Epigenetic control of plant senescence and linked processes
TL;DR: The review outlines the concept of epigenetic control of interconnected regulatory pathways steering stress responses and plant development and summarizes recent findings on global alterations in chromatin structure, histone and DNA modifications, and ATP-dependent chromatin remodelling during plant senescence and linked processes.
Abstract: Senescence processes are part of the plant developmental programme. They involve reprogramming of gene expression and are under the control of a complex regulatory network closely linked to other developmental and stressresponsive pathways. Recent evidence indicates that leaf senescence is regulated via epigenetic mechanisms. In the present review, the epigenetic control of plant senescence is discussed in the broader context of environmentsensitive plant development. The review outlines the concept of epigenetic control of interconnected regulatory pathways steering stress responses and plant development. Besides giving an overview of techniques used in the field, it summarizes recent findings on global alterations in chromatin structure, histone and DNA modifications, and ATPdependent chromatin remodelling during plant senescence and linked processes.
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01 Jan 2017
TL;DR: This chapter covers an overview on plant senescence, particularly focussed on thesenescence of the leaf, including the most recent findings about features, signalling, regulation and pathways involved in this natural or induced process.
Abstract: Plant senescence is a complex physiological process consequence either of the natural lifespan or externally induced by abiotic and biotic factors. It comprises a coordinated sequence of molecular and biochemical events, phenotypically illustrated by changes in plant colour. Senescence is associated with alterations in chlorophyll and pigment content, reduction of photosynthesis, hydrolysis of macromolecules to produce more simple compounds and dismantling of cell organelles, to finally produce cell death. At the end, relocation of nutrients from the senescent tissues towards sink organs or growing tissues takes place to complete a recycling process. Consequently, the major part of the nitrogen is released as ammonium after being re-assimilated into amino acids to be exported via the phloem to the developing grains, fruits and tubers. During senescence, the reprograming of thousands of genes is triggered in response to specific senescence-promoting factors under a restricted regulatory control. The actual high-throughput omics technologies have led to the generation of integrative information, which has been used to understand the physiological changes during the onset and progression of senescence. This chapter covers an overview on plant senescence, particularly focussed on the senescence of the leaf, including the most recent findings about features, signalling, regulation and pathways involved in this natural or induced process.
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TL;DR: This review provides an overview of the known epigenetic regulation of plant senescence, which has mostly been studied in the form of leaf senescENCE, and it also covers what has been reported about whole-plant senescences.
Abstract: Senescence is a major developmental transition in plants that requires a massive reprogramming of gene expression and includes various layers of regulations. Senescence is either an age-dependent or a stress-induced process, and is under the control of complex regulatory networks that interact with each other. It has been shown that besides genetic reprogramming, which is an important aspect of plant senescence, transcription factors and higher-level mechanisms, such as epigenetic and small RNA-mediated regulators, are also key factors of senescence-related genes. Epigenetic mechanisms are an important layer of this multilevel regulatory system that change the activity of transcription factors (TFs) and play an important role in modulating the expression of senescence-related gene. They include chromatin remodeling, DNA methylation, histone modification, and the RNA-mediated control of transcription factors and genes. This review provides an overview of the known epigenetic regulation of plant senescence, which has mostly been studied in the form of leaf senescence, and it also covers what has been reported about whole-plant senescence.
7 citations
Dissertation•
04 Feb 2016
TL;DR: El proceso in vitro embriogenica es de gran interes basico y aplicado en biotecnologia y mejora vegetal para la obtencion rapida de nuevas variedades, sin embargo aun tiene importantes limitaciones en su explotacion por su baja eficiencia en muchas especies ofinteres economico.
Abstract: La embriogenesis de microsporas es un proceso in vitro en el que la microspora o polen inmaduro, mediante la aplicacion de un tratamiento de estres se reprograma y abandona su ruta de desarrollo gametofitico para iniciar la ruta embriogenica, dando lugar a embriones y plantas haploides y doble-haploides. Este proceso es de gran interes basico y aplicado en biotecnologia y mejora vegetal para la obtencion rapida de nuevas variedades, sin embargo aun tiene importantes limitaciones en su explotacion por su baja eficiencia en muchas especies de interes economico. La limitacion en la aplicacion de este proceso es debida a que los mecanismos de induccion y progresion de la embriogenesis de microsporas no estan todavia completamente dilucidados. La monocotiledonea Hordeum vulgare (cebada) y la dicotiledonea Brassica napus (colza) son especies modelo para este proceso, en las cuales se induce embriogenesis directa en cultivos de microsporas aisladas en medio liquido, mediante tratamientos de estres con diferentes temperaturas...
7 citations
Cites background from "Epigenetic control of plant senesce..."
...46 marks can regulate the structure and function of chromatin (Ay et al. 2014; Jenuwein and Allis 2001; Ozanne and Constancia 2007)....
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...2014), the senescence (Ay et al. 2014; Woo et al. 2013), and the flowering (Müller and Goodrich 2011)....
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TL;DR: The results prove a senescence-specific mechanism, altering histone modification marks at distinct sequences of the senescences-associated gene HvS40 and altering distribution of heterochromatic areas in the nuclei and global changes in chromatin structure duringsenescence were analyzed via immunocytology.
Abstract: The barley gene HvS40, encoding a putative regulator of leaf senescence, is strongly induced during leaf senescence. As shown by chromatin immunoprecipitation, euchromatic histone modification H3K9ac is added at promoter close to ATG and coding sequence of HvS40 after onset of senescence. In parallel, level of heterochromatic H3K9me2 decreases at this gene. Bisulfite sequencing revealed no DNA-methylation in this region, but a heavily methylated DNA-island, starting 664 bp upstream from translational start site in both, mature and senescent leaves. A decrease in DNA methylation in senescing leaves could be shown at one specific CpG motif at the end of this methylation island. In addition, global changes in chromatin structure during senescence were analyzed via immunocytology, revealing senescence-associated changes in spatial distribution of heterochromatic H3K9me2 patterns in the nuclei. Our results prove a senescence-specific mechanism, altering histone modification marks at distinct sequences of the senescence-associated gene HvS40 and altering distribution of heterochromatic areas in the nuclei.
7 citations
Cites background from "Epigenetic control of plant senesce..."
...Global expression studies of senescence regulatory genes revealed that by SUVH2 overexpression activation of especially SAGs is impaired (Ay et al. 2014a)....
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...…acetylation and phosphorylation of mostly N-terminal amino acids, DNA methylation, chromatin remodeling factors and also small noncoding RNAs (Zilberman and Henikoff 2007; Pfluger and Wagner 2007; Zhou et al. 2010; Wollmann and Berger 2012; Jerzmanowski 2007; Humbeck 2013; Ay et al. 2014b)....
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...…of Genetics, Institute of Biology, Martin-Luther University Halle-Wittenberg, Weinbergweg 10, 06120 Halle, Germany 1 3 finger, MYB and AP2-EREBP families (Guo et al. 2004; Buchanan-Wollaston et al. 2005; Breeze et al. 2011; Balazadeh et al. 2008; Ay et al. 2014a; Christiansen and Gregersen 2014)....
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...…those senescence-specific up-regulated genes, generally referred to as senescence-associated genes (SAGs), are many regulatory genes mostly encoding transcription factors which direct senescence-specific reprogramming of gene expression (Lim et al. 2007; Balazadeh et al. 2008; Ay et al. 2014a)....
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TL;DR: It is suggested that phytohormonal regulation of senescence in roots and leaves is organ-specific and shown that the regulation of ABA and JA metabolism is tightly regulated duringsenescence processes in both leaves and roots.
Abstract: Plant senescence is a highly regulated process that allows nutrients to be mobilized from dying tissues to other organs. Despite that senescence has been extensively studied in leaves, the senescence of ephemeral organs located underground is still poorly understood, especially in the context of phytohormone engagement. The present study focused on filling this knowledge gap by examining the roles of abscisic acid (ABA) and jasmonate in the regulation of senescence of fine, absorptive roots and leaves of Populus trichocarpa. Immunohistochemical (IHC), chromatographic, and molecular methods were utilized to achieve this objective. A transcriptomic analysis identified significant changes in gene expression that were associated with the metabolism and signal transduction of phytohormones, especially ABA and jasmonate. The increased level of these phytohormones during senescence was detected in both organs and was confirmed by IHC. Based on the obtained data, we suggest that phytohormonal regulation of senescence in roots and leaves is organ-specific. We have shown that the regulation of ABA and JA metabolism is tightly regulated during senescence processes in both leaves and roots. The results were discussed with respect to the role of ABA in cold tolerance and the role of JA in resistance to pathogens.
7 citations
Cites background from "Epigenetic control of plant senesce..."
...Specifically, genes that are up-regulated during senescence are termed Senescence-Associated Genes (SAGs), while genes that are down-regulated are called Senescence down-regulated genes (SDGs) [31]....
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References
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TL;DR: The surface of nucleosomes is studded with a multiplicity of modifications that can dictate the higher-order chromatin structure in which DNA is packaged and can orchestrate the ordered recruitment of enzyme complexes to manipulate DNA.
10,046 citations
TL;DR: It is proposed that this epigenetic marking system represents a fundamental regulatory mechanism that has an impact on most, if not all, chromatin-templated processes, with far-reaching consequences for cell fate decisions and both normal and pathological development.
Abstract: Chromatin, the physiological template of all eukaryotic genetic information, is subject to a diverse array of posttranslational modifications that largely impinge on histone amino termini, thereby regulating access to the underlying DNA. Distinct histone amino-terminal modifications can generate synergistic or antagonistic interaction affinities for chromatin-associated proteins, which in turn dictate dynamic transitions between transcriptionally active or transcriptionally silent chromatin states. The combinatorial nature of histone amino-terminal modifications thus reveals a “histone code” that considerably extends the information potential of the genetic code. We propose that this epigenetic marking system represents a fundamental regulatory mechanism that has an impact on most, if not all, chromatin-templated processes, with far-reaching consequences for cell fate decisions and both normal and pathological development.
9,309 citations
TL;DR: The X-ray crystal structure of the nucleosome core particle of chromatin shows in atomic detail how the histone protein octamer is assembled and how 146 base pairs of DNA are organized into a superhelix around it.
Abstract: The X-ray crystal structure of the nucleosome core particle of chromatin shows in atomic detail how the histone protein octamer is assembled and how 146 base pairs of DNA are organized into a superhelix around it. Both histone/histone and histone/DNA interactions depend on the histone fold domains and additional, well ordered structure elements extending from this motif. Histone amino-terminal tails pass over and between the gyres of the DNA superhelix to contact neighbouring particles. The lack of uniformity between multiple histone/DNA-binding sites causes the DNA to deviate from ideal superhelix geometry.
7,841 citations
TL;DR: Drawing on insights from both plants and animals should deepen the understanding of the regulation and biological significance of DNA methylation.
Abstract: Cytosine DNA methylation is a stable epigenetic mark that is crucial for diverse biological processes, including gene and transposon silencing, imprinting and X chromosome inactivation. Recent findings in plants and animals have greatly increased our understanding of the pathways used to accurately target, maintain and modify patterns of DNA methylation and have revealed unanticipated mechanistic similarities between these organisms. Key roles have emerged for small RNAs, proteins with domains that bind methylated DNA and DNA glycosylases in these processes. Drawing on insights from both plants and animals should deepen our understanding of the regulation and biological significance of DNA methylation.
3,180 citations
TL;DR: This work has shown that transcription occurs against a backdrop of mixtures of complex modifications, which probably have several roles, and suggests that a more likely model is of a sophisticated, nuanced chromatin 'language' in which different combinations of basic building blocks yield dynamic functional outcomes.
Abstract: An important development in understanding the influence of chromatin on gene regulation has been the finding that DNA methylation and histone post-translational modifications lead to the recruitment of protein complexes that regulate transcription. Early interpretations of this phenomenon involved gene regulation reflecting predictive activating or repressing types of modification. However, further exploration reveals that transcription occurs against a backdrop of mixtures of complex modifications, which probably have several roles. Although such modifications were initially thought to be a simple code, a more likely model is of a sophisticated, nuanced chromatin 'language' in which different combinations of basic building blocks yield dynamic functional outcomes.
2,674 citations