The challenge of monitoring in planta dynamic changes of NADP(H) and NAD(H) redox states at the subcellular level is considered a major obstacle in plant bioenergetics studies. Here, we introduced two circularly permuted yellow fluorescent protein sensors, iNAP and SoNar, into Arabidopsis thaliana to monitor the dynamic changes in NADPH and the NADH/NAD⁺ ratio. In the light, photosynthesis and photorespiration are linked to the redox states of NAD(P)H and NAD(P) pools in several subcellular compartments connected by the malate-OAA shuttles. We show that the photosynthetic increases in stromal NADPH and NADH/NAD⁺ ratio, but not ATP, disappear when glycine decarboxylation is inhibited. These observations highlight the complex interplay between chloroplasts and mitochondria during photosynthesis and support the suggestions that, under normal conditions, photorespiration supplies a large amount of NADH to mitochondria, exceeding its NADH-dissipating capacity, and the surplus NADH is exported from the mitochondria to the cytosol through the malate-OAA shuttle.

在亚细胞水平上监测植物中NADP(H) 和 NAD(H) 氧化还原状态的动态变化的挑战被认为是植物生物能学研究的主要障碍。在这里，我们将两种循环排列的黄色荧光蛋白传感器 iNAP 和 SoNar 引入拟南芥中，以监测 NADPH 和 NADH/NAD ⁺比率的动态变化。在光照下，光合作用和光呼吸与由苹果酸-OAA 穿梭机连接的几个亚细胞区室中的 NAD(P)H 和 NAD(P) 库的氧化还原状态有关。我们发现，当甘氨酸脱羧被抑制时，基质 NADPH 和 NADH/NAD ⁺比率（而非 ATP）的光合作用增加消失。这些观察结果强调了光合作用过程中叶绿体和线粒体之间复杂的相互作用，并支持了这样的观点：在正常条件下，光呼吸向线粒体提供大量 NADH，超过其 NADH 耗散能力，多余的 NADH 从线粒体输出到线粒体。通过苹果酸-OAA 穿梭机进入细胞质。