Functional characterization of the chlorophyll b reductase gene NYC1 associated with chlorophyll degradation and photosynthesis in Zoysia japonica
Functional characterization of the chlorophyll b reductase gene NYC1 associated with chlorophyll degradation and photosynthesis in Zoysia japonica
复制标题
结缕草叶绿素b还原酶基因NYC1与叶绿素降解和光合作用相关的功能表征
DOI：
10.1016/j.envexpbot.2021.104607
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发表时间：
2021-08-12
影响因子：
5.7
通讯作者：
Wu, Juying
中科院分区：
文献类型：
--
作者：
Teng, Ke;Tan, Penghui;Wu, Juying
叶绿素在光合作用中起着重要作用，其降解应受到精确调控。由NYC 1基因编码的叶绿素B还原酶负责催化叶绿素B的降解并维持光系统的稳定性。尽管NYC1在许多植物中已经被鉴定，但其在光合机制中的功能以及在整个转录组水平上的潜在调控机制仍然是难以捉摸的。本研究从暖季型草坪草结缕草中克隆了ZjNYC1基因。亚细胞定位分析表明ZjNYC1定位在叶绿体中，双分子荧光互补（BiFC）分析结果表明ZjNYC1可以在体内与NYC1样蛋白ZjNOL相互作用。ZjNYC1基因的过表达加速了拟南芥叶绿素的降解，并伴随着阿坝和活性氧（ROS）的积累而促进衰老。ZjNYC1的表达拯救了拟南芥nyc1突变体的绿色表型。叶绿素荧光测试（JIP测试）和RNA测序的综合分析表明，ZjNYC1负面影响PSII，PSI和系统间电子传递链的效率。此外，转基因株系的卡尔文循环和光呼吸受到抑制，但阿坝和乙烯的合成和信号转导途径被激活。这些结果表明ZjNYC1在加速叶绿素降解和衰老中起重要作用，并对光系统的完整性和功能性产生负面影响。
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.