Multiple strategies to prevent oxidative stress in Arabidopsis plants lacking the malate valve enzyme NADP-malate dehydrogenase.
Multiple strategies to prevent oxidative stress in Arabidopsis plants lacking the malate valve enzyme NADP-malate dehydrogenase.
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DOI：
10.1093/jxb/err386
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发表时间：
2012-02
影响因子：
6.9
通讯作者：
Scheibe R
中科院分区：
文献类型：
--
作者：
Hebbelmann I;Selinski J;Wehmeyer C;Goss T;Voss I;Mulo P;Kangasjärvi S;Aro EM;Oelze ML;Dietz KJ;Nunes-Nesi A;Do PT;Fernie AR;Talla SK;Raghavendra AS;Linke V;Scheibe R
核编码的叶绿体NADP依赖的苹果酸脱氢酶（NADP-MDH）是控制苹果酸阀门的关键酶，允许还原当量的间接输出。拟南芥（Arabidopsis thaliana L.）嘿利用NADP-MDH的T-DNA插入突变体来评估光激活的NADP-MDH在典型C3植物中的作用。令人惊讶的是，即使在短时间内暴露于强光条件下，nadp-mdh敲除突变体在表型上与野生型没有区别。突变体的光合性能和典型的抗氧化系统，如贝克-哈利韦尔-浅田途径，几乎没有受到影响，在响应强光处理。活性氧水平保持较低，表明在突变体中明显不存在氧化应激。进一步的分析揭示了一种新的补偿机制的组合，以保持在nadp-mdh植物在强光条件下的氧化还原稳态，特别是在叶绿体中的NTRC/2-Cys过氧化物酶（Prx）系统的增加。在nadp-mdh基因敲除植株中，光呼吸的叶绿体外组分和脯氨酸水平都有调整的迹象，它们都可以消散多余的还原当量，维持光合作用，防止光抑制。这种代谢的灵活性表明，苹果酸阀与其他NADPH消耗反应，以保持平衡的氧化还原状态在光合作用在强光胁迫下的野生型植物。
The nuclear-encoded chloroplast NADP-dependent malate dehydrogenase (NADP-MDH) is a key enzyme controlling the malate valve, to allow the indirect export of reducing equivalents. Arabidopsis thaliana (L.) Heynh. T-DNA insertion mutants of NADP-MDH were used to assess the role of the light-activated NADP-MDH in a typical C3 plant. Surprisingly, even when exposed to high-light conditions in short days, nadp-mdh knockout mutants were phenotypically indistinguishable from the wild type. The photosynthetic performance and typical antioxidative systems, such as the Beck–Halliwell–Asada pathway, were barely affected in the mutants in response to high-light treatment. The reactive oxygen species levels remained low, indicating the apparent absence of oxidative stress, in the mutants. Further analysis revealed a novel combination of compensatory mechanisms in order to maintain redox homeostasis in the nadp-mdh plants under high-light conditions, particularly an increase in the NTRC/2-Cys peroxiredoxin (Prx) system in chloroplasts. There were indications of adjustments in extra-chloroplastic components of photorespiration and proline levels, which all could dissipate excess reducing equivalents, sustain photosynthesis, and prevent photoinhibition in nadp-mdh knockout plants. Such metabolic flexibility suggests that the malate valve acts in concert with other NADPH-consuming reactions to maintain a balanced redox state during photosynthesis under high-light stress in wild-type plants.
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影响因子：
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