Baier M, Noctor G, Foyer C H, Dietz K J
Stoffwechselphysiologie und Biochemie der Pflanzen, Universität Bielefeld, Universitätsstrabetae 25, 33615 Bielefeld, Germany.
Plant Physiol. 2000 Oct;124(2):823-32. doi: 10.1104/pp.124.2.823.
The aim of this study was to characterize the effect of decreased 2-cysteine peroxiredoxin (2-CP) on the leaf anti-oxidative system in Arabidopsis. At three stages of leaf development, two lines of transgenic Arabidopsis mutants with decreased contents of chloroplast 2-CP were compared with wild type and a control line transformed with an empty vector. Glutathione contents and redox state were similar in all plants, and no changes in transcript levels for enzymes involved in glutathione metabolism were observed. Transcript levels for chloroplastic glutathione peroxidase were much lower than those for 2-CP, and both cytosolic and chloroplastic glutathione peroxidase were not increased in the mutants. In contrast, the foliar ascorbate pool was more oxidized in the mutants, although the difference decreased with plant age. The activities of thylakoid and stromal ascorbate peroxidase and particularly monodehydroascorbate reductase were increased as were transcripts for these enzymes. No change in dehydroascorbate reductase activity was observed, and effects on transcript abundance for glutathione reductase, catalase, and superoxide dismutase were slight or absent. The results demonstrate that 2-CP forms an integral part of the anti-oxidant network of chloroplasts and is functionally interconnected with other defense systems. Suppression of 2-CP leads to increased expression of other anti-oxidative genes possibly mediated by increased oxidation state of the leaf ascorbate pool.
本研究的目的是表征叶绿体2-半胱氨酸过氧化物酶（2-CP）含量降低对拟南芥叶片抗氧化系统的影响。在叶片发育的三个阶段，将叶绿体2-CP含量降低的两个转基因拟南芥突变体系与野生型以及用空载体转化的对照系进行比较。所有植株中的谷胱甘肽含量和氧化还原状态相似，且未观察到谷胱甘肽代谢相关酶转录水平的变化。叶绿体谷胱甘肽过氧化物酶的转录水平远低于2-CP的转录水平，且突变体中胞质和叶绿体谷胱甘肽过氧化物酶均未增加。相反，突变体中叶片抗坏血酸库的氧化程度更高，尽管这种差异随植株年龄增长而减小。类囊体和基质抗坏血酸过氧化物酶，尤其是单脱氢抗坏血酸还原酶的活性增加，这些酶的转录本也增加。未观察到脱氢抗坏血酸还原酶活性的变化，对谷胱甘肽还原酶、过氧化氢酶和超氧化物歧化酶转录丰度的影响轻微或不存在。结果表明，2-CP是叶绿体抗氧化网络的一个组成部分，并与其他防御系统在功能上相互关联。2-CP的抑制可能导致叶片抗坏血酸库氧化状态增加，从而介导其他抗氧化基因表达的增加。
