves

Abstract

The assimilation of nitrate and nitrite under dark and light conditions in Zea mays L. leaves was investigated. Nitrate was assimilated under dark-aerobic conditions. Anaerobiosis stimulated nitrate reduction and nitrite accumulation under dark conditions. Vacuum infiltration of inhibitors of respiratory electron transport, antimycin A and rotenone, stimulated nitrate reduction and nitrite accumulation under dark-aerobic conditions. Vacuum infiltration of low concentrations of PCP, DNP and mCCCP depressed nitrate reduction and nitrite accumulation under dark-aerobic conditions, whereas, infiltration of higher concentrations stimulated nitrate reduction and nitrite accumulation. The greatest level of nitrate and nitrite reduction occurred under light conditions. The inhibitor of photosynthetic electron transport, DCMU, stimulated the accumulation of nitrite in the light, but decreased nitrate reduction. When the inhibitors of respiratory electron transport antimycin A and rotenone, were supplied together with DCMU in the light, nitrite accumulation was enhanced. Low concentrations of mCCCP decreased both nitrate reduction and nitrite accumulation under light conditions when supplied with DCMU.