Involved in melatonin degradation (PubMed:25728912). Catalyzes the hydroxylation of melatonin to produce 2-hydroxymelatonin (PubMed:25728912). 2-oxoglutarate + melatonin + O2 = 2-hydroxymelatonin + CO2 + succinate Binds 1 Fe(2+) ion per subunit. Optimum pH is 7.4. Optimum temperature is 45 degrees Celsius. Expressed in shoots. Induced by cadmium. Belongs to the iron/ascorbate-dependent oxidoreductase family.