State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, 310006, China.
College of Life Science, Dezhou University, Dezhou, 253023, China.
Plant J. 2020 Sep;104(1):44-58. doi: 10.1111/tpj.14904. Epub 2020 Aug 12.
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.
铁氧还蛋白（Fds）在光合作用中通过调节电子向下游酶的分布起着至关重要的作用。在水稻（Oryza sativa L.）基因组中注释了多个 Fd 基因；然而，它们的具体功能尚不清楚。在这里，我们报告了水稻 Fd1 的功能特征。对七种水稻 Fd 蛋白的序列比对、系统发育分析和定量反转录聚合酶链反应（qRT-PCR）分析表明，水稻 Fd1 是一种主要的叶型 Fd。涉及 NADP 和细胞色素 c 的电子转移实验表明，Fd1 可以从光系统 I（PSI）将电子传递给铁氧还蛋白-NADP 还原酶。功能丧失的 fd1 突变体在三叶期表现出黄化和幼苗致死。Fd1 的缺乏会损害光合作用电子传递，从而影响碳同化。外源葡萄糖处理部分恢复了突变体表型，表明 Fd1 在水稻光合作用电子传递中起着重要作用。此外，fd1 突变体中 Fd 依赖性基因的转录水平受到影响，其趋势与 fdc2 植物观察到的相似。总之，这些结果表明 OsFd1 是水稻光合作用电子传递和碳同化中的主要 Fd。
