EFFECTS OF WOUND STRESS BY SLICING SWEET- PEPPER FRUITS ON ASCORBIC-ACID METABOLISM

The effects of wound stress by slicing sweet pepper fruits 'Golden Bel l' on ascorbic acid metabolism were investigated. 1. The ascorbic acid contents in sliced tissue of mature green and ripe yellow pepper frui ts stored at 20 degrees C were not changed by wounding; although the d ehydroascorbic acid contents increased after wounding, that level was maintained constant during the subsequent storage period. 2. The level of hydrogen peroxide in sliced tissues stored at 20 degrees C was sli ghtly lower than that of whole fruit; thereafter the hydrogen peroxide content in sliced tissues increased to the equal that in whole fruit within 24 hours of storage. 3. In both mature green fruit and ripe yel low fruit, the activities of ascorbate peroxidase were not influenced by wounding. The activities of monodehydroascorbate reductase in slice d yellow ripe fruit tissues stored at 20 degrees C increased during 12 hours after wounding, thereafter they decreased. On the other hand, t he activities of monodehydroascorbate reductase in sliced mature green fruit tissues stored at 20 degrees C: were not influenced by wounding . The activities of dehydroascorbate reductase in sliced tissue prepar ed from mature green fruit and ripe yellow fruit increased during 12 h ours after cutting, and then decreased during the subsequent storage p eriod. 4. The activities of catalase, glutathione reductase, and L-gal actono-gamma-lactone dehydrogenase in sliced tissues prepared from mat ure green fruit and ripe yellow fruit increased after cutting, and the n decreased during subsequent storage period. Our results suggest that wound stress by cutting activates the biosynthesis of ascorbic acid a nd reductases on ascorbic acid metabolism, so that the level of ascorb ic acid in sweet pepper fruits remains high.