植物冻害和氧化胁迫——甘蓝叶冻-融循环中超氧的产生

Freezing injury of plant and oxidative stress-Superoxide generation in freeze-thaw cycles of Cabbage leaf tissues.

为检验植物冻害的发生和氧化胁迫这一假说 ,在冰冻前把氮蓝四唑 (NBT)真空渗入到甘蓝叶圆片中 .在叶圆片冻 融循环中NBT被还原为甲 .把其中的单甲 用乙醇提取出来 ,在分光光度计上比色 ,可作为冻 融循环中产生的氧化胁迫的定量指标 .NBT本身作为氧化剂 ,使冻害稍有增加 .作为冰冻保护剂的二甲基亚砜真空渗入叶圆片使其抗冻性显著增加 ,而NBT还原则显著减少 ,表明二甲基亚砜在保护叶组织免受冻害上的作用和它减缓植物组织氧化胁迫的作用有关 .实验结果支持植物冻害的发生和氧化胁迫有关这一假说 .实验还表明还原NBT的还原剂很可能是超氧阴离子自由基 .

To test the hypothesis that oxidative stress is involved in inducing freezing injury of plants,nitroblue tetrazolium (NBT) was infiltrated into cabbage leaf tissues before they were frozen. NBT was reduced to formazans in freeze thaw cycles. The ethanol extractable mono formazan was measured by a spectrophotometer,and used as a quantitative indicator of oxidative stress that developed during a freeze thaw cycle. NBT per se as an oxidant increased the freezing injury slightly. When Me 2SO as a cryoprotectant was infiltrated into leaf tissue,it apparently enhanced the freezing tolerance,and this is correlated to its ability in ameliorating oxidative stress,as indicated by the partial inhibition of NBT reduction.The results supported the hypothesis that freezing injury of plants is related to oxidative stress. The experiments indicated that it was possible that the reductant of NBT in the freeze thaw cycle was superoxide anion free radical.