Coordinated regulation of photosynthetic and respiratory components is necessary to maintain chloroplast energy balance in varied growth conditions.
Coordinated regulation of photosynthetic and respiratory components is necessary to maintain chloroplast energy balance in varied growth conditions.
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DOI：
10.1093/jxb/erw469
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发表时间：
2017-01-01
影响因子：
6.9
通讯作者：
Vanlerberghe GC
中科院分区：
文献类型：
--
作者：
Dahal K;Martyn GD;Alber NA;Vanlerberghe GC
植物利用交替氧化酶调节光下线粒体呼吸速率，维持叶绿体能量平衡，从而在不同生长条件下优化光合作用。线粒体有一个非能量守恒的替代氧化酶（AOX），建议支持光合作用，可能是通过促进不同生长条件下的能量平衡。为了研究这一点，将野生型（WT）烟草与AOX敲低和过表达株系进行比较。此外，将WT植物中AOX蛋白的量与叶绿体捕光复合物II（LHCB 2）的量进行比较，已知叶绿体捕光复合物II的量响应于叶绿体能量状态。随着生长辐照度的增加，WT叶片保持较高的光呼吸速率（RL），但在WT和转基因株系之间没有观察到RL或光合作用的差异，这表明，在非胁迫条件下，AOX对叶片代谢并不重要，无论生长辐照度如何。然而，在干旱条件下，AOX量成为RL的一个重要决定因素，而RL又是叶绿体能量平衡（测量为光系统II激发压，EP）和光合性能的一个重要决定因素。在野生型中，AOX含量随着生长光照或干旱强度的增加而增加，LHCB 2含量随着生长光照或干旱强度的增加而减少。这些蛋白质量的变化强烈相关，以相反的方式，与生长EP。这表明来自光合电子传递链状态的信号协调控制AOX和LHCB 2的量，然后两者都有助于维持叶绿体能量平衡，特别是在胁迫条件下。
Plants use the alternative oxidase to modulate the rate of mitochondrial respiration in the light, maintaining chloroplast energy balance and hence optimizing photosynthesis under varied growth conditions. Mitochondria have a non-energy-conserving alternative oxidase (AOX) proposed to support photosynthesis, perhaps by promoting energy balance under varying growth conditions. To investigate this, wild-type (WT) Nicotiana tabacum were compared with AOX knockdown and overexpression lines. In addition, the amount of AOX protein in WT plants was compared with that of chloroplast light-harvesting complex II (LHCB2), whose amount is known to respond to chloroplast energy status. With increased growth irradiance, WT leaves maintained higher rates of respiration in the light (RL), but no differences in RL or photosynthesis were seen between the WT and transgenic lines, suggesting that, under non-stress conditions, AOX was not critical for leaf metabolism, regardless of growth irradiance. However, under drought, the AOX amount became an important determinant of RL, which in turn was an important determinant of chloroplast energy balance (measured as photosystem II excitation pressure, EP), and photosynthetic performance. In the WT, the AOX amount increased and the LHCB2 amount decreased with increased growth irradiance or drought severity. These changes in protein amounts correlated strongly, in opposing ways, with growth EP. This suggests that a signal deriving from the photosynthetic electron transport chain status coordinately controls the amounts of AOX and LHCB2, which then both contribute to maintaining chloroplast energy balance, particularly under stress conditions.