Role of light in the regulation of the nitrate reductase level in wheat (Triticum aestivum)

The relationship between light and NR synthesis was studied in excised wheat leaves. In light, there was a 14 fold increase in the NR level as compared to the dark controls. Sucrose did not have any effect on NR synthesis. In the dark, a significant amount of intracellular nitrate was detected, but there was very little NR activity. Measurement of the decay rates of NR in the dark and light showed that NR activity disappeared faster in light than in the dark. Exposure to short durations of blue, red and white light caused an increase in the NR synthesis. Further, this response was found to be phytochrome controlled. We propose that the process of nitrate reduction influences NR synthesis