Ferredoxins (Fds) play a crucial role in photosynthesis by regulating the distribution of electrons to downstream enzymes. Multiple Fd genes have been annotated in the Oryza sativa L. (rice) genome; however, their specific functions are not well understood. Here, we report the functional characterization of rice Fd1. Sequence alignment, phylogenetic analysis of seven rice Fd proteins and quantitative reverse transcription polymerase chain reaction (qRT‐PCR) analysis showed that rice Fd1 is a primary leaf‐type Fd. Electron transfer assays involving NADP⁺ and cytochrome c indicated that Fd1 can donate electrons from photosystem I (PSI) to ferredoxin‐NADP⁺ reductase. Loss‐of‐function fd1 mutants showed chlorosis and seedling lethality at the three‐leaf stage. The deficiency of Fd1 impaired photosynthetic electron transport, which affected carbon assimilation. Exogenous glucose treatment partially restored the mutant phenotype, suggesting that Fd1 plays an important role in photosynthetic electron transport in rice. In addition, the transcript levels of Fd‐dependent genes were affected in fd1 mutants, and the trend was similar to that observed in fdc2 plants. Together, these results suggest that OsFd1 is the primary Fd in photosynthetic electron transport and carbon assimilation in rice.

中文翻译：

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初级叶型铁氧还蛋白1参与水稻的光合作用电子传递和碳同化作用。

铁氧还蛋白（Fds）通过调节电子向下游酶的分布在光合作用中起着至关重要的作用。在水稻基因组中已经注释了多个Fd基因 。但是，它们的具体功能还没有被很好地理解。在这里，我们报告水稻Fd1的功能表征。序列比对，7种水稻Fd蛋白的系统发育分析和定量逆转录聚合酶链反应（qRT-PCR）分析表明，水稻Fd1是主要的叶片型Fd。涉及NADP ⁺和细胞色素 c的电子转移分析表明，Fd1可以将来自光系统I（PSI）的电子捐赠给铁氧还蛋白-NADP ⁺还原酶。功能丧失fd1突变体在三叶期表现出萎黄和幼苗致死力。Fd1的缺乏会损害光合电子的运输，从而影响碳的同化作用。外源葡萄糖处理部分恢复了突变表型，表明Fd1在水稻光合电子传递中起重要作用。此外，Fd的依赖基因转录水平在受灾FD1突变，而且这种趋势相似，在观察FDC2植物。总之，这些结果表明OsFd1是水稻光合作用电子传递和碳同化的主要Fd。