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Authors: Ryo Tachibana, Susumu Abe, Momo Marugami, Ayumi Yamagami, Rino Akema, Takao Ohashi, Kaisei Nishida, Shohei Nosaki, Takuya Miyakawa, Masaru Tanokura, Jong-Myong Kim, Motoaki Seki, Takehito Inaba, Minami Matsui, Kentaro Ifuku, Tetsuo Kushiro, Tadao Asami & Takeshi Nakano
Nature Communications (2023)
Editor's view: The authors identify BPG4, a novel regulator of chloroplast development. BPG4 directly suppresses transcriptional activity of GLK to fine-tune photosynthesis associated nuclear gene expression, and regulates chloroplast development and homeostasis.
Abstract: "Chloroplast development adapts to the environment for performing suitable photosynthesis. Brassinosteroids (BRs), plant steroid hormones, have crucial effects on not only plant growth but also chloroplast development. However, the detailed molecular mechanisms of BR signaling in chloroplast development remain unclear. Here, we identify a regulator of chloroplast development, BPG4, involved in light and BR signaling. BPG4 interacts with GOLDEN2-LIKE (GLK) transcription factors that promote the expression of photosynthesis-associated nuclear genes (PhANGs), and suppresses their activities, thereby causing a decrease in the amounts of chlorophylls and the size of light-harvesting complexes. BPG4 expression is induced by BR deficiency and light, and is regulated by the circadian rhythm. BPG4 deficiency causes increased reactive oxygen species (ROS) generation and damage to photosynthetic activity under excessive high-light conditions. Our findings suggest that BPG4 acts as a chloroplast homeostasis factor by fine-tuning the expression of PhANGs, optimizing chloroplast development, and avoiding ROS generation."
Authors: Zhonghong Ma, Liping Wang, Jingye Fu and Qiang Wang.
Environmental and Experimental Botany (2023)
Highlights • OsDERF8 is identified as the positive regulator of leaf senescence. • Knockout of OsDERF8 resulted in “stay-green” phenotype and higher grain yield per plant. • OsDERF8 is involved in JA signaling and regulates multiple signaling genes.
Abstract: "Plant leaf senescence is regulated by complicated signaling network involving endogenous and environmental factors. Appropriate leaf senescence processing plays important roles in plant growth and stress response and contributes to crop production. The regulatory mechanism of leaf senescence has been widely investigated but still remains elusive. Here we identified the rice transcription factor OsDERF8 as the positive regulator of leaf senescence. Overexpression of OsDERF8 resulted in shortened reproductive stage and earlier leaf senescence, as well as lower grain yield. The knockout lines of OsDERF8 exhibited the “stay-green” phenotype and higher grain yield per plant. Dark induced senescence assays confirmed the function of OsDERF8 in senescence regulation. The leaves of OsDERF8 knockout lines showed less sensitivity to dark treatment with slighter chloroplast damage. OsDERF8 knockout mutants also exhibited less sensitivity to jasmonate (JA) treatment with higher chlorophyll accumulation and less root inhibition. Transcriptomic analysis and promoter-luciferase assays indicated that OsDERF8 regulated multiple senescence related genes, plant hormone related genes and photosynthesis genes. Taken together, OsDERF8 positively regulates rice leaf senescence through JA signaling and might be used for molecular breeding to increase grain yield."
Authors: Fengjun Li, Youxia Shan, Haobin Wang, Guoxiang Jiang, Xiaochun Ding, Hanzhi Liang, Chunlan Wang, Xiangjin Kong, Lihong Xie and Yueming Jiang.
Food Chemistry (2022)
Highlights: • CPPU maintained the cytokinin content and delayed leaf senescence. • BrNAC029 was up-regulated during leaf senescence but suppressed by CPPU treatment. • BrNAC029 served as a transcriptional activator and activated the transcriptions. • A cytokinin analogue-BrNAC029-BrCKX1 regulatory chain regulated leaf senescence.
Abstract: "Both cytokinin and NAC transcription factors were reported to involve in leaf senescence. However, the mechanism of NAC transcription factors how to regulate cytokinin-delayed leaf senescence is still unknown. In this study, application of N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU), a cytokinin analogue, significantly delayed leaf senescence and maintained cytokinin content of Chinese flowering cabbage during storage. Meanwhile, the expression of an NAC transcriptional activator (BrNAC029) was increased but suppressed by CPPU treatment. Furthermore, BrNAC029 activated the expressions of chlorophyll catabolic genes BrPAO and BrSGR2, cytokinin oxidase gene BrCKX1 and senescence maker gene BrSAG113 by binding to their promoters. Additionally, overexpressions of BrNAC029 in tobacco and Arabidopsis accelerated leaf senescence and up-expressed the related genes. Taken together, it was suggested that BrNAC029 may serve as a transcriptional activator to activate the transcriptions of these related genes to eventually accelerate leaf senescence of Chinese flowering cabbage by promoting chlorophyll degradation and reducing endogenous cytokinin level."
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Authors: Hongli Li, Gangshuai Liu and Daqi Fu.
Postharvest Biology and Technology (2023)
Highlights: • Tomato serves as the model plant for studying fruit quality formation. • Fruit quality formation is regulated by a series of transcription factors. • Interactions between transcription factors related to fruit quality.
Abstract: "Tomato serves as the model plant for studying fruit ripening and quality formation including pigment, texture, flavor, aroma and nutrition. The ripening of tomato fruit results from the selective expression of ripening-related genes, which are strictly regulated by transcription factors (TFs), such as RIPENING INHIBITOR (RIN), NON-RIPENING (NOR) and COLORLESS NON-RIPENING (CNR). Understanding the transcriptional network has important biological significance for the fruit ripening regulation, which can help improve fruit quality and commodity value, and improve the utilization of agricultural resources. The molecular mechanism of TF control, a redundant regulatory network, has been extensively studied thanks to advancements in scientific research technologies. Here, we focus on the synergistic or antagonistic regulation of TFs in tomato fruit ripening, including the relationship between TFs and the regulatory patterns of ripening-related target genes, which is supported by sufficient evidence."
Authors: Wei Chen, Yuchen Zheng, Jingyi Wang, Zijing Wang, Zhen Yang, Xiaoyu Chi, Lingyan Dai, Guihua Lu, Yonghua Yang and Bo Sun.
New Phytologist (2023)
Abstract: "The onset of leaf de-greening and senescence is governed by a complex regulatory network including environmental cues and internal factors such as transcription factors (TFs) and phytohormones, in which ethylene (ET) is one key inducer. However, the detailed mechanism of ET signalling for senescence regulation is still largely unknown. Here, we found that the WRKY TF SbWRKY50 from Sorghum bicolor L., a direct target of the key component ETHYLENE INSENSITIVE3 (EIN3) in ET signalling, functioned for leaf senescence repression. The CRISPR/Cas9-edited SbWRKY50 mutant (SbWRKY5O-KO) of sorghum displayed precocious senescent phenotypes, while SbWRKY50 overexpression delayed age-dependent and dark-induced senescence in sorghum. SbWRKY50 negatively regulated chlorophyll degradation through direct binding to the promoters of several chlorophyll catabolic genes. In addition, SbWRKY50 recruited the PRC1 complex through direct interaction with SbBMI1A, to induce H2Aub accumulation on the chlorophyll catabolic genes for epigenetic silencing and thus delayed leaf senescence. Especially, SbWRKY50 can suppress early steps of chlorophyll catabolic pathway via directly repressing SbNYC1 (NON-YELLOW COLORING 1). Other senescence-related hormones could also influence leaf senescence through repression of SbWRKY50. Hence, our work shows that SbWRKY50 is an essential regulator downstream of ET and SbWRKY50 also responds to other phytohormones for senescence regulation in sorghum."
Authors: Zhiqian Li, Jingwen Li, Xia Ye, Xianbo Zheng, Bin Tan, Jidong Li, Jun Cheng, Wei Wang, Langlang Zhang, Xiaobei Wang and Jiancan Feng.
Scientia Horticulturae (2022)
Highlights • Ethylene plays important role during rachis degreening, expression of VvERF95 can be induced by ethylene. • VvERF95 upregulate VvPAO1 expression by binding to DRE cis-element in its promoter. • Transgenic plants of VvERF95 have lower chlorophyll content and transcript level of VvPAO1 and the other CCGs were increased.
Abstract: "Rachis degreening is one of the main problems during postharvest storage of grape, its regulatory mechanism remains obscure. Here, we found that production of ethylene was increased and chlorophyll content was decreased during rachis degreening of Shine Muscat grape, while the reverse were observed after 1-MCP (1-methylcyclopropene) treatment. The ethylene transcription factor VvERF95 was isolated, and its transcriptional changes were closely correlated with chlorophyll content during rachis browning. The expression of VvERF95 was induced by ethylene and inhibited by 1-MCP. Dual-luciferase, yeast one-hybrid and EMSA assays, as well as motif mutation experiments, indicated that VvERF95 can bind to the promoter of pheophorbide a oxygenase (VvPAO1) and upregulate its transcript levels. Overexpression of VvERF95 in grape lead to chlorophyll degradation in grape leaves, and increases in the transcript levels of VvPAO1 and most genes in the chlorophyll degradation pathway. Collectively, our findings decipher the mechanism of ethylene-enhanced chlorophyll degradation in grape, and will be useful for manipulating chlorophyll accumulation in grape and other plants."
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