DISSECTION OF OXIDATIVE STRESS TOLERANCE USING TRANSGENIC PLANTS
DISSECTION OF OXIDATIVE STRESS TOLERANCE USING TRANSGENIC PLANTS
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DOI：
10.1104/pp.107.4.1049
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发表时间：
1995-04-01
期刊：
影响因子：
7.4
通讯作者：
ALLEN, RD
中科院分区：
文献类型：
--
作者：
ALLEN, RD
环境胁迫是植物生产力的主要限制因素。应激暴露对植物造成的许多伤害都与细胞水平的氧化损伤有关。臭氧污染造成的森林和作物的广泛损失是氧化应激的一个非常明显的例子（见Tingey等人，1993年的综述），但与寒冷或干旱时期有关的氧化损伤造成的不太明显的损失也在生长季节累积的渐进挫折中得到重视。胁迫过程中，植物组织中ROIs的产生增加，组织氧化损伤增加，表明了ROIs在植物胁迫损伤中的作用。在植物中，高能量的光合作用反应和充足的氧气供应使叶绿体成为特别丰富的roi来源。高光强可导致PSI过度降低，CO、固着跟不上，NADP+池减少。在这些条件下，O可以与PSI竞争电子，从而通过Mehler反应生成roi。当CO固定受到环境条件的限制时，例如低温或低CO、可用性（关闭气孔）、过度PSI降低和ROI产生增加，即使在中等光照强度下也可能发生。从叶绿体中有效去除roi是至关重要的，因为低至10 p~的H、O浓度可以抑制50%的光合作用（Kaiser, 1979）。虽然0，和H， O本身的毒性相对较低，但通过Haber-Weiss反应，它们的金属依赖性转化为高毒性的0 - H被认为是与这些分子相关的大部分生物损伤的原因。植物叶绿体的抗氧化系统包括SOD和APX等酶，以及抗坏血酸和谷胱甘肽等非酶成分。提出的叶绿体清除ROI的途径如图1所示（Asada, 1994）。超氧自由基是由分子氧在PSI下通过梅勒反应还原而产生的。这个* O，-被与类囊体相关的SOD迅速分解为H， O。生成的氢氧是
Environmental stress is the major limiting factor in plant productivity. Much of the injury to plants caused by stress exposure is associated with oxidative damage at the cellular level. Widespread losses of forests and crops due to ozone pollution provide a highly visible example of oxidative stress (see Tingey et al., 1993, for a review), but less obvious losses caused by oxidative damage associated with periods of cold or drought also take their to11 in the accumulation of incremental setbacks during a growing season. The role of ROIs in plant stress damage is indicated by the increased production of ROIs and the increased oxidative damage in tissues during stress. In plants, the highly energetic reactions of photosynthesis and an abundant oxygen supply make the chloroplast a particularly rich source of ROIs. High light intensity can lead to excess reduction of PSI so that CO, fixation cannot keep pace and NADP+ pools are reduced. Under these conditions, O, can compete for electrons from PSI, leading to the generation of ROIs through the Mehler reaction. When CO, fixation is limited by environmental conditions such as cold temperatures or low CO, availability (closed stomata), excess PSI reduction and increased ROI production can occur even at moderate light intensities. Efficient remova1 of ROIs from chloroplasts is critical, since H, O, concentrations as low as 10 p~ can inhibit photosynthesis by 50%(Kaiser, 1979). Although the toxicity of-0,-and H, O, themselves is relatively low, their metal-dependent conversion to the highly toxic-0H via the Haber-Weiss reaction is thought to be responsible for the majority of the biological damage associated with these molecules.Antioxidant systems of plant chloroplasts include enzymes such as SOD and APX, and nonenzymatic components such as ascorbic acid and glutathione. The proposed ROI scavenging pathway of chloroplasts is shown in Figure 1 (Asada, 1994). Superoxide radicals are produced by the reduction of molecular oxygen at PSI via the Mehler reaction. This* O,-is rapidly dismuted to H, O, by SOD that is associated with the thylakoid. The H, O, produced is