四合木和霸王幼苗抗氧化系统对干旱胁迫的响应差异

Response of Antioxidant System in Leaves of Tetraena mongolica and Zygophyllum xanthoxylon Seedlings to Drought Stress

以室内培养的珍稀濒危植物四合木及其近缘种霸王的幼苗为材料,用不同浓度PEG模拟不同程度的干旱胁迫,探讨2种植物幼苗主要抗氧化酶活性和抗氧化物质含量对干旱胁迫的响应特征。结果表明:(1)随着干旱胁迫强度的增加,四合木和霸王幼苗的干、鲜重及含水量逐渐减少,而MDA含量逐渐升高;四合木抗氧化酶SOD、POD、CAT、AsA-POD和GR活性以及抗氧化剂AsA和GSH含量均呈先升后降的趋势,而霸王AsA-POD和GR活性及抗氧化剂AsA和GSH含量呈上升趋势,SOD、POD和CAT活性呈先升后降的趋势,且霸王出现峰值时PEG浓度均高于四合木。(2)同等强度的PEG胁迫,四合木体内MDA积累量所指示的膜质过氧化程度高于霸王,抗氧化酶活性和抗氧化剂含量均分别高于霸王,而地上部鲜重、地上部干重和含水量却低于霸王。研究表明,霸王幼苗体内各种抗氧化酶活性和抗氧化剂含量增加的阈值要高于四合木,能忍耐的干旱胁迫的阈值大于四合木,耐旱性强于四合木;相同程度的干旱胁迫下霸王的耐受性强于四合木。

The experiment was carried out by Tetraena mongolica and its related congener Zygophyllum xanthoxylon seedlings with different concentrations of polyethylene glycol（PEG） to investigate the effects of drought stress on antioxidant enzyme activities and antioxidants of two seedling leaves.The results showed that：（1）With the PEG concentration becoming higher,MDA content increased whereas the fresh weight,dry weight and water content of two seedlings reduced.The antioxidative enzymes（SOD,POD,CAT,AsA-POD and GR） activities and the antioxidants（AsA and GSH） contents of T.mongolica as well as SOD,POD and CAT activities of activities peak of PEG concentration in Z.xanthoxylon was higher than that in T.mongolica.The activities of AsA-POD and GR as well as the AsA and GSH contents of Z.xanthoxylon increased significantly according to the increasing of drought stress.（2）Compared with Z.xanthoxylon,the memberane lipid peroxidation,the antioxidative enzyme activities and the antioxidants contents of T.mongolica were higher,but the fresh weight,dry weight and water content were lower.The result revealed that the increased threshold value of antioxidative enzyme activities and antioxidant contents in Z.xanthoxylon is higher than that in T.mongolica.The results indicated that the ability of resistance against drought stress in Z.xanthoxylon is stronger than that in T.mongolica.The endurance ability of Z.xanthoxylon is stronger than that of T.mongolica in the same degree of drought stress.