Faculty Opinions recommendation of CLE14 functions as a "brake signal" suppressing age-dependent and stress-induced leaf senescence through promoting JUB1-mediated ROS scavenge in Arabidopsis.

Flag leaf senescence is an important biological process that drives the remobilization of nutrients to the growing organs of rice. Leaf senescence is controlled by genetic information via gene expression and epigenetic modification, but the precise mechanism is as of yet unclear. Here, we analyzed genome-wide acetylated lysine residue 9 of histone H3 (H3K9ac) enrichment by chromatin immunoprecipitation-sequencing (ChIP-seq) and examined its association with transcriptomes by RNA-seq during flag leaf aging in rice (Oryza sativa). We found that genome-wide H3K9 acetylation levels increased with age-dependent senescence in rice flag leaf, and there was a positive correlation between the density and breadth of H3K9ac and gene expression and transcript elongation. A set of 1,249 up-regulated, differentially expressed genes (DEGs) and 996 down-regulated DEGs showing a strong relationship between temporal changes in gene expression and gain/loss of H3K9ac was observed during rice flag leaf aging. We produced a landscape of H3K9 acetylation- modified gene expression targets that includes known senescence-associated genes, metabolism-related genes, as well as miRNA biosynthesis- related genes. Our findings reveal a complex regulatory network of metabolism- and senescence-related pathways mediated by H3K9ac and also elucidate patterns of H3K9ac-mediated regulation of gene expression during flag leaf aging in rice.

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A WRKY transcription factor, TaWRKY42-B, facilitates initiation of leaf senescence by promoting jasmonic acid biosynthesis

BMC Plant Biology ◽

10.1186/s12870-020-02650-7 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Ming-Ming Zhao ◽

Xiao-Wen Zhang ◽

Yong-Wei Liu ◽

Ke Li ◽

Qi Tan ◽

...

Keyword(s):

Leaf Senescence ◽

Expression Profiles ◽

Functional Characterization ◽

Wrky Transcription Factor ◽

Positive Role ◽

Environmental Signals ◽

Source To Sink ◽

Age Dependent ◽

Functional Investigation

Abstract Background Leaf senescence comprises numerous cooperative events, integrates environmental signals with age-dependent developmental cues, and coordinates the multifaceted deterioration and source-to-sink allocation of nutrients. In crops, leaf senescence has long been regarded as an essential developmental stage for productivity and quality, whereas functional characterization of candidate genes involved in the regulation of leaf senescence has, thus far, been limited in wheat. Results In this study, we analyzed the expression profiles of 97 WRKY transcription factors (TFs) throughout the progression of leaf senescence in wheat and subsequently isolated a potential regulator of leaf senescence, TaWRKY42-B, for further functional investigation. By phenotypic and physiological analyses in TaWRKY42-B-overexpressing Arabidopsis plants and TaWRKY42-B-silenced wheat plants, we confirmed the positive role of TaWRKY42-B in the initiation of developmental and dark-induced leaf senescence. Furthermore, our results revealed that TaWRKY42-B promotes leaf senescence mainly by interacting with a JA biosynthesis gene, AtLOX3, and its ortholog, TaLOX3, which consequently contributes to the accumulation of JA content. In the present study, we also demonstrated that TaWRKY42-B was functionally conserved with AtWRKY53 in the initiation of age-dependent leaf senescence. Conclusion Our results revealed a novel positive regulator of leaf senescence, TaWRKY42-B, which mediates JA-related leaf senescence via activation of JA biosynthesis and has the potential to be a target gene for molecular breeding in wheat.

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Gene Expression Changes Occurring at Bolting Time are Associated with Leaf Senescence in Arabidopsis

10.1101/2020.05.29.109306 ◽

2020 ◽

Author(s):

Will E Hinckley ◽

Judy A. Brusslan

Keyword(s):

Gene Expression ◽

Phase Transition ◽

Time Series ◽

Leaf Senescence ◽

Molecular Mechanisms ◽

Rna Seq ◽

Age Dependent ◽

Temporal Coupling ◽

Rosette Leaf ◽

Bolting Time

AbstractIn plants, the vegetative to reproductive phase transition (termed bolting in Arabidopsis) generally precedes age-dependent leaf senescence (LS). Many studies describe a temporal link between bolting time and LS, as plants that bolt early, senesce early, and plants that bolt late, senesce late. However, the molecular mechanisms underlying this relationship are unknown and are potentially agriculturally important, as they may allow for the development of crops that can overcome early LS caused by stress-related early phase transition. We hypothesized that gene expression changes associated with bolting time were regulating LS. We used a mutant that displays both early bolting and early LS as a model to test this hypothesis. An RNA-seq time series experiment was completed to compare the early bolting mutant to vegetative WT plants of the same age. This allowed us to identify bolting time-associated genes (BAGs) expressed in an older rosette leaf at the time of inflorescence emergence. The BAG list contains many well characterized LS regulators (ORE1, WRKY45, NAP, WRKY28), and GO analysis revealed enrichment for LS and LS-related processes. These bolting associated LS regulators likely contribute to the temporal coupling of bolting time to LS.

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AINTEGUMENTA negatively regulates age-dependent leaf senescence downstream of AUXIN RESPONSE FACTOR 2 in Arabidopsis thaliana

Plant Biotechnology ◽

10.5511/plantbiotechnology.16.0222a ◽

2016 ◽

Vol 33 (2) ◽

pp. 71-76 ◽

Cited By ~ 8

Author(s):

Guanping Feng ◽

Qiang Xu ◽

Zhenyang Wang ◽

Qiangjiu Zhuoma

Keyword(s):

Arabidopsis Thaliana ◽

Leaf Senescence ◽

Auxin Response Factor ◽

Response Factor ◽

Auxin Response ◽

Age Dependent

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The role of leaf hydraulic conductance dynamics on the timing of leaf senescence

Functional Plant Biology ◽

10.1071/fp13033 ◽

2014 ◽

Vol 41 (1) ◽

pp. 37 ◽

Cited By ~ 4

Author(s):

Juan Pablo Giraldo ◽

James K. Wheeler ◽

Brett A. Huggett ◽

N. Michele Holbrook

Keyword(s):

Leaf Senescence ◽

Acer Saccharum ◽

Tropical Trees ◽

Hydraulic Conductance ◽

Leaf Hydraulic Conductance ◽

Leaf Vein ◽

Solanum Lycopersicum L ◽

Temperate Trees ◽

Age Dependent ◽

Proportional Increase

We tested the hypothesis that an age-dependent reduction in leaf hydraulic conductance (Kleaf) influences the timing of leaf senescence via limitation of the stomatal aperture on xylem compound delivery to leaves of tomato (Solanum lycopersicum L.), the tropical trees Anacardium excelsum Kunth, Pittoniotis trichantha Griseb, and the temperate trees Acer saccharum Marsh. and Quercus rubra L. The onset of leaf senescence was preceded by a decline in Kleaf in tomato and the tropical trees, but not in the temperate trees. Age-dependent changes in Kleaf in tomato were driven by a reduction in leaf vein density without a proportional increase in the xylem hydraulic supply. A decline in stomatal conductance accompanied Kleaf reduction with age in tomato but not in tropical and temperate tree species. Experimental manipulations that reduce the flow of xylem-transported compounds into leaves with open stomata induced early leaf senescence in tomato and A. excelsum, but not in P. trichantha, A. saccharum and Q. rubra leaves. We propose that in tomato, a reduction in Kleaf limits the delivery of xylem-transported compounds into the leaves, thus making them vulnerable to senescence. In the tropical evergreen tree A. excelsum, xylem-transported compounds may play a role in signalling the timing of senescence but are not under leaf hydraulic regulation; leaf senescence in the deciduous trees A. trichanta, A. saccharum and Q. rubra is not influenced by leaf vascular transport.

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Circadian control of ORE1 by PRR9 positively regulates leaf senescence in Arabidopsis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1722407115 ◽

2018 ◽

Vol 115 (33) ◽

pp. 8448-8453 ◽

Cited By ~ 38

Author(s):

Hyunmin Kim ◽

Hyo Jung Kim ◽

Quy Thi Vu ◽

Sukjoon Jung ◽

C. Robertson McClung ◽

...

Keyword(s):

Circadian Clock ◽

Leaf Senescence ◽

Posttranscriptional Regulation ◽

Clock Genes ◽

Response Regulator ◽

Early Flowering ◽

Physiological Alterations ◽

Circadian Control ◽

Age Dependent ◽

Pseudo Response Regulator

The circadian clock coordinates the daily cyclic rhythm of numerous biological processes by regulating a large portion of the transcriptome. In animals, the circadian clock is involved in aging and senescence, and circadian disruption by mutations in clock genes frequently accelerates aging. Conversely, aging alters circadian rhythmicity, which causes age-associated physiological alterations. However, interactions between the circadian clock and aging have been rarely studied in plants. Here, we investigated potential roles for the circadian clock in the regulation of leaf senescence in plants. Members of the evening complex in Arabidopsis circadian clock, EARLY FLOWERING 3 (ELF3), EARLY FLOWERING 4 (ELF4), and LUX ARRHYTHMO (LUX), as well as the morning component PSEUDO-RESPONSE REGULATOR 9 (PRR9), affect both age-dependent and dark-induced leaf senescence. The circadian clock regulates the expression of several senescence-related transcription factors. In particular, PRR9 binds directly to the promoter of the positive aging regulator ORESARA1 (ORE1) gene to promote its expression. PRR9 also represses miR164, a posttranscriptional repressor of ORE1. Consistently, genetic analysis revealed that delayed leaf senescence of a prr9 mutant was rescued by ORE1 overexpression. Thus, PRR9, a core circadian component, is a key regulator of leaf senescence via positive regulation of ORE1 through a feed-forward pathway involving posttranscriptional regulation by miR164 and direct transcriptional regulation. Our results indicate that, in plants, the circadian clock and leaf senescence are intimately interwoven as are the clock and aging in animals.

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Ring/U-Box Protein AtUSR1 Functions in Promoting Leaf Senescence Through JA Signaling Pathway in Arabidopsis

Frontiers in Plant Science ◽

10.3389/fpls.2020.608589 ◽

2020 ◽

Vol 11 ◽

Author(s):

Zenglin Zhang ◽

Mengmeng Xu ◽

Yongfeng Guo

Keyword(s):

Transcription Factor ◽

Signaling Pathway ◽

Leaf Senescence ◽

Luciferase Assay ◽

Significant Delay ◽

Delayed Senescence ◽

Age Dependent ◽

Ja Signaling ◽

Senescence Phenotype

Leaf senescence is regulated by a large number of internal and environmental factors. Here, we report that AtUSR1 (U-box Senescence Related 1) which encodes a plant Ring/U-box protein, is involved in age-dependent and dark-induced leaf senescence in Arabidopsis. Expression of AtUSR1 gene in leaves was up-regulated in darkness and during aging. Plants of usr1, an AtUSR1 gene knock-down mutant, showed a significant delay in age-dependent and dark-induced leaf senescence and the delayed senescence phenotype was rescued when the AtUSR1 gene was transferred back to the mutant plants. Meanwhile, overexpression of AtUSR1 caused accelerated leaf senescence. Furthermore, the role of AtUSR1 in regulating leaf senescence is related to MYC2-mediuated jasmonic acid (JA) signaling pathway. MeJA treatments promoted the accumulation of AtUSR1 transcripts and this expression activation was dependent on the function of MYC2, a key transcription factor in JA signaling. Dual-luciferase assay results indicated that MYC2 promoted the expression of AtUSR1. Overexpression of AtUSR1 in myc2 mutant plants showed precocious senescence, while myc2 mutation alone caused a delay in leaf senescence, suggesting that AtUSR1 functions downstream to MYC2 in the JA signaling pathway in promoting leaf senescence.

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