Guo Feng-Xia, Zhang Man-Xiao, Chen Yuan, Zhang Wei-Hua, Xu Shi-Jian, Wang Jian-Hui, An Li-Zhe
Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, China.
Cryobiology. 2006 Apr;52(2):241-50. doi: 10.1016/j.cryobiol.2005.12.001. Epub 2006 Jan 19.
Chorispora bungeana Fisch. & C.A. Mey (Crucifer) is a rare alpine subnival plant surviving sudden snowstorms. In this paper, we have attempted to explore possible roles of autoxidation rate (AR) and the antioxidant enzymes associated with cryoprotective mechanisms in the plant cells. The results showed that when the suspension cultures growing at 25 degrees C were suddenly exposed to -8 degrees C for 15 days, 2,3,5-triphenyltetrazolium chloride reduction was not affected within 9 days and AR remained at a low level in comparison with controls. This indicated that the cells maintained considerable amounts of soluble protein and the integrity of the cell membranes was intact during the whole freezing test. Furthermore, on average, the activity of antioxidant enzymes such as superoxide dismutase, dehydroascorbate reductase, ascorbate peroxidase and glutathione reductase were prominently enhanced in the freezing-stressed cells. Peroxidase activity significantly increased soon after freezing, possibly to make up for the early decrease of catalase activity in the cells. Statistical analysis showed negative correlations between resistance to rapid freezing and antioxidant enzyme activity in the cultured cells after exposure from 25 to -8 degrees C, indicating that the reduction of cell viability with freezing activates a combination of antioxidant enzymes that results in intact cells. All of these findings suggest a synergy between these antioxidant enzymes, leading to a low autoxidation rate that contributes to the protection of the cell membranes and plays an important role in the resistance of suspension cultured cells of C. bungeana to sudden freezing.
Bunge 离子芥（十字花科）是一种罕见的高山亚冰雪植物，能在突如其来的暴风雪中存活。在本文中，我们试图探究自氧化速率（AR）以及与植物细胞抗冻保护机制相关的抗氧化酶可能发挥的作用。结果表明，当在25℃下生长的悬浮培养物突然暴露于-8℃达15天时，2,3,5-三苯基氯化四氮唑还原在9天内未受影响，并且与对照相比AR保持在较低水平。这表明在整个冷冻试验期间细胞维持了相当数量的可溶性蛋白质，并且细胞膜的完整性保持完好。此外，平均而言，超氧化物歧化酶、脱氢抗坏血酸还原酶、抗坏血酸过氧化物酶和谷胱甘肽还原酶等抗氧化酶的活性在冷冻胁迫的细胞中显著增强。过氧化物酶活性在冷冻后不久显著增加，可能是为了弥补细胞中过氧化氢酶活性的早期下降。统计分析表明，在从25℃暴露于-8℃后，培养细胞的快速冷冻抗性与抗氧化酶活性之间呈负相关，这表明冷冻导致的细胞活力降低激活了多种抗氧化酶，从而使细胞保持完整。所有这些发现表明这些抗氧化酶之间存在协同作用，导致自氧化速率较低，这有助于保护细胞膜，并在 Bunge 离子芥悬浮培养细胞对突然冷冻的抗性中发挥重要作用。
