干旱胁迫及复水对喀斯特地区柏木幼苗活性氧清除系统的影响

Effects of drought stress and re-watering on the active oxygen scavenging system of Cupressus funebris seedlings in Karst area.

为了解喀斯特地区适生物种柏木对"干旱-复水"环境的适应机制,以柏木实生苗为材料,研究干旱条件下其活性氧清除系统及复水后的修复能力.结果表明:随干旱处理时间的延长,柏木幼苗相对含水量下降,可溶性蛋白含量先增加后降低,丙二醛(MDA)含量升高;胁迫初期(2周)复水后,MDA含量下降到对照水平,而胁迫中期(4周)和末期(6周)的严重干旱复水后不能降至对照水平;干旱胁迫下超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)均持续上升,复水后,SOD活性有所下降,但仍高于对照,POD和CAT在轻度干旱下复水降至对照水平,而重度干旱后复水则下降幅度较小.轻度胁迫能够提高柏木幼苗可溶性蛋白含量,抑制膜脂过氧化,抵抗水分胁迫,且具有很强的自我修复能力,但严重干旱会使其膜结构严重受损,无法完成自我修复.

This paper studied the active oxygen scavenging system of Cupressus funebris seedlings under drought condition and the recovery capability of the system after re-watering,aimed to understand the adaptation mechanisms of C.funebris to the ＇drought and re-watering＇ environment in Karst area.With the increasing time of drought stress,the seedling＇ s relative water content（RWC） decreased,soluble protein concentration increased first and decreased then,and malondialdehyde（MDA） content increased consistently.The MDA content recovered to the level of the control（CK） when re-watering was implemented within 2 weeks of drought,but could not when the re-watering was made after 4 and 6 weeks of drought.Under drought stress,the activities of superoxide dismutase（SOD）,peroxidase（POD）,and catalase（CAT） increased consistently.After re-watering,the SOD activity had somewhat decrease but still remained at a higher level than the CK,and the POD and CAT activities decreased to the CK level when suffered mild stress but had less decrement when suffered severe stress.It was concluded that C.funebris seedlings could resist mild drought stress via increasing their soluble protein concentration and inhibiting membrane lipid peroxidation,but could not resist severe drought stress because of the irreversible damage of their membrane structure.