Sunkar Ramanjulu, Bartels Dorothea, Kirch Hans-Hubert
Institute of Botany, University of Bonn, Kirschallee 1, Bonn 53115, Germany.
Plant J. 2003 Aug;35(4):452-64. doi: 10.1046/j.1365-313x.2003.01819.x.
In plants, oxidative stress is one of the major causes of damage as a result of various environmental stresses. Oxidative stress is primarily because of the excessive accumulation of reactive oxygen species (ROS). The amplification of ROS damage is further stimulated by the accumulation of toxic degradation products, i.e. aldehydes, arising from reactions of ROS with lipids and proteins. Previously, the isolation of dehydration-inducible genes encoding aldehyde dehydrogenases (ALDHs) was reported from the desiccation-tolerant plant Craterostigma plantagineum and Arabidopsis thaliana. ALDHs belong to a family of NAD(P)+-dependent enzymes with a broad substrate specificity that catalyze the oxidation of various toxic aldehydes to carboxylic acids. Analysis of transcript accumulation revealed that Ath-ALDH3 is induced in response to NaCl, heavy metals (Cu2+ and Cd2+), and chemicals that induce oxidative stress (methyl viologen (MV) and H2O2). To investigate the physiological role and possible involvement of ALDHs in stress protection, we generated transgenic Arabidopsis plants overexpressing Ath-ALDH3. Transgenic lines show improved tolerance when exposed to dehydration, NaCl, heavy metals (Cu2+ and Cd2+), MV, and H2O2. Tolerance of transgenic plants is correlated with decreased accumulation of lipid peroxidation-derived reactive aldehydes (as measured by malondialdehyde) compared to wild-type plants. Increased activity of Ath-ALDH3 appears to constitute a detoxification mechanism that limits aldehyde accumulation and oxidative stress, thus revealing a novel pathway of detoxification in plants. We suggest that Ath-ALDH3 could be used to obtain plants with tolerance to diverse environmental stresses.
在植物中，氧化应激是各种环境胁迫造成损害的主要原因之一。氧化应激主要是由于活性氧（ROS）的过度积累。ROS与脂质和蛋白质反应产生的有毒降解产物（即醛类）的积累进一步加剧了ROS的损伤。此前，已报道从耐旱植物车前草叶景天和拟南芥中分离出编码醛脱氢酶（ALDHs）的脱水诱导基因。ALDHs属于NAD(P)+依赖性酶家族，底物特异性广泛，可催化各种有毒醛类氧化为羧酸。转录本积累分析表明，Ath-ALDH3在响应NaCl、重金属（Cu2+和Cd2+）以及诱导氧化应激的化学物质（甲基紫精（MV）和H2O2）时被诱导。为了研究ALDHs在胁迫保护中的生理作用及可能的参与情况，我们构建了过表达Ath-ALDH3的转基因拟南芥植株。转基因株系在暴露于脱水、NaCl、重金属（Cu2+和Cd2+）、MV和H2O2时表现出更高的耐受性。与野生型植株相比，转基因植物的耐受性与脂质过氧化衍生的活性醛（通过丙二醛测量）积累减少相关。Ath-ALDH3活性的增加似乎构成了一种解毒机制，可限制醛类积累和氧化应激，从而揭示了植物中一种新的解毒途径。我们认为Ath-ALDH3可用于培育对多种环境胁迫具有耐受性的植物。
