Mitochondria are frequently observed in the vicinity of chloroplasts in photosynthesizing cells, and this association is considered necessary for their metabolic interactions. We previously reported that, in leaf palisade cells of Arabidopsis thaliana, mitochondria exhibit blue‐light‐dependent redistribution together with chloroplasts, which conduct accumulation and avoidance responses under the control of blue‐light receptor phototropins. In this study, precise motility analyses by fluorescent microscopy revealed that the individual mitochondria in palisade cells, labeled with green fluorescent protein, exhibit typical stop‐and‐go movement. When exposed to blue light, the velocity of moving mitochondria increased in 30 min, whereas after 4 h, the frequency of stoppage of mitochondrial movement markedly increased. Using different mutant plants, we concluded that the presence of both phototropin1 and phototropin2 is necessary for the early acceleration of mitochondrial movement. On the contrary, the late enhancement of stoppage of mitochondrial movement occurs only in the presence of phototropin2 and only when intact photosynthesis takes place. A plasma‐membrane ghost assay suggested that the stopped mitochondria are firmly adhered to chloroplasts. These results indicate that the physical interaction between mitochondria and chloroplasts is cooperatively mediated by phototropin2‐ and photosynthesis‐dependent signals. The present study might add novel regulatory mechanism for light‐dependent plant organelle interactions.

中文翻译：

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拟南芥叶肉细胞中光蛋白和依赖光合作用的线粒体定位。

经常在光合作用细胞的叶绿体附近观察到线粒体，这种结合被认为是它们的代谢相互作用所必需的。我们之前曾报道过，在拟南芥的叶栅细胞中线粒体与叶绿体一起表现出依赖于蓝光的重新分布，它们在蓝光受体光蛋白的控制下进行积累和避免反应。在这项研究中，通过荧光显微镜进行的精确运动分析表明，栅栏细胞中的单个线粒体被绿色荧光蛋白标记，表现出典型的走走停停的运动。当暴露于蓝光下时，线粒体的运动速度在30分钟内增加，而4小时后，线粒体运动的停止频率显着增加。使用不同的突变植物，我们得出的结论是，phototropin1和phototropin2的存在对于线粒体运动的早期加速是必需的。反之，线粒体运动停止的后期增强仅在存在Phototropin2时发生，并且仅在完整的光合作用发生时发生。血浆膜重影分析表明终止的线粒体牢固地粘附在叶绿体上。这些结果表明线粒体和叶绿体之间的物理相互作用是由光养蛋白2和光合作用依赖性信号协同介导的。本研究可能为光依赖性植物细胞器相互作用增加新的调控机制。这些结果表明线粒体和叶绿体之间的物理相互作用是由光养蛋白2和光合作用依赖性信号协同介导的。本研究可能为光依赖性植物细胞器相互作用增加新的调控机制。这些结果表明线粒体和叶绿体之间的物理相互作用是由光养蛋白2和光合作用依赖性信号协同介导的。本研究可能为光依赖性植物细胞器相互作用增加新的调控机制。