葡萄幼苗在温度逆境交叉适应过程中活性氧及抗氧化酶的变化

Changes of Active Oxygen and Antioxidant Enzymes in Leaves of Young Grape Plants During Cross Adaptation to Temperature Stress

为探讨葡萄幼苗对温度逆境产生交叉适应性的抗氧化机制,以2年生‘京秀’葡萄(Vitis vinifera L.‘Jingxiu’)幼苗为试材,分析了交叉适应性诱导过程中叶片细胞O_2^-和H_2O_2等活性氧分子,膜脂过氧化以及过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)等抗氧化酶活性的适应性变化。结果表明,0℃低温胁迫和45℃高温胁迫进程中,幼苗叶片细胞膜系统受到严重伤害,表现为CAT、POD和SOD等抗氧化酶活性降低,膜脂过氧化产物丙二醛(MDA)含量明显升高,活性氧增加。经过高温锻炼的幼苗,在低温胁迫期间抗氧化酶活性增强,O_2^-产生速率和H_2O^2含量先上升后下降,MDA含量和膜透性也比对照有明显降低且相对稳定;经过低温锻炼的幼苗,在高温胁迫期间,上述各项指标的变化规律与高温锻炼幼苗在低温胁迫期间的变化趋势相似。因此认为,高温锻炼诱导的葡萄幼苗的抗冷性和低温锻炼诱导的耐热性有着相似的抗氧化保护机制。

To explore the mechanism of cross adaptation to different temperature stresses in plants, the influence of heat acclimation（HA）on chilling resistance and cold acclimation（CA）on heat tolerance and the parallel changes in antioxidant system in leaves of two-year-old young grape（Vitis vinifera L.‘Jingxiu’） plants were studied with comparative methods. Changes in activated oxygen especially O2^↑-· and H2O2, malondialdehyde（MDA）content and activities of enzyme involving cell defense were detected. The results showed that the cell membrane was damaged by cold stress（0℃）or heat stress（45℃）in leaves. Activities of cell defense enzymes such as catalase（CAT）,peroxidase（POD）and superoxide dismutase（SOD）were gradually decreased, but the O2^↑-· generation rate and H2O2 content, relative membrane leakage and MDA content were rapidly increased under temperature stresses. However, in HA plants, the O2^↑-· generation rate and H2O2 content increased to a certain degree and then decreased, the relative membrane leakage and MDA concentration maintained relative lower than those in control plants under cold stress. It is important that, the change tendency of all those indexes in CA plants under heat stress was consistent with that in HA plants under cold stress. These results suggested that a similar antioxidant mechanism was involved in the chilling resistance induced by HA and heat tolerance induced by CA.