Alterations of the Enzyme Activities Involved in H₂O₂ Metabolism of Stored Mitsuba (Cryptotaenia japonica Hassk.) Leaves

Abstract

The changes of peroxide content and enzyme activities involved in hydrogen peroxide metabolism of stored mitsuba (Japanese hornwort, Cryptotaenia japonica Hassk. cv. Senkaku) leaves were studied to elucidate the role of peroxides in leaf yellowing. The peroxide content in mitsuba leaves decreased significantly during storage at 25°C. Glycolate oxidase activity increased for the first 2 days of storage at 25°C and then decreased with leaf yellowing, while superoxide dismutase activity showed a decline during storage. Catalase and peroxidase activities decreased in stored mitsuba leaves, the decrease being greater in catalase than in peroxidase. These results suggest that the oxidation process in which the peroxides, including hydrogen peroxide, are involved, might enhance leaf yellowing in stored mitsuba.