Involved in the biosynthesis of mugineic acid family of phytosiderophores. Hydroxylates the C-3 positions of mugineic acid (MA) and 2'-deoxymugineic acid (DMA). May be involved in boron tolerance. 2-oxoglutarate + mugineate + O2 = 3-epihydroxymugineate + CO2 + H(+) + succinate 2'-deoxymugineate + 2-oxoglutarate + O2 = 3-epihydroxy-2'-deoxymugineate + CO2 + H(+) + succinate Binds 1 Fe(2+) ion per subunit. Expressed in roots, but not in leaves. Up-regulated by manganese and zinc deficiency or by excess NaCl. Down-regulated by iron. Belongs to the iron/ascorbate-dependent oxidoreductase family.