Rao M V, Paliyath G, Ormrod D P, Murr D P, Watkins C B
Department of Horticultural Science, University of Guelph, Ontario, Canada.
Plant Physiol. 1997 Sep;115(1):137-49. doi: 10.1104/pp.115.1.137.
We investigated how salicylic acid (SA) enhances H2O2 and the relative significance of SA-enhanced H2O2 in Arabidopsis thaliana. SA treatments enhanced H2O2 production, lipid peroxidation, and oxidative damage to proteins, and resulted in the formation of chlorophyll and carotene isomers. SA-enhanced H2O2 levels were related to increased activities of Cu,Zn-superoxide dismutase and were independent of changes in catalase and ascorbate peroxidase activities. Prolonging SA treatments inactivated catalase and ascorbate peroxidase and resulted in phytotoxic symptoms, suggesting that inactivation of H2O2-degrading enzymes serves as an indicator of hypersensitive cell death. Treatment of leaves with H2O2 alone failed to invoke SA-mediated events. Although leaves treated with H2O2 accumulated in vivo H2O2 by 2-fold compared with leaves treated with SA, the damage to membranes and proteins was significantly less, indicating that SA can cause greater damage than H2O2. However, pretreatment of leaves with dimethylthiourea, a trap for H2O2, reduced SA-induced lipid peroxidation, indicating that SA requires H2O2 to initiate oxidative damage. The relative significance of the interaction among SA, H2O2, and H2O2-metabolizing enzymes with oxidative damage and cell death is discussed.
我们研究了水杨酸（SA）如何增强过氧化氢（H₂O₂）以及SA增强的H₂O₂在拟南芥中的相对重要性。SA处理增强了H₂O₂的产生、脂质过氧化以及对蛋白质的氧化损伤，并导致叶绿素和类胡萝卜素异构体的形成。SA增强的H₂O₂水平与铜锌超氧化物歧化酶活性的增加有关，且与过氧化氢酶和抗坏血酸过氧化物酶活性的变化无关。延长SA处理会使过氧化氢酶和抗坏血酸过氧化物酶失活，并导致植物毒性症状，这表明H₂O₂降解酶的失活是过敏细胞死亡的一个指标。单独用H₂O₂处理叶片未能引发SA介导的事件。尽管与用SA处理的叶片相比，用H₂O₂处理的叶片在体内积累的H₂O₂增加了2倍，但对膜和蛋白质的损伤明显较小，这表明SA比H₂O₂能造成更大的损伤。然而，用二甲基硫脲（一种H₂O₂捕捉剂）预处理叶片可减少SA诱导的脂质过氧化，这表明SA需要H₂O₂来引发氧化损伤。本文讨论了SA、H₂O₂和H₂O₂代谢酶之间的相互作用在氧化损伤和细胞死亡中的相对重要性。
