Reports on the effect of nitric oxide (NO) or reactive oxygen species (ROS) on photosynthesis and respiration in leaf tissues are intriguing; therefore, the effects of exogenous addition of sodium nitroprusside (SNP, releases NO) or H2O2 on the photosynthetic O2 evolution and respiratory O2 uptake by mesophyll protoplasts in pea (Pisum sativum) were evaluated in the present study. Low concentrations of SNP or H2O2 were used to minimize nonspecific effects. The effects of NO or H2O2 on respiration and photosynthesis were different. The presence of NO decreased the rate of photosynthesis but caused a marginal stimulation of dark respiration. Conversely, externally administered H2O2 drastically decreased the rate of respiration but only slightly decreased photosynthesis. The PS I activity was more sensitive to NO than PS II. On the other hand, 100 μM H2O2 had no effect on the photochemical reactions of either PS I or PS II. The sensitivity of photosynthesis to antimycin A or SHAM (reflecting the interplay between chloroplasts and mitochondria) was not affected by NO. By contrast, H2O2 markedly decreased the sensitivity of photosynthesis to antimycin A and SHAM. It can be concluded that chloroplasts are the primary targets of NO, while mitochondria are the primary targets of ROS in plant cells. We propose that H2O2 can be an important signal to modulate the crosstalk between chloroplasts and mitochondria.

中文翻译：

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光合作用对一氧化氮敏感，呼吸对过氧化氢敏感：豌豆叶肉原生质体的研究


关于一氧化氮（NO）或活性氧（ROS）对叶组织光合作用和呼吸作用影响的报道很有趣；因此，本研究评估了外源添加硝普钠（SNP，释放NO）或H2O2对豌豆（Pisum sativum）光合放氧和叶肉原生质体呼吸吸氧的影响。使用低浓度的 SNP 或 H2O2 来最大限度地减少非特异性影响。 NO和H2O2对呼吸和光合作用的影响不同。 NO 的存在降低了光合作用的速率，但引起了暗呼吸的边际刺激。相反，外部施用的 H2O2 大大降低了呼吸速率，但仅略微降低了光合作用。 PS I 活性比 PS II 对 NO 更敏感。另一方面，100 μM H2O2 对 PS I 或 PS II 的光化学反应没有影响。光合作用对抗霉素 A 或 SHAM（反映叶绿体和线粒体之间的相互作用）的敏感性不受 NO 的影响。相比之下，H2O2 显着降低了光合作用对抗霉素 A 和 SHAM 的敏感性。由此可见，植物细胞中NO的主要作用靶点是叶绿体，ROS的主要作用靶点是线粒体。我们认为 H2O2 可以成为调节叶绿体和线粒体之间串扰的重要信号。