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.
Highlights
Senescence is a major developmental transition in plants that requires a massive reprogramming of gene expression and includes various layers of regulations
DNA methylation in plant genomes is more extensive than in animals [11], and it might be either symmetric, as with CG, which is mainly modulated by DNA- METHYLTRANSFERASE-1 (MET1), or CHG (H is A, T or C), which is mainly modulated by CHROMOMETHYLASE 3 (CMT3), or asymmetric, as with CHH DNA-methylation, which is usually controlled by DOMAINS-REARRANGED METHYLTRANSFERASEs (DRMs) [11]
Even though wild-type plants showed increased levels of H3K9ac, of the HvS40 gene, under drought stress, indicating the role of epigenetic mechanisms in response to drought stress, no significant increase in H3K9ac was seen in RNAi-W1 transgenic plants
Summary
Senescence (from the Latin word “senescere”, meaning to grow old) is the final, main developmental phase transition in plants. Epigenetic mechanisms that are known to play an important role in regulating the transition of plants to the developmental stages have a key impact on senescence [7]. They dynamically alter the chromatin structure at certain loci, which makes the DNA accessible (euchromatin) or inaccessible (heterochromatin) for TFs and thereby activate or inactivate the senescence-related genes, respectively [2]. Expression of epigenetic senescence could help to understand if senescence are Arabidopsis drought stress-responsive genes which are upregulated is associated with changes in the epigenetic pattern (e.g., DNA methylation) of those during leaf senescence, and RD20 their(responsive expressiontoisdehydration-20). The name for the main factors in every step is given
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