Involved in the pathway of sideretin biosynthesis from feruloyl CoA, a redox-active catecholic metabolite exuded by roots in response to iron deficiency in order to facilitate the uptake of iron; this pathway consists in the successive conversion from feruloyl CoA to scopoletin, from scopoletin to fraxetin and from fraxetin to sideretin. Catalyzes the biosynthesis of fraxetin via scopoletin hydroxylation. 2-oxoglutarate + O2 + scopoletin = CO2 + fraxetin + succinate Binds 1 Fe(2+) ion per subunit. Phenylpropanoid metabolism. Expressed in both primary and lateral roots under iron-deficient conditions, except in apical root zones, and mostly in the root epidermal layer. Strongly induced by iron deficiency, mainly in roots. Accumulation of scopoletin, but loss of sideretin root secretion in response to iron deficiency. Impaired iron-uptake ability at elevated pH leading to chlorotic and stunted plants; this phenotype is rescued by fraxetin and sideretin treatments, but not by scopoletin treatment. Belongs to the iron/ascorbate-dependent oxidoreductase family. Extended C-terminus.