Abstract
Nitrogen (N) is one of the most important nutrients for plants; its availability often limits plant growth and productivity both in natural and agricultural systems. Plants have evolved a set of responses to adapt to low-N conditions. However, little is known about the molecular basis of these responses. Here we characterized NRT2.4 , which encodes a high-affinity nitrate transporter, as a putative component involved in plant adaptation to low-N conditions in Arabidopsis. Expression analyses revealed that NRT2.4 is induced as nitrogen availability getting scarce and repressed by supplement with various nitrogen species (NO3-, NH4+, and GLN). Transgenic plants harboring promoter-GFP fusion gene revealed that NRT2.4 is preferentially expressed in epidermis of lateral roots, indicating that NRT2.4 plays a role in acquisition of nitrate under N-limiting conditions. To further investigate the role of NRT2.4 , we characterized a T-DNA insertional mutant. The mutant showed reduction in nitrate uptake compared with WT and this was evident only in plants grown under the N-limiting condition. Together, these results suggest that NRT2.4 is involved in adaptation to low-N conditions.
