Regulation of mitochondrial NAD pool via NAD+ transporter 2 is essential for matrix NADH homeostasis and ROS production in Arabidopsis
Regulation of mitochondrial NAD pool via NAD+ transporter 2 is essential for matrix NADH homeostasis and ROS production in Arabidopsis
复制标题
通过 NAD( ) 转运蛋白 2 调节线粒体 NAD 池对于拟南芥中基质 NADH 稳态和 ROS 产生至关重要
DOI：
10.1007/s11427-019-9563-y
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发表时间：
2019-08-01
影响因子：
9.1
通讯作者：
Li, Jiayang
中科院分区：
文献类型：
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作者：
Luo, Lilan;He, Yajun;Li, Jiayang
活性氧（ROS）在植物的许多生物过程中起着至关重要的作用，包括发育、对环境刺激的反应和程序性细胞死亡（PCD）。MOSAIC DEATH 1 （MOD1）是拟南芥中一种质体定位的烯酰acp还原酶，对脂肪酸的新生生物合成至关重要。MOD1缺乏会导致苹果酸从叶绿体向线粒体出口增加，以及线粒体产生的ROS和PCD的积累。在这项研究中，我们报道了一种mod1抑制因子som592的鉴定和表征。SOM592编码线粒体定位的NAD+转运蛋白2 （NDT2）。我们发现线粒体NAD库在mod1突变体中升高。在mod1突变体中，som592突变完全抑制线粒体NADH超积累、ROS产生和PCD，表明线粒体NAD积累与ROS/PCD表型之间存在因果关系。我们还表明，在野生型植物中，线粒体NAD（+）摄取参与了对连续光周期的ROS产生的调节。升高替代呼吸途径可以抑制mod1中的ROS积累和PCD，但会导致生长受限。这些发现揭示了拟南芥线粒体通过NADH稳态产生ROS的调节机制，这可能对光周期改变对生长的调节很重要。
Reactive oxygen species (ROS) play a crucial role in numerous biological processes in plants, including development, responses to environmental stimuli, and programmed cell death (PCD). Deficiency in MOSAIC DEATH 1 (MOD1), a plastid-localized enoyl-ACP reductase essential for de novo fatty acid biosynthesis in Arabidopsis thaliana, leads to the increased malate export from chloroplasts to mitochondria, and the subsequent accumulation of mitochondria-generated ROS and PCD. In this study, we report the identification and characterization of a mod1 suppressor, som592. SOM592 encodes mitochondrion-localized NAD+ transporter 2 (NDT2). We show that the mitochondrial NAD pool is elevated in the mod1 mutant. The som592 mutation fully suppressed mitochondrial NADH hyper-accumulation, ROS production, and PCD in the mod1 mutant, indicating a causal relationship between mitochondrial NAD accumulation and ROS/PCD phenotypes. We also show that in wild-type plants, the mitochondrial NAD(+) uptake is involved in the regulation of ROS production in response to continuous photoperiod. Elevation of the alternative respiration pathway can suppress ROS accumulation and PCD in mod1, but leads to growth restriction. These findings uncover a regulatory mechanism for mitochondrial ROS production via NADH homeostasis in Arabidopsis thaliana that is likely important for growth regulation in response to altered photoperiod.