Nitrate transporter involved in the constitutive high-affinity transport system (cHATS) under long-term N starvation conditions (PubMed:15107992, PubMed:25065551). Predominantly expressed in roots of nitrate-deprived plants as a 150 kDa molecular complex with NRT3.1 representing the major contributor to cHATS influx (PubMed:25474587). The principal role of this cHATS is to enable roots previously deprived of nitrate to absorb this ion and initiate induction of nitrate-inducible genes (PubMed:25474587). Not involved in transfer of nitrate from roots to shoots (PubMed:25474587). Contributes to phloem loading of nitrate in shoots during N starvation, but not required for growth and nitrate uptake in young plants (PubMed:25065551). Required for the nitrate uptake-independent plant growth promotion and lateral root response to the rhizospheric Phyllobacterium (PubMed:23398541). Might be involved in the transfer of nitrate from stored pools to cytoplasm (PubMed:15107992). Oligomeric molecular complex with NRT3.1 (PubMed:22432443, PubMed:25474587). Expressed in roots, shoots and seeds (PubMed:12668777, PubMed:17540716). Expressed in leaves (PubMed:23398541). Expressed in root hair zone of the primary root and the lateral roots, but not in the lateral root tip or in older parts of the roots (PubMed:25065551). Detected mainly in the epidermis and the cortex (PubMed:25065551). Expressed in shoots only in higher-order veins (PubMed:25065551). Down-regulated by nitrate and by imbibition (PubMed:12668777, PubMed:17540716, PubMed:25474587). No induction by growth on low nitrate concentration, but strong induction in mutant with disruption in both NRT2.1 and NRT2.2 (PubMed:15107992). However, this overexpression could not restore the nitrate influx (PubMed:15107992). Induced under long-term nitrogen starvation (PubMed:25065551). Strongly up-regulated upon inoculation with the plant growth-promoting rhizobacteria Phyllobacterium (PubMed:16160849). Loss of plant growth and root system architecture responses to the rhizospheric Phyllobacterium (PubMed:23398541). Decreased nitrate uptake in the high-affinity range (PubMed:25065551, PubMed:25474587). Belongs to the major facilitator superfamily. Nitrate/nitrite porter (TC 2.A.1.8) family.