The Experts below are selected from a list of 173862 Experts worldwide ranked by ideXlab platform
Richard M Amasino - One of the best experts on this subject based on the ideXlab platform.
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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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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.
Ginga Shimakawa - One of the best experts on this subject based on the ideXlab platform.
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The impact of photosynthesis on initiation of leaf Senescence
Physiologia Plantarum, 2019Co-Authors: Anja Krieger-liszkay, Karin Krupinska, Ginga ShimakawaAbstract:Senescence is the last stage of leaf development preceding the death of the organ, and it is important for nutrient remobilization and for feeding sink tissues. There are many reports on leaf Senescence but the mechanisms initiating leaf Senescence are still poorly understood. Leaf Senescence is affected by many environmental factors and seems to vary in different species and even varieties of plants, which makes it difficult to generalize the mechanism. Here, we give an overview on studies reporting about alterations in the composition of the photosynthetic electron transport chain in chloroplasts during Senescence. We hypothesize that alternative electron flow and related generation of the proton motive force required for ATP synthesis become increasingly important during progression of Senescence. We address the generation of reactive oxygen species (ROS) in chloroplasts in the initiation of Senescence, retrograde signaling from the chloroplast to the nucleus and ROS-dependent signaling associated with leaf Senescence. Finally, differences between natural Senescence and dark-induced Senescence are pointed out and a few ideas for increasing crop yields by increasing the chloroplast lifespan are presented. This article is protected by copyright. All rights reserved.
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The impact of photosynthesis on initiation of leaf Senescence
Physiologia Plantarum, 2018Co-Authors: Anja Krieger-liszkay, Karin Krupinska, Ginga ShimakawaAbstract:Senescence is the last stage of leaf development preceding the death of the organ, and it is important for nutrient remobilization and for feeding sink tissues. There are many reports on leaf Senescence but the mechanisms initiating leaf Senescence are still poorly understood. Leaf Senescence is affected by many environmental factors and seems to vary in different species and even varieties of plants, which makes it difficult to generalize the mechanism. Here, we give an overview on studies reporting about alterations in the composition of the photosynthetic electron transport chain in chloroplasts during Senescence. We hypothesize that alternative electron flow and related generation of the proton motive force required for ATP synthesis become increasingly important during progression of Senescence. We address the generation of reactive oxygen species (ROS) in chloroplasts in the initiation of Senescence, retrograde signaling from the chloroplast to the nucleus and ROS-dependent signaling associated with leaf Senescence. Finally, differences between natural Senescence and dark-induced Senescence are 32 pointed out and a few ideas for increasing crop yields by increasing the chloroplast lifespan are presented.
Olivier Toussaint - One of the best experts on this subject based on the ideXlab platform.
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Stress-Induced (Premature) Senescence
Cellular Ageing and Replicative Senescence, 2016Co-Authors: Florence Debacq-chainiaux, Randa Ben Ameur, Emilie Bauwens, Elise Dumortier, Marie Toutfaire, Olivier ToussaintAbstract:Three main roads lead to Senescence: telomere-dependent replicative Senescence, oncogene-induced Senescence and stress-induced (premature) Senescence. This latter type of Senescence appears after exposure of normal, immortalized or transformed cells to stress of chemical or physical nature inducing oxidative stress and/or DNA damage. After these exposures, chronic or acute, single or multiple, stressed cells developed a “Senescence-like” phenotype. This “Senescence-like” phenotype presents several biomarkers of cellular Senescence such as irreversible growth arrest, morphological change, Senescence-associated s-galactosidase (SA-sgal) activity and Senescence-associated secretory phenotype (SASP). However, large-scale studies of transcriptome and proteome of cells in replicative Senescence or in stress-induced Senescence show that although they share similarities, the two phenotypes are not identical. Different signaling pathways involved in the development of stress-induced Senescence are presented as those dependent on TGF-s1, p38MAPK, IGF-R1 and DNA damage. The possible induction of this type of Senescence in vivo and in cancer treatment is discussed.
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Identification of 30 protein species involved in replicative Senescence and stress-induced premature Senescence.
FEBS Letters, 2002Co-Authors: Jean François Dierick, Dario E. Kalume, Frédéric Wenders, Michel Salmon, Marc Dieu, Martine Raes, Peter Roepstorff, Olivier ToussaintAbstract:Exposure of human proliferative cells to subcytotoxic stress triggers stress-induced premature Senescence (SIPS) which is characterized by many biomarkers of replicative Senescence. Proteomic comparison of replicative Senescence and stress-induced premature Senescence indicates that, at the level of protein expression, stress-induced premature Senescence and replicative Senescence are different phenotypes sharing however similarities. In this study, we identified 30 proteins showing changes of expression level specific or common to replicative Senescence and/or stress-induced premature Senescence. These changes affect different cell functions, including energy metabolism, defense systems, maintenance of the redox potential, cell morphology and transduction pathways.
Paul Dijkwel - One of the best experts on this subject based on the ideXlab platform.
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Hormonal regulation of leaf Senescence through integration of developmental and stress signals
Plant Molecular Biology, 2013Co-Authors: Rubina Jibran, Donald Hunter, Paul DijkwelAbstract:Leaf Senescence is a genetically controlled dismantling programme that enables plants to efficiently remobilise nutrients to new growing sinks. It involves substantial metabolic reprogramming whose timing is affected by developmental and environmental signals. Plant hormones have long been known to affect the timing of leaf Senescence, but they also affect plant development and stress responses. It has therefore been difficult to tease apart how the different hormones regulate the onset and progression of leaf Senescence, i.e., whether they directly affect leaf Senescence or affect it indirectly by altering the developmental programme or by altering plants’ response to stress. Here we review research on hormonal regulation of leaf Senescence and propose that hormones affect Senescence through differential responses to developmental and environmental signals. We suggest that leaf Senescence strictly depends on developmental changes, after which Senescence can be induced, depending on the type of hormonal and environmental cues.
Wenying Xu - One of the best experts on this subject based on the ideXlab platform.
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a novel nuclear localized ccch type zinc finger protein osdos is involved in delaying leaf Senescence in rice
Plant Physiology, 2006Co-Authors: Zhaosheng Kong, Meina Li, Wenqiang Yang, Wenying XuAbstract:Leaf Senescence is a developmentally programmed degeneration process, which is fine tuned by a complex regulatory network for plant fitness. However, molecular regulation of leaf Senescence is poorly understood, especially in rice (Oryza sativa), an important staple crop for more than half of the world population. Here, we report a novel nuclear-localized CCCH-type zinc finger protein, Oryza sativa delay of the onset of Senescence (OsDOS), involved in delaying leaf Senescence in rice. The expression of OsDOS was down-regulated during natural leaf Senescence, panicle development, and pollination, although its transcripts were accumulated in various organs. RNAi knockdown of OsDOS caused an accelerated age-dependent leaf Senescence, whereas its overexpression produced a marked delay of leaf Senescence, suggesting that it acts as a negative regulator for leaf Senescence. A genome-wide expression analysis further confirmed its negative regulation for leaf Senescence and revealed that, in particular, the jasmonate (JA) pathway was found to be hyperactive in the OsDOS RNAi transgenic lines but impaired in the OsDOS overexpressing transgenic lines, indicating that this pathway is likely involved in the OsDOS-mediated delaying of leaf Senescence. Furthermore, methyl JA treatments of both seeds and detached leaves from the RNAi and the overexpressing transgenic lines showed hyper- and hyporesponses, respectively, consistent with the negative regulation of the JA pathway by OsDOS. Together, these results indicate that OsDOS is a novel nuclear protein that delays leaf Senescence likely, at least in part, by integrating developmental cues to the JA pathway.
