Oxidative stress and antioxidant systems in tomato fruits during storage

Tomato varieties ARTH-3 (long shelf-life; 14-15 days) and Sel-7 (short shelf-life; 5-7 days), harvested at color turning stage, were stored in open trays at 10, 25 and 35C and sampled at two day intervals until complete deterioration. Variety ARTH-3 could be stored at all the temperatures for ten days, while Sel-7 could tolerate 35C only for four days. However, at 10 and 25C, it could be stored for six days. In both varieties, lipoxygenase (LOX) activity, malondialdehyde (MDA) value and H₂O₂ content increased during storage. Increase in storage temperature further enhanced the activity of LOX, and also increased MDA value and H₂O₂ content. Sel-7 had higher values for these parameters than ARTH-3. Activities of enzymes responsible for scavenging reactive oxygen species (ROS) viz., Superoxide dismutase, peroxidase, ascorbate peroxidase, glutathione reductase and catalase decreased continuously during storage. With increase in temperature, the activities of these enzymes further decreased significantly in both varieties. Sel-7 had significantly lower activities of ROS scavenging enzymes than ARTH-3 throughout the storage period. These results suggest that fruits stored at higher temperature are subjected to severe oxidative damage leading to extensive membrane damage and loss of tissue structure.