Iron transporter involved in the uptake of iron from the rhizosphere across the plasma membrane in the root epidermal layer. May also transport other divalent cations. Expressed in companion cells in the upper region of the root. By iron and zinc deficiency in roots. Plants overexpressing IRT1 show enhanced tolerance to iron deficiency at the seedling stage, elevated content of cadmium, iron and zinc in roots, shoots and mature seeds, and are sensitive to an excess of zinc or cadmium. Belongs to the ZIP transporter (TC 2.A.5) family.