Chlorophyll plays essential roles in photosynthesis and its degradation should be regulated precisely. Chlorophyll b reductase encoded by the gene NYC1 is responsible for catalyzing chlorophyll b degradation and maintaining the stability of photosystems. Although NYC1s have been characterized in many plants, their function in the photosynthetic machinery and the underlying regulatory mechanisms at the whole transcriptome level remain elusive. In this study, the ZjNYC1 gene was cloned from the important warm-season turfgrass Zoysia japonica. Analysis of the subcellular localization revealed that ZjNYC1 was localized in the chloroplasts, and results of the bimolecular fluorescence complementation (BiFC) assay indicated that ZjNYC1 could interact in vivo with the NYC1-like protein, ZjNOL. Overexpression of ZjNYC1 accelerated the degradation of chlorophyll, and promoted senescence with accumulation of ABA and reactive oxygen species (ROS) in Arabidopsis. Expression of ZjNYC1 rescued the stay-green phenotype of the Arabidopsis nyc1 mutant. An integrated analysis of chlorophyll fluorescence test (JIP-test) and RNA-sequencing revealed that ZjNYC1 negatively affected the efficiency of the PSII, PSI, and the intersystem electron transport chain. Furthermore, the Calvin cycle and photorespiration were suppressed, but ABA and ethylene synthesis and signal transduction pathways were activated in the transgenic lines. Collectively, these results demonstrated that ZjNYC1 plays important roles in accelerating chlorophyll degradation and senescence, and caused negative affect on the integrity and functionality of the photosystems.

叶绿素在光合作用中起着至关重要的作用，应精确调节其降解。由NYC1基因编码的叶绿素b还原酶负责催化叶绿素b降解并维持光系统的稳定性。尽管NYC1s已在许多植物中得到表征，但它们在光合作用机制中的功能和整个转录组水平的潜在调节机制仍然难以捉摸。本研究从重要的暖季型草坪草结缕草中克隆了ZjNYC1基因。. 亚细胞定位分析显示 ZjNYC1 定位于叶绿体中，双分子荧光互补 (BiFC) 测定结果表明 ZjNYC1 可以在体内与 NYC1 样蛋白 ZjNOL 相互作用。ZjNYC1 的过表达加速了叶绿素的降解，并通过 ABA 和活性氧 (ROS) 的积累促进了拟南芥的衰老。ZjNYC1 的表达挽救了拟南芥nyc1突变体的保持绿色表型。叶绿素荧光测试（JIP 测试）和 RNA 测序的综合分析表明，ZjNYC1对 PSII、PSI 和系统间电子传输链的效率产生负面影响。此外，卡尔文循环和光呼吸受到抑制，但转基因株系中 ABA 和乙烯的合成和信号转导途径被激活。总的来说，这些结果表明ZjNYC1在加速叶绿素降解和衰老方面起着重要作用，并对光系统的完整性和功能产生负面影响。