HIGH-LEVELS OF ANTIOXIDANT ENZYMES CORRELATE WITH DELAYED SENESCENCE IN NONNETTED MUSKMELON FRUITS

We investigated the senescence process in two nonnetted muskmelon (Cuc umis melo L.) varieties Clipper and Jerac differing in their storage l ife. Our results indicate that senescence in Jerac (the short-storage- life variety, less than 7 d) is the result of lipid peroxidation by fr ee radicals, membrane phospholipid breakdown, and a drop in the level of antioxidants, resulting in increased membrane leakiness. By contras t, evidence is presented that the high levels of two enzymes implicate d in antioxidative defence, superoxide dismutase (SOD) and catalase, c ombined with changes in the three different classes of SOD during the storage stage, are involved in delaying the senescence process in Clip per and this could explain, at least, to some extent, the long storage life of Clipper (longer than 14 d).