青椒果实冷害及诱导抗冷性与氧化胁迫关系的研究

Study on Relationship of Chilling Injury and Induced Anti-chilling Injury with Oxidative Stress in Green Pepper Fruits

青椒在9℃下冷藏8w,没有出现冷害,膜透性变化不大。而在2℃下贮藏1w后即出现冷害症状,超过4w发生严重冷害,膜透性迅速上升。与9℃贮藏青椒相比,2℃贮藏青椒的SOD活性降低,而CAT活性降低更多;POD活性也低于9℃贮藏青椒,但7w时骤升至峰值。贮前50℃ 10min或53℃5min热水浸泡处理极显著降低了2℃贮藏青椒的冷害,显著抑制了膜透性的上升。与对照相比,50℃热处理对青椒SOD活性影响不明显而53℃热处理显著提高了3、4和5w时SOD活性。两热处理均极显著提高了青椒 CAT活性,对CAT活性的提高超过SOD。两热处理青椒贮藏过程中POD活性呈缓慢下降趋势,避免了对照组青椒POD活性6w时的显著降低和7 w时的骤然上升。可见青椒的冷害与低温下活性氧清除酶,特别是CAT活性的降低,导致活性氧化代谢失调有关。而贮前热处理通过提高活性氧清除酶特别是CAT活性,维持活性氧代谢的平衡,抑制膜质过氧化,从而减轻了青椒的冷害。

No chilling injury symptom appeared on green pepper fruits and membrane permeability little changed during storage at 9℃ for 8 weeks. But the fruits stored at 2℃ had slight chilling injury symptom only after 1 week and suffered severe chilling injury when the storage duration surpassed 4 weeks with rapid increase in membrane permeability. Compared to pepper fruits at 9 ℃, SOD (Superoxide dimutase)activity of fruits at 2℃ was lowered and CAT (catalase)activity of them decreased much more than SOD. POD (peroxidase)activity of fruits at chilling temperature was lower than that of fruits at 9℃, but increased abruptly to a climax in 7th week. 50℃ hot water dip 10 minutes or 53℃ 5 minute (prestorage heat treatment) significantly alleviated chilling injury and manifestly hindered increase in membrane permeability of pepper fruits stored at 2℃. Compared to control, 50℃ heat treatment had no obvious effect on SOD activity and 53℃ significantly improved SOD activity in week 3, week 4 and week 5. Both heat treatments significantly elevated CAT activity and the effect of them in increasing CAT activity was more obvious than SOD. POD activity of fruits heated declined slowly without significant drop and abrupt increase happened in control fruits during storage at 2℃. It suggested that the chilling injury of green pepper fruits during storage at chilling temperature had relationship with decrease in activated oxygen scavenging enzyme activity, especially the decrease in CAT, resulting in misbalanced metabolisms of activated oxygen. Prestorage heat treatment alleviated chilling injury of green pepper fruits by elevating the activity of activated oxygen scavenging enzyme, especially CAT, maintaining metabolism balance of activated oxygen and therefore preventing mem- brane lipid peroxidation.