Drought and oxidative load in the leaves of C3 plants:: a predominant role for photorespiration?
Drought and oxidative load in the leaves of C3 plants:: a predominant role for photorespiration?
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DOI：
10.1093/aob/mcf096
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发表时间：
2002-06-01
期刊：
影响因子：
4.2
通讯作者：
Foyer, CH
中科院分区：
文献类型：
--
作者：
Noctor, G;Veljovic-Jovanovic, S;Foyer, CH
虽然活性氧在C-3植物叶片的叶绿体和过氧化物酶体中以高速率产生，但大多数注意力集中在胁迫条件如干旱下叶绿体产生增强的潜在破坏性后果上。本文试图提供定量估计的相对贡献的叶绿体电子传递链和乙醇酸氧化酶反应的氧化负荷放在光合叶细胞。光呼吸H2 O2生产率获得光合和光呼吸通量率，来自稳态叶气体交换测量在不同的辐照度和环境CO2。假设10%的光合电子流分配给Mehler反应，光呼吸H2 O2的产生将占在所有测量的辐照度下形成的总H2 O2的约70%。当叶绿体CO2浓度降低时，光呼吸在H2 O2产生中变得更加占主导地位。在较低环境CO2下观察到的通过光呼吸的增加的通量下，Mehler反应必须占总光合电子流的35%以上，以匹配过氧化物酶体H2 O2产生的速率。过氧化物酶体中产生的H2 O2的潜在信号作用被强调，它表明，光呼吸H2 O2可以扰乱叶抗氧化剂池的氧化还原状态。我们讨论了氧化剂，抗氧化剂和氧化还原的变化，导致修改的基因表达，特别是在干旱之间的相互作用，并提请注意光呼吸H2 O2信号和驯化的潜在意义。(C)2002年《植物学年鉴》（Annals of Botany Company）
Although active oxygen species are produced at high rates in both the chloroplasts and peroxisomes of the leaves Of C-3 plants, most attention has focused on the potentially damaging consequences of enhanced chloroplastic production in stress conditions such as drought. This article attempts to provide quantitative estimates of the relative contributions of the chloroplast electron transport chain and the glycolate oxidase reaction to the oxidative load placed on the photosynthetic leaf cell. Rates of photorespiratory H2O2 production were obtained from photosynthetic and photorespiratory flux rates, derived from steady-state leaf gas exchange measurements at varying irradiance and ambient CO2. Assuming a 10 % allocation of photosynthetic electron flow to the Mehler reaction, photorespiratory H2O2 production would account for about 70 % of total H2O2 formed at all irradiances measured. When chloroplastic CO2 concentration rates are decreased, photorespiration becomes even more predominant in H2O2 generation. At the increased flux through photorespiration observed at lower ambient CO2, the Mehler reaction would have to account for more than 35 % of the total photosynthetic electron flow in order to match the rate of peroxisomal H2O2 production. The potential signalling role of H2O2 produced in the peroxisomes is emphasized, and it is demonstrated that photorespiratory H2O2 can perturb the redox states of leaf antioxidant pools. We discuss the interactions between oxidants, antioxidants and redox changes leading to modified gene expression, particularly in relation to drought, and call attention to the potential significance of photorespiratory H2O2 in signalling and acclimation. (C) 2002 Annals of Botany Company.