摘要
对青杨叶片进行不同时间的零上低温（２℃±１℃）胁迫处理，研究其中Ｏ＝２产生速率、ＳＯＤ和ＣＡＴ活性水平和ＭＤＡ含量的相关变化，并相应测定与之相伴随发生的膜透性和叶水势的改变。结果表明，青杨叶片的Ｏ＝２产生速率随低温胁强的增强而提高，当胁强增大到一定范围时，Ｏ＝２产生速率又趋下降。ＭＤＡ的含量变化趋势相似；ＳＯＤ和ＣＡＴ活性水平也与Ｏ＝２的变化相一致；细胞质膜透性的增大和叶水势的降低则均与低温胁强的提高呈正相关。综观上述结果，证明青杨叶细胞的低温胁迫伤害系由Ｏ＝２诱发的膜脂过氧化，破坏了细胞膜系统所致。
It is well know that the chilling stress may induce oxygen free radical generation and cause various degree injuries to some plant species. In this paper the leaves of P.cathayana Rehd. were treated with different chilling stress to study the mechanism of leaf injury. The results showed that generation rate of superoxide free radical(O = 2) increased with the increase in chilling stress time. The stress strength was in direct proportion to the amount of O = 2 generation between 12h to 24h. The trend of change in MDA contents was similar to that in O = 2 generation rate. In certain range of stress strength, the activity levels of SOD and CAT corresponded to the change in O = 2. There was a positive corelation between increase of cytoplasmic membrane permeability, leaf water potential decrease and increment of MDA content. The conclusion obtained from this study may be that chilling stress damage of leave im P.cathayana is caused by membrane-lipid peroxidation fristly, meanwhile increase in MDA content, and cytoplasina system destruction.
关键词
青杨
低温胁迫
丙二醛
叶片
水势
保护酶
Chilling stress Superoxide free radial Membrane-lipid peroxidation Malondialdehyde(MDA) Superoxide dismutase(SOD) Populus cathayana Rehd.
