In order to thoroughly understand the mechanism of drought resistance in plants at DNA level, the DNA damage of two ecotypes of reeds ( Phragmites communis T.) stressed by PEG 6000 was analyzed by means of fluorescence analysis of DNA unwinding (FADU). The results showed that the residual double strand DNA percentages (dsDNA%) in dune reed (DR) were significantly higher than those in swamp reed (SR) treated with either 20% or 30% PEG 6000. This meant that the DNA of DR was less damaged in comparison with SR. Similarly, DR resisted DNA damage more strongly than SR as reactive oxygen species (ROS) increased by adding ROS producers diethyldithio carbamate (DDC), H2O2 and Fe2+ of different concentrations. Meanwhile, treating PEG stressed SR with ROS scavengers such as dimethyl sulphoxide (DMSO) and ascorbic acid (Vc) resulted in the reduction of DNA damage, suggesting that ROS could cause DNA damage. In addition, the DNA repair for water-stressed reeds indicated that DR repaired DNA damage much faster and more completely. This might be the first indication that drought stress led to DNA damage in plants and that drought resistance of plants was closely related to DNA damage and repair.
水分胁迫引起的两种不同生态型芦苇的DNA损伤与修复
王俊刚1 张承烈2*
（1. 浙江林学院资源环境系，浙江临安311300；2. 兰州大学生命科学学院，兰州730000）
摘要：利用DNA解链荧光分析 (FADU)法检测两种不同生态型芦苇 (Phragmitescommunis T .)在PEG 6 0 0 0胁迫处理后的DNA损伤。结果表明 :无论是 2 0 %还是 30 %PEG 6 0 0 0胁迫处理 ,耐旱性强的沙丘芦苇的DNA损伤都比耐旱性弱的沼泽芦苇较轻。利用不同浓度的二乙基二硫代氨基甲酸钠 (DDC)、H2 O2 、FeSO4 以增加芦苇的 3种活性氧(O2 -·、H2 O2 、·OH)的实验也同样显示出沙丘芦苇抵抗水分胁迫引起的DNA损伤的能力较强。同时 ,当加入外源活性氧清除剂二甲基亚砜 (DMSO)、抗坏血酸 (Vc)时 ,水分胁迫处理的芦苇DNA损伤表现出不同程度的减轻。当PEG胁迫处理的芦苇复水后 ,DNA损伤随复水时间延长而逐渐减轻 ,但沙丘芦苇的DNA损伤修复较快而完全。实验初步证明 :水分胁迫可引起植物体内DNA损伤且该损伤与活性氧有关 ,植物的抗旱性与DNA损伤及修复密切相关。
关键词： 沙丘芦苇；沼泽芦苇；水分胁迫；活性氧；植物体内DNA损伤；DNA修复
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