Involved in high-affinity nitrate transport. Controls nitrate content in seeds. Expressed in seeds, leaves and shoots. Lower expression in roots. Expressed mainly at the end of seed maturation when the tissue is completely dry. Not induced by nitrate or by growth on low nitrate concentration. Down-regulated by imbibition. No visible phenotype during vegetative growth. No effect on root nitrate influx. Decreased nitrate content in mature seeds and delayed germination. Belongs to the major facilitator superfamily. Nitrate/nitrite porter (TC 2.A.1.8) family.