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Induction of enzymes involved in the Ascorbate-dependent antioxidative system, namely, ascorbate peroxidase, monodehydroascorbate reductase and dehydroascorbate reductase, after exposure to air of rice (Oryza sativa) seedlings germinated under water

Ushimaru, T., Maki, Y., Sano, S., Koshiba, K., Asada, K., Asada, K., Tsuji, H.
Plant & cell physiology 1997 v.38 no.5 pp. 541-549
Oryza sativa, seedlings, seed germination, submergence, anaerobic conditions, hypoxia, oxygen requirement, aerobic conditions, adaptation, ascorbic acid, antioxidants, peroxidase, isozymes, oxidoreductases, dehydroascorbic acid, enzyme activity, kinetics
The activities of enzymes involved in the antioxidative system are lower in rice (Oryza sativa) seedlings that have been germinated under water than in aerobically grown controls and these activities increase when the submerged seedlings are transferred to air. In this study, we examined the changes in protein levels of enzymes implicated in the ascorbate-dependent antioxidative system, namely, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), and dehydroascorbate reductase (DHAR). We found two isozymes of APX and of MDAR, and one form of DHAR in rice. The isozymes of MDAR and DHAR were distributed ubiquitously in rice tissues, but no APX isozyme was found in dry seeds. The levels of all antioxidative proteins were low in submerged seedlings, but repression of their expression was released by transfer of the seedlings to air. However, the levels of some isozymes rose slowly and gradually, while levels of others rose quickly and then fell again.