4种荒漠植物的抗氧化系统和渗透调节的季节变化

Seasonal Change of Antioxidative Enzymes and Osmotic Regulation in Four Desert Plants

研究了塔克拉玛干沙漠南缘4种荒漠植物的水势、渗透调节物质和抗氧化系统的季节变化。结果表明,4种荒漠植物的清晨水势和午后水势的最低值出现在7月,最高值出现在6月,说明在此区域,6月植物的水分状况相对较好,7月植物的水分状况最差。骆驼刺的MDA含量和活性氧(O2-和H2O2)积累随着季节变化均呈上升趋势,表明骆驼刺的膜脂过氧化和膜伤害随季节推进逐渐加剧;柽柳、花花柴和沙拐枣的MDA含量和活性氧积累最高峰值分别出现在7月、7月和8月,说明在水分亏缺最严重的7月和8月,植物面临的膜脂过氧化程度亦最高。4种植物的渗透调节物质积累和抗氧化酶活性的变化,与膜脂过氧化几乎同步。其中,柽柳是以脯氨酸和可溶性糖两者的积累来调节细胞质渗透势以适应极端环境,脯氨酸的积累是沙拐枣应对水分胁迫的主要物质之一,骆驼刺是以可溶性糖的积累来应对水分亏缺,花花柴这两者含量都不高,分析可能是以无机离子作为渗透调节物质。4个月SOD、POD和CAT活性的均值排序均为柽柳>沙拐枣>骆驼刺>花花柴,说明在整个生长季中,柽柳的活性氧积累最为严重,其保护酶SOD、POD和CAT对活性氧的清除均起到关键作用。

The southern fringe of the Taklimakan Desert is an extremely arid region with high temperature,strong solar radiation and very little precipitation.Alhagi sparsifolia,Tamarix ramosissima,Karelinia caspica and Calligonum caputmedusae are dominating species in this region.In order to understand the adaptive mechanisms of the plants to the extreme conditions,we investigated the seasonal change of water potential,osmotic regulation and antioxidative systems of the four desert plants.Results showed that the minimum values of the predawn and afternoon water potential occurred in July,the maximal values appeared in June.MDA and AOS contents of A.sparsifolia increased with the seasonal change,however,the maximal values of T.ramosissima,K.caspica and C.caputmedusae occurred in July and August,respectively.The changes of proline,soluble sugar content and the activities of antioxidative enzymes were the same as MDA.Proline and soluble sugar played an important role in adapting to the extreme environment for T.ramosissima,but their contents were lower in K.caspica,since inorganic ion might be considered as osmotic matter.The order for the activities of SOD,POD and CAT was T.ramosissimaC.caputmedusaeA.sparsifoliaK.caspica.In the whole growing periods,AOS accumulation in T.ramosissima was highest,SOD,POD and CAT played important roles in clearing away AOS.