Required for nitrate signaling. Regulates expression of the nitrate-responsive genes NIA1, NIR1, NRT2.1 and NPF6.3/NRT1.1. Interacts with NLP7. Highest expression levels in leaves and roots, and lowest in flowers and siliques. Also expressed in stems and seedlings. Also expressed in stromata. In flowers, expressed in the pistil, junction of filament and anther, and vascular tissue of sepals and petals. In roots, expressed in stelar cells including the pericycle, phloem and parenchyma cells. In leaves, expressed in bundle sheath, phloem and parenchyma cells of the vascular tissue. Under high nitrate concentration, seedlings are slightly smaller and display later flowering than wild-type. Under low nitrate concentration, seedlings appear normal. Nitrate accumulation of the seedlings and roots is significantly lower than in wild-type, however no difference of nitrate accumulation in leaves. Nitrate content differences in roots and leaves may be due to the reduced expression of NPF6.3/NRT1.1 in roots and the increased expression of NPF7.2/NRT1.8 in leaves. After nitrate treatment, altered expression of many genes involved in nitrogen-related clusters including nitrate transport and response to nitrate. Truncated N-terminus.