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Susheng Gan - One of the best experts on this subject based on the ideXlab platform.
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saur36 a small auxin up rna gene is involved in the promotion of Leaf Senescence in arabidopsis
Plant Physiology, 2013Co-Authors: Kai Hou, Susheng GanAbstract:Small Auxin Up RNA genes (SAURs) are early auxin-responsive genes, but whether any of them are involved in Leaf Senescence is not known. Auxin, on the other hand, has been shown to have a role in Leaf Senescence. Some of the external application experiments indicated that auxin can inhibit Leaf Senescence, whereas other experiments indicated that auxin can promote Leaf Senescence. Here, we report the identification and characterization of an Arabidopsis (Arabidopsis thaliana) Leaf Senescence-associated gene named SAG201, which is highly up-regulated during Leaf Senescence and can be induced by 1-naphthaleneacetic acid, a synthetic auxin. It encodes a functionally uncharacterized SAUR that has been annotated as SAUR36. Leaf Senescence in transfer DNA insertion saur36 knockout lines was delayed as revealed by analyses of chlorophyll content, Fv/Fm ratio (a parameter for photosystem II activity), ion leakage, and the expression of Leaf Senescence marker genes. In contrast, transgenic Arabidopsis plants overexpressing SAUR36 (without its 3′ untranslated region [UTR]) displayed an early Leaf Senescence phenotype. However, plants overexpressing SAUR36 with its 3′ UTR were normal and did not exhibit the early-Senescence phenotype. These data suggest that SAUR36 is a positive regulator of Leaf Senescence and may mediate auxin-induced Leaf Senescence and that the 3′ UTR containing a highly conserved downstream destabilizes the SAUR36 transcripts in young leaves.
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an aba regulated and golgi localized protein phosphatase controls water loss during Leaf Senescence in arabidopsis
Plant Journal, 2012Co-Authors: Kewei Zhang, Yanyan Zhang, Xiuying Xia, Susheng GanAbstract:It is known that a senescing Leaf loses water faster than a non-senescing Leaf and that ABA has an important role in promoting Leaf Senescence. However, questions such as why water loss is faster, how water loss is regulated, and how ABA functions in Leaf Senescence are not well understood. Here we report on the identification and functional analysis of a Leaf Senescence associated gene called SAG113. The RNA blot and GUS reporter analyses all show that SAG113 is expressed in senescing leaves and is induced by ABA in Arabidopsis. The SAG113 expression levels are significantly reduced in aba2 and abi4 mutants. A GFP fusion protein analysis revealed that SAG113 protein is localized in the Golgi apparatus. SAG113 encodes a protein phosphatase that belongs to the PP2C family and is able to functionally complement a yeast PP2C-deficient mutant TM126 (ptc1Δ). Leaf Senescence is delayed in the SAG113 knockout mutant compared with that in the wild type, stomatal movement in the senescing leaves of SAG113 knockouts is more sensitive to ABA than that of the wild type, and the rate of water loss in senescing leaves of SAG113 knockouts is significantly reduced. In contrast, inducible over-expression of SAG113 results in a lower sensitivity of stomatal movement to ABA treatment, more rapid water loss, and precocious Leaf Senescence. No other aspects of growth and development, including seed germination, were observed. These findings suggest that SAG113, a negative regulator of ABA signal transduction, is specifically involved in the control of water loss during Leaf Senescence.
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an arabidopsis mitogen activated protein kinase cascade mkk9 mpk6 plays a role in Leaf Senescence
Plant Physiology, 2009Co-Authors: Chunjiang Zhou, Yongfeng Guo, Zhaohui Cai, Susheng GanAbstract:Leaf Senescence is a developmentally programmed cell death process that constitutes the final step of Leaf development, and it can be regulated by multiple environmental cues and endogenous signals. The mitogen-activated protein kinase (MAPK) cascades play diverse roles in intracellular and extracellular signaling in plants. Roles of the MAPK signaling module in Leaf Senescence are unknown. Here, a MAPK cascade involving MKK9-MPK6 is shown to play an important role in regulating Leaf Senescence in Arabidopsis (Arabidopsis thaliana). Both MKK9 and MPK6 possess kinase activities, with MPK6 an immediate target of MKK9, as revealed by in vitro, in vivo, and in planta assays. The constitutive and inducible overexpression of MKK9 causes premature Senescence in leaves and in whole Arabidopsis plants. The premature Senescence phenotype is suppressed when MKK9 is overexpressed in the mpk6 null background. When either MKK9 or MPK6 is knocked out, Leaf Senescence is delayed.
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atnap a nac family transcription factor has an important role in Leaf Senescence
Plant Journal, 2006Co-Authors: Yongfeng Guo, Susheng GanAbstract:Leaf Senescence is a unique developmental process that is characterized by massive programmed cell death and nutrient recycling. The underlying molecular regulatory mechanisms are not well understood. Here we report the functional analysis of AtNAP, a gene encoding a NAC family transcription factor. Expression of this gene is closely associated with the Senescence process of Arabidopsis rosette leaves. Leaf Senescence in two T-DNA insertion lines of this gene is significantly delayed. The T-DNA knockout plants are otherwise normal. The mutant phenotype can be restored to wild-type by the intact AtNAP, as well as by its homologs in rice and kidney bean plants that are also upregulated during Leaf Senescence. Furthermore, inducible overexpression of AtNAP causes precocious Senescence. These data strongly suggest that AtNAP and its homologs play an important role in Leaf Senescence in Arabidopsis and possibly in other plant species.
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Leaf Senescence signals execution and regulation
Current Topics in Developmental Biology, 2005Co-Authors: Yongfeng Guo, Susheng GanAbstract:Leaf Senescence is a type of postmitotic Senescence. The onset and progression of Leaf Senescence are controlled by an array of external and internal factors including age, levels of plant hormones/growth regulators, and reproductive growth. Many environmental stresses and biological insults such as extreme temperature, drought, nutrient deficiency, insufficient light/shadow/darkness, and pathogen infection can induce Senescence. Perception of signals often leads to changes in gene expression, and the upregulation of thousands of Senescence-associated genes (SAGs) causes the Senescence syndrome: decline in photosynthesis, degradation of macromolecules, mobilization of nutrients, and ultimate cell death. Identification and analysis of SAGs, especially genome-scale investigations on gene expression during Leaf Senescence, make it possible to decipher the molecular mechanisms of signal perception, execution, and regulation of the Leaf Senescence process. Biochemical and metabolic changes during Senescence have been elucidated, and potential components in signal transduction such as receptor-like kinases and MAP kinase cascade have been identified. Studies on some master regulators such as WRKY transcription factors and the Senescence-responsive cis element of the Senescence-specific SAG12 have shed some light on transcriptional regulation of Leaf Senescence.
Hongwei Guo - One of the best experts on this subject based on the ideXlab platform.
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genetic network between Leaf Senescence and plant immunity crucial regulatory nodes and new insights
Plants (Basel Switzerland), 2020Co-Authors: Yi Zhang, Houling Wang, Hongwei GuoAbstract:Leaf Senescence is an essential physiological process that is accompanied by the remobilization of nutrients from senescent leaves to young leaves or other developing organs. Although Leaf Senescence is a genetically programmed process, it can be induced by a wide variety of biotic and abiotic factors. Accumulating studies demonstrate that Senescence-associated transcription factors (Sen-TFs) play key regulatory roles in controlling the initiation and progression of Leaf Senescence process. Interestingly, recent functional studies also reveal that a number of Sen-TFs function as positive or negative regulators of plant immunity. Moreover, the plant hormone salicylic acid (SA) and reactive oxygen species (ROS) have been demonstrated to be key signaling molecules in regulating Leaf Senescence and plant immunity, suggesting that these two processes share similar or common regulatory networks. However, the interactions between Leaf Senescence and plant immunity did not attract sufficient attention to plant scientists. Here, we review the regulatory roles of SA and ROS in biotic and abiotic stresses, as well as the cross-talks between SA/ROS and other hormones in Leaf Senescence and plant immunity, summarize the transcriptional controls of Sen-TFs on SA and ROS signal pathways, and analyze the cross-regulation between Senescence and immunity through a broad literature survey. In-depth understandings of the cross-regulatory mechanisms between Leaf Senescence and plant immunity will facilitate the cultivation of high-yield and disease-resistant crops through a molecular breeding strategy.
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lsd 3 0 a comprehensive resource for the Leaf Senescence research community
Nucleic Acids Research, 2020Co-Authors: Yi Zhang, Houling Wang, Yang Zhang, Dong Zou, Yi Zhao, Xinli Xia, Jingchu Luo, Hongwei GuoAbstract:The Leaf Senescence database (LSD) is a comprehensive resource of Senescence-associated genes (SAGs) and their corresponding mutants. Through manual curation and extensive annotation, we updated the LSD to a new version LSD 3.0, which contains 5853 genes and 617 mutants from 68 species. To provide sustainable and reliable services for the plant research community, LSD 3.0 (https://bigd.big.ac.cn/lsd/) has been moved to and maintained by the National Genomics Data Center at Beijing Institute of Genomics, Chinese Academy of Sciences. In the current release, we added some new features: (i) Transcriptome data of Leaf Senescence in poplar were integrated; (ii) Leaf Senescence-associated transcriptome data information in Arabidopsis, rice and soybean were included; (iii) Senescence-differentially expressed small RNAs (Sen-smRNA) in Arabidopsis were identified; (iv) Interaction pairs between Sen-smRNAs and Senescence-associated transcription factors (Sen-TF) were established; (v) Senescence phenotypes of 90 natural accessions (ecotypes) and 42 images of ecotypes in Arabidopsis were incorporated; (vi) Mutant seed information of SAGs in rice obtained from Kitbase was integrated; (vii) New options of search engines for ecotypes and transcriptome data were implemented. Together, the updated database bears great utility to continue to provide users with useful resources for studies of Leaf Senescence.
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ethylene insensitive3 is a Senescence associated gene that accelerates age dependent Leaf Senescence by directly repressing mir164 transcription in arabidopsis
The Plant Cell, 2013Co-Authors: Hongwei Guo, Jinying Peng, Xing WenAbstract:Numerous endogenous and environmental signals regulate the intricate and highly orchestrated process of plant Senescence. Ethylene is a well-known inducer of Senescence, including fruit ripening and flower and Leaf Senescence. However, the underlying molecular mechanism of ethylene-induced Leaf Senescence remains to be elucidated. Here, we examine ETHYLENE-INSENSITIVE3 (EIN3), a key transcription factor in ethylene signaling, and find that EIN3 is a functional Senescence-associated gene. Constitutive overexpression or temporary activation of EIN3 is sufficient to accelerate Leaf Senescence symptoms. Conversely, loss of EIN3 and EIN3-Like1 (its close homolog) function leads to a delay in age-dependent and ethylene-, jasmonic acid-, or dark-induced Leaf Senescence. We further found that EIN3 acts downstream of ORESARA2 (ORE2)/ORE3/EIN2 to repress miR164 transcription and upregulate the transcript levels of ORE1/NAC2, a target gene of miR164. EIN3 directly binds to the promoters of microRNA164 (miR164), and this binding activity progressively increases during Leaf ageing. Genetic analysis revealed that overexpression of miR164 or knockout of ORE1/NAC2 represses EIN3-induced early-Senescence phenotypes. Collectively, our study defines a continuation of the signaling pathway involving EIN2-EIN3-miR164-NAC2 in regulating Leaf Senescence and provides a mechanistic insight into how ethylene promotes the progression of Leaf Senescence in Arabidopsis thaliana.
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gene network analysis and functional studies of Senescence associated genes reveal novel regulators of arabidopsis Leaf Senescence
Journal of Integrative Plant Biology, 2012Co-Authors: Jinying Peng, Xing Wen, Hongwei GuoAbstract:Plant Leaf Senescence has been recognized as the last phase of plant development, a highly ordered process regulated by genes known as Senescence associated genes (SAGs). However, the function of most of SAGs in regulating Leaf Senescence as well as regulators of those functionally known SAGs are still unclear. We have previously developed a curated database of genes potentially associated with Leaf Senescence, the Leaf Senescence Database (LSD). In this study, we built gene networks to identify common regulators of Leaf Senescence in Arabidopsis thaliana using promoting or delaying Senescence genes in LSD. Our results demonstrated that plant hormones cytokinin, auxin, nitric oxide as well as small molecules, such as Ca(2+), delay Leaf Senescence. By contrast, ethylene, ABA, SA and JA as well as small molecules, such as oxygen, promote Leaf Senescence, altogether supporting the idea that phytohormones play a critical role in regulating Leaf Senescence. Functional analysis of candidate SAGs in LSD revealed that a WRKY transcription factor WRKY75 and a Cys2/His2-type transcription factor AZF2 are positive regulators of Leaf Senescence and loss-of-function of WRKY75 or AZF2 delayed Leaf Senescence. We also found that silencing of a protein phosphatase, AtMKP2, promoted early Senescence. Collectively, LSD can serve as a comprehensive resource for systematic study of the molecular mechanism of Leaf Senescence as well as offer candidate genes for functional analyses.
Richard M Amasino - One of the best experts on this subject based on the ideXlab platform.
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nutrients mobilized from leaves of arabidopsis thaliana during Leaf Senescence
Journal of Plant Physiology, 2001Co-Authors: E Himelblau, Richard M AmasinoAbstract:Summary During Leaf Senescence nutrients are mobilized to seeds, storage organs or new vegetative growth. Here we determine the changes in the levels of various nutrients during Leaf Senescence in Arabidopsis thaliana . Levels of C, Cr, Cu, Fe, K, Mo, N, P, S and Zn drop by greater than 40 percnt; during Senescence indicating that these nutrients are mobilized from senescing leaves. Thus, for some elements, Arabidopsis is an effective model for the study of mobilization during Senescence. Mutations in two Senescence-induced genes involved in copper transport, COPPER CHAPERONE and RESPONSIVE-TO-ANTAGONIST1 were identified. Nutrient mobilization is not affected in the cch-1 mutant indicating that the CCH gene product does not play a role in this process or that a gene with redundant function exists. It was not possible to analyze nutrient mobilization in the ran1-4 mutant due to the numerous pleiotropic effects of this mutation. Nevertheless, these experiments provide an approach for future studies of the molecular genetics of nutrient mobilization.
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Molecular aspects of Leaf Senescence.
Trends in plant science, 2000Co-Authors: B. F. Quirino, Y S Noh, E Himelblau, Richard M AmasinoAbstract:Senescence is the last stage of Leaf development and one type of programmed cell death that occurs in plants. The relationships among Senescence programs that are induced by a variety of factors have been addressed at a molecular level in recent studies. Furthermore, an overlap between the pathogen-response and Senescence programs is beginning to be characterized. The complexity of the Senescence program is also evident in studies of Senescence-specific gene regulation and the role of photosynthesis and plant hormones in Senescence regulation. New molecular-genetic approaches are expected to be useful in unraveling the molecular mechanisms of the Leaf Senescence program.
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diverse range of gene activity during arabidopsis thaliana Leaf Senescence includes pathogen independent induction of defense related genes
Plant Molecular Biology, 1999Co-Authors: Betania F Quirino, Jennifer Normanly, Richard M AmasinoAbstract:To determine the range of gene activities associated with Leaf Senescence, we have identified genes that show preferential transcript accumulation during this developmental stage. The mRNA levels of a diverse array of gene products increases during Leaf Senescence, including a protease, a ribosomal protein, two cinnamyl alcohol dehydrogenases, a nitrilase and glyoxalase II. Two of the genes identified are known to be pathogen-induced. The Senescence specificity of each gene was determined by characterization of transcript accumulation during Leaf development and in different tissues. The increased expression of nitrilase in senescent leaves is paralleled by an increase in free indole-3-acetic acid (IAA) levels. Additionally, we have demonstrated that the induction of defense-related genes during Leaf Senescence is pathogen-independent and that salicylic acid accumulation is not essential for this induction. Our data indicate that the induction of certain genes involved in plant defense responses is a component of the Leaf Senescence program.
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Making sense of Senescence : Molecular genetic regulation and manipulation of Leaf Senescence
Plant Physiology, 1997Co-Authors: Susheng Gan, Richard M AmasinoAbstract:Leaf Senescence is the final stage of Leaf development. In forests of deciduous trees, the autumn colors that develop during Leaf Senescence are of great aesthetic value. This process is also of great practical value because during Leaf Senescence, nutrients are recycled to other parts of the plant. For example, nitrogen from leaves of deciduous trees is used for the synthesis of storage proteins in stems that will support growth during the following spring (Clausen and Apel, 1991). However, in an agricultural setting, Leaf Senescence may limit yield in certain crops. Senescence also contributes to the postharvest loss of vegetable crops. Therefore, studying Leaf Senescence will not only contribute to our knowledge about this fundamental developmental process, but may also lead to ways of manipulating Senescence for agricultural applications. There have been many physiological, biochemical, and molecular studies of Leaf Senescence. These studies show that during Senescence Leaf cells undergo highly coordinated changes in cell structure, metabolism, and gene expression. The earliest and most significant change in cell structure is the breakdown of the chloroplast, the organelle that contains up to 70% of the Leaf protein. Metabolically, carbon assimilation (photosynthesis) is replaced by catabolism of chlorophyll and macromolecules such as proteins, membrane lipids, and RNA so that some of the released nutrients can be recycled. At the molecular level, these changes are accompanied by, or perhaps driven by, changes in gene expression. In this Update, we summarize physiological and biochemical studies that have contributed to the present understanding of Leaf Senescence, then we discuss current molecular investigations into the regulatory mechanism(s) underlying Leaf Senescence, and, finally, we review some molecular approaches toward the manipulation of Leaf Senescence.
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molecular analysis of natural Leaf Senescence in arabidopsis thaliana
Physiologia Plantarum, 1994Co-Authors: Karin N Lohman, Susheng Gan, Manorama C John, Richard M AmasinoAbstract:We have analyzed macromolecular changes that are associated with natural Leaf Senescence in Arabidopsis thaliana. The loss of chlorophyll that is characteristic of Leaf Senescence is accompanied by a specific pattern of decline of total RNA and protein levels. We have constructed two cDNA libraries representing mRNAs from Arabidopsis leaves at different Senescence stages. Six cDNA clones corresponding to mRNAs that substantially increase in abundance during Senescence were isolated. The levels of these mRNAs remain elevated into the late stages of Senescence when most of the chlorophyll and protein of the Leaf has been degraded. Sis cDNA clones that correspond to mRNAs that exhibit contrasting behavior were also identified: the levels of these mRNAs decrease to undetectable levels during Senescence. The changes in the levels of these specific mRNAs during the course of Senescence are presented. The results indicate that major changes in gene expression occur in Arabidopsis leaves during the process of Senescence.
Sergi Munnebosch - One of the best experts on this subject based on the ideXlab platform.
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photo oxidative stress markers as a measure of abiotic stress induced Leaf Senescence advantages and limitations
Journal of Experimental Botany, 2014Co-Authors: Marta Pintomarijuan, Sergi MunneboschAbstract:Inside chloroplasts, several abiotic stresses (including drought, high light, salinity, or extreme temperatures) induce a reduction in CO2 assimilation rates with a consequent increase in reactive oxygen species (ROS) production, ultimately leading to Leaf Senescence and yield loss. Photo-oxidation processes should therefore be mitigated to prevent Leaf Senescence, and plants have evolved several mechanisms to either prevent the formation of ROS or eliminate them. Technology evolution during the past decade has brought faster and more precise methodologies to quantify ROS production effects and damage, and the capacities of plants to withstand oxidative stress. Nevertheless, it is very difficult to disentangle photo-oxidative processes that bring Leaf defence and acclimation, from those leading to Leaf Senescence (and consequently death). It is important to avoid the mistake of discussing results on Leaf extracts as being equivalent to chloroplast extracts without taking into account that other organelles, such as peroxisomes, mitochondria, or the apoplast also significantly contribute to the overall ROS production within the cell. Another important aspect is that studies on abiotic stress-induced Leaf Senescence in crops do not always include a time-course evolution of studied processes, which limits our knowledge about what photo-oxidative stress processes are required to irreversibly induce the Senescence programme. This review will summarize the current technologies used to evaluate the extent of photo-oxidative stress in plants, and discuss their advantages and limitations in characterizing abiotic stress-induced Leaf Senescence in crops.
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photo and antioxidant protection and salicylic acid accumulation during post anthesis Leaf Senescence in salvia lanigera grown under mediterranean climate
Physiologia Plantarum, 2007Co-Authors: Maria Elizabeth Abreu, Sergi MunneboschAbstract:: Post-anthesis Leaf Senescence is a key developmental process in the life of plants as it is the time during which material built up by the plant during its growth phase is mobilized into reproductive tissues. Here we aimed to study the extent of photo- and antioxidant protection and salicylic acid (SA) accumulation during post-anthesis Leaf Senescence in a perennial plant, Salvia lanigera Poir. grown under Mediterranean field conditions. SA levels increased sharply (up to 2.7-fold) during early stages of Leaf Senescence until fruit and seed formation occurred (i.e. 4 weeks after anthesis). Later on, SA levels kept at constant high levels until Leaf abscission occurred (i.e. 7 weeks after anthesis). Reductions in chlorophyll and carotenoid (lutein, violaxanthin and beta-carotene) levels occurred progressively during Leaf Senescence. In contrast, xanthophyll cycle de-epoxidation increased during early stages of Leaf Senescence and remained constant later, similar to SA accumulation. Indeed, xanthophyll cycle de-epoxidation strongly positively correlated with SA levels (r(2) = 0.92). The maximum efficiency of PSII (F(v)/F(m) ratio) kept around 0.80 throughout the experiment, except during the latest stage of Leaf Senescence (i.e. after fruit and seed formation), when this ratio decreased to 0.72, thus indicating damage to PSII. It is concluded that endogenous SA levels increase sharply during early stages of post-anthesis Leaf Senescence and concomitantly with activation of photoprotection mechanisms, such as xanthophyll cycle-dependent excess energy dissipation, thus avoiding damage to PSII until fruit and seed formation have been accomplished.
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photo and antioxidative protection during summer Leaf Senescence in pistacia lentiscus l grown under mediterranean field conditions
Annals of Botany, 2003Co-Authors: Sergi Munnebosch, Josep PenuelasAbstract:Summer Leaf Senescence in Pistacia lentiscus L. plants serves to remobilize nutrients from the oldest leaves to the youngest ones, and therefore contributes to plant survival during the adverse climatic conditions typical of Mediterranean summers, i.e. water deficit superimposed on high solar radiation and high temperatures. To evaluate the extent of photo- and antioxidative protection during Leaf Senescence of this species, changes in carotenoids, including xanthophyll cycle pigments, and in the levels of ascorbate and α-tocopherol were measured prior to and during summer Leaf Senescence in 3-year-old plants grown under Mediterranean field conditions. Although a chlorophyll loss of approx. 20 % was observed during the first stages of Leaf Senescence, no damage to the photosynthetic apparatus occurred as indicated by constant maximum efficiencies of photosystem II photochemistry. During this period the de-epoxidation state of the xanthophyll cycle, and lutein, neoxanthin and ascorbate levels were kept constant. At the same time β-carotene and α-tocopherol levels increased by approx. 9 and 70 %, respectively, presumably conferring photo- and antioxidative protection to the photosynthetic apparatus. By contrast, during the later stages of Leaf Senescence, characterized by severe chlorophyll loss, carotenoids were moderately degraded (neoxanthin by approx. 20 %, and both lutein and β-carotene by approx. 35 %), ascorbate decreased by approx. 80 % and α-tocopherol was not detected in senescing leaves. This study demonstrates that mechanisms of photo- and antioxidative protection may play a major role in maintaining chloroplast function during the first stages of Leaf Senescence, while antioxidant defences are lost during the latest stages of Senescence.
Hong Gil Nam - One of the best experts on this subject based on the ideXlab platform.
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Leaf Senescence systems and dynamics aspects
Annual Review of Plant Biology, 2019Co-Authors: Hye Ryun Woo, Pyung Ok Lim, Hyo Jung Kim, Hong Gil NamAbstract:Leaf Senescence is an important developmental process involving orderly disassembly of macromolecules for relocating nutrients from leaves to other organs and is critical for plants' fitness. Leaf Senescence is the response of an intricate integration of various environmental signals and Leaf age information and involves a complex and highly regulated process with the coordinated actions of multiple pathways. Impressive progress has been made in understanding how Senescence signals are perceived and processed, how the orderly degeneration process is regulated, how the Senescence program interacts with environmental signals, and how Senescence regulatory genes contribute to plant productivity and fitness. Employment of systems approaches using omics-based technologies and characterization of key regulators have been fruitful in providing newly emerging regulatory mechanisms. This review mainly discusses recent advances in systems understanding of Leaf Senescence from a molecular network dynamics perspective. Genetic strategies for improving the productivity and quality of crops are also described.
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regulatory network of nac transcription factors in Leaf Senescence
Current Opinion in Plant Biology, 2016Co-Authors: Hyo Jung Kim, Hong Gil Nam, Pyung Ok LimAbstract:Leaf Senescence is finely tuned by many regulatory factors such as NAC (NAM/ATAF/CUC) transcription factors (TFs). NACs comprise one of the largest families of TFs in plants, many of which are differentially regulated during Leaf Senescence and play a major role in Leaf Senescence. Recent studies advanced our understanding on the structural and functional features of NAC TFs including target binding specificities of the N-terminal DNA binding domain and dynamic interaction of the C-terminal intrinsically disordered domain with other proteins. NAC TFs control other NACs and also interact with NACs or other TFs to fine-tune the expression of target genes. These studies clearly demonstrated the highly complex characteristics of NAC regulatory networks, which are dynamically regulated temporally and spatially and effectively integrate multiple developmental and environmental signals.
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Toward Systems Understanding of Leaf Senescence: An Integrated Multi-Omics Perspective on Leaf Senescence Research
Molecular Plant, 2016Co-Authors: Jeongsik Kim, Hye Ryun Woo, Hong Gil NamAbstract:Leaf Senescence is a complex but tightly regulated developmental process involving a coordinated sequence of multiple molecular events, which ultimately leads to death of the Leaf. Efforts to understand the mechanistic principles underlying Leaf Senescence have been largely made by transcriptomic, proteomic, and metabolomic studies over the past decade. This review focuses on recent milestones in Leaf Senescence research obtained using multi-omics technologies, as well as future endeavors toward systems understanding of Leaf Senescence processes. In particular, we discuss recent advances in understanding molecular events during Leaf Senescence through genome-wide transcriptome analyses in Arabidopsis. We also describe comparative transcriptome analyses used to unveil the commonality and diversity of regulatory mechanisms governing Leaf Senescence in the plant kingdom. Finally, we provide current illustrations of epigenomic, proteomic, and metabolomic landscapes of Leaf Senescence. We envisage that integration of multi-omics Leaf Senescence data will enable us to address unresolved questions regarding Leaf Senescence, including determining the molecular principles that coordinate concurrent and ordered changes in biological events during Leaf Senescence.
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Molecular genetics of Leaf Senescence in Arabidopsis
Trends in Plant Science, 2003Co-Authors: Pyung Ok Lim, Hye Ryun Woo, Hong Gil NamAbstract:Leaf Senescence is a developmentally programmed degeneration process that constitutes the final step of Leaf development and is controlled by multiple developmental and environmental signals. In addition to the information obtained from other plants, Arabidopsis has, as a model system, contributed to our understanding of this complex phenomenon in molecular genetic terms. Recent discoveries have identified several genetic mutants and potential regulatory components in Arabidopsis. Identifying further mutants that exploit novel biological resources, screening Scheme and a global functional analysis of Senescence-associated genes in Arabidopsis should increase our understanding of the complex regulatory networks.
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identification of three genetic loci controlling Leaf Senescence in arabidopsis thaliana
Plant Journal, 1997Co-Authors: Joonhyun Park, Gyu In Lee, Kyung Hee Paek, Soon Ki Park, Hong Gil NamAbstract:Four mutants that show the delayed Leaf Senescence phenotype were isolated from Arabidopsis thaliana. Genetic analyses revealed that they are all monogenic recessive mutations and fall into three complementation groups, identifying three genetic loci controlling Leaf Senescence in Arabidopsis. Mutations in these loci cause delay in all Senescence parameters examined, including chlorophyll content, photochemical efficiency of photosystem II, relative amount of the large subunit of Rubisco, and RNase and peroxidase activity. Delay of the Senescence symptoms was observed during both age-dependent in planta Senescence and dark-induced artificial Senescence in all of the mutant plants. The results indicate that the three genes defined by the mutations are key genetic elements controlling functional Leaf Senescence and provide decisive genetic evidence that Leaf Senescence is a genetically programmed phenomenon controlled by several monogenic loci in Arabidopsis. The results further suggest that the three genes function at a common step of age-dependent and dark-induced Senescence processes. It is further shown that one of the mutations is allelic to ein2-1, an ethylene-insensitive mutation, confirming the role of ethylene signal transduction pathway in Leaf Senescence of Arabidopsis.