ABSTRACT
The nitrate assimilation pathway is of great importance for higher plants as they acquire most of their organic nitrogen through nitrate uptake from the soil and reduction. Transgenesis has been widely used for the study of the regulation of this pathway. This review will focus on the studies that were performed on the first two enzymes of the nitrate assimilation pathway, namely nitrate and nitrite reductases. For example, transgenic plants expressing deregulated forms of nitrate reductase were obtained and have been invaluable tools for the analysis of transcriptional and post-transcriptional regulation but were also very useful in trying to improve nitrate assimilation in plants. Also transgenic plants carrying transcriptional or translational fusions of the nitrate or nitrite reductase gene promoters were of great help in the understanding of the regulation of these genes by environmental factors such as nitrate or light.
