Abstract
Nitrate transporter (NRT) mediates the first step of nitrate assimilation. Plants have two distinct types of NRT; NRT2 type NRT is distributed widely among both procaryotes and eucaryotes, whereas NRT1, which belongs to the peptide transporter family, has been found only in higher plants. To study the structure-function relationships of NRT2, we cloned NRT2 cDNAs from the moss Physcomitrella patens, which is amenable to gene manipulation through homologous recombination. In the phylogenetic tree, the five NRT2 homologs identified from the moss are clustered between green algal and vascular plant NRT2s, with stronger similalities to the plant NRT2s. The serine residues presumed to be involved in regulation of NRT2 are conserved in the moss NRT2 sequences, and mRNA expression was induced by nitrate as in higher plants. These data suggest that P. patens is a good model organism to be used for studies on regulation of plant NRT2.
