Involved in the biosynthesis of mugineic acid family of phytosiderophores. Hydroxylates the C-2' positions of 2'-deoxymugineic acid (DMA) and 3-epihydroxymugineic acid (epiHDMA). May be involved in boron tolerance. 2'-deoxymugineate + 2-oxoglutarate + O2 = CO2 + mugineate + succinate Binds 1 Fe(2+) ion per subunit. Up-regulated by iron deficiency and down-regulated by iron. Not induced by anaerobic conditions. The N-terminus is blocked. Belongs to the iron/ascorbate-dependent oxidoreductase family.