Contribution of Oxidative Stress to the Development of Cold-Induced Damage to Leaves of Chilling-Sensitive Plants: 2. The Activity of Antioxidant Enzymes during Plant Chilling

Changes in the activities of cytosolic superoxide dismutase, ascorbate peroxidase, and catalase were studied in 7–11-day-old seedlings of maize (Zea mays L.), cucumber (Cucumis sativus L.), millet (Panicum miliaceum L.), and etiolated potato (Solanum tuberosum L.) sprouts. The assays were performed immediately after chilling at 2°C for 1–24 h and one day after 24-h chilling. During the first 1–2 h of chilling, enzyme activities were substantially reduced in chilling-sensitive plants (cucumber and maize). Further chilling resulted in a gradual increase in the enzyme activities to a degree dependent on plant species. One day after the plants were returned to a high temperature, the enzyme activities were restored to an initial level or exceeded it (excluding maize superoxide dismutase). In the potato (cold-resistant species), we did not observe any regular changes in the activities of antioxidant enzymes. On the whole, the activities of these enzymes inversely depended on species cold-resistance. The conclusion is that one of the cold-resistance factors is the capacity of antioxidant enzymes to maintain their activities during chilling and restore them relatively rapidly after plant transfer to warm conditions.