Promoter analysis of high-affinity nitrate transporter genes in Physcomitrella patens

Abstract

High-affinity nitrate transporters of the NRT2 family play a central role in import of nitrate into plant cells. The moss P. patens has eight NRT2 genes, expression of which is activated by nitrate and nitrite, and repressed by glutamine. In an attempt to elucidate the mechanism of the nitrogen-responsive gene regulation in the moss, we are performing promoter analysis of the NRT2;1 and NRT2;3 genes. When fused to a reporter gene, the 2440-bp and 3288-bp sequences of the NRT2;1 and NRT2;3 upstream regions, respectively, promoted nitrate-responsive gene expression. In the case of NRT2;1, the region from position -2440 to -2079 with respect to the transcription start site was shown to be required for the response to both nitrate and nitrite. Similar analysis with the NRT2;3 promoter is in progress.