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Raz A, Dahan-Meir T, Melamed-Bessudo C, Leshkowitz D, Levy AA. Redistribution of Meiotic Crossovers Along Wheat Chromosomes by Virus-Induced Gene Silencing. FRONTIERS IN PLANT SCIENCE 2020; 11:635139. [PMID: 33613593 PMCID: PMC7890124 DOI: 10.3389/fpls.2020.635139] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 12/31/2020] [Indexed: 05/08/2023]
Abstract
Meiotic recombination is the main driver of genetic diversity in wheat breeding. The rate and location of crossover (CO) events are regulated by genetic and epigenetic factors. In wheat, most COs occur in subtelomeric regions but are rare in centromeric and pericentric areas. The aim of this work was to increase COs in both "hot" and "cold" chromosomal locations. We used Virus-Induced gene Silencing (VIGS) to downregulate the expression of recombination-suppressing genes XRCC2 and FANCM and of epigenetic maintenance genes MET1 and DDM1 during meiosis. VIGS suppresses genes in a dominant, transient and non-transgenic manner, which is convenient in wheat, a hard-to-transform polyploid. F1 hybrids of a cross between two tetraploid lines whose genome was fully sequenced (wild emmer and durum wheat), were infected with a VIGS vector ∼ 2 weeks before meiosis. Recombination was measured in F2 seedlings derived from F1-infected plants and non-infected controls. We found significant up and down-regulation of CO rates along subtelomeric regions as a result of silencing either MET1, DDM1 or XRCC2 during meiosis. In addition, we found up to 93% increase in COs in XRCC2-VIGS treatment in the pericentric regions of some chromosomes. Silencing FANCM showed no effect on CO. Overall, we show that CO distribution was affected by VIGS treatments rather than the total number of COs which did not change. We conclude that transient silencing of specific genes during meiosis can be used as a simple, fast and non-transgenic strategy to improve breeding abilities in specific chromosomal regions.
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Affiliation(s)
- Amir Raz
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
- Department of Plant Science, MIGAL Galilee Research Institute, Kiryat Shmona, Israel
- Amir Raz,
| | - Tal Dahan-Meir
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Cathy Melamed-Bessudo
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Dena Leshkowitz
- Bioinformatics Unit, Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Avraham A. Levy
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
- *Correspondence: Avraham A. Levy,
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152
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Flores-Vergara MA, Oneal E, Costa M, Villarino G, Roberts C, De Luis Balaguer MA, Coimbra S, Willis J, Franks RG. Developmental Analysis of Mimulus Seed Transcriptomes Reveals Functional Gene Expression Clusters and Four Imprinted, Endosperm-Expressed Genes. FRONTIERS IN PLANT SCIENCE 2020; 11:132. [PMID: 32161609 PMCID: PMC7052496 DOI: 10.3389/fpls.2020.00132] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 01/28/2020] [Indexed: 05/15/2023]
Abstract
The double fertilization of the female gametophyte initiates embryogenesis and endosperm development in seeds via the activation of genes involved in cell differentiation, organ patterning, and growth. A subset of genes expressed in endosperm exhibit imprinted expression, and the correct balance of gene expression between parental alleles is critical for proper endosperm and seed development. We use a transcriptional time series analysis to identify genes that are associated with key shifts in seed development, including genes associated with secondary cell wall synthesis, mitotic cell cycle, chromatin organization, auxin synthesis, fatty acid metabolism, and seed maturation. We relate these genes to morphological changes in Mimulus seeds. We also identify four endosperm-expressed transcripts that display imprinted (paternal) expression bias. The imprinted status of these four genes is conserved in other flowering plants, suggesting that they are functionally important in endosperm development. Our study explores gene regulatory dynamics in a species with ab initio cellular endosperm development, broadening the taxonomic focus of the literature on gene expression in seeds. Moreover, it is the first to validate genes with imprinted endosperm expression in Mimulus guttatus, and will inform future studies on the genetic causes of seed failure in this model system.
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Affiliation(s)
- Miguel A. Flores-Vergara
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, United States
| | - Elen Oneal
- Department of Biology, Duke University, Durham, NC, United States
- *Correspondence: Elen Oneal,
| | - Mario Costa
- GreenUPorto, Sustainable Agrifood Production Research Centre, Biology Department, Faculty of Sciences, University of Porto, Porto, Portugal
| | - Gonzalo Villarino
- Biology Department, San Diego State University, San Diego, CA, United States
| | - Caitlyn Roberts
- Department of Biology, Berea College, Berea, KY, United States
| | | | - Sílvia Coimbra
- GreenUPorto, Sustainable Agrifood Production Research Centre, Biology Department, Faculty of Sciences, University of Porto, Porto, Portugal
| | - John Willis
- Department of Biology, Duke University, Durham, NC, United States
| | - Robert G. Franks
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, United States
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153
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Kenchanmane Raju SK, Ritter EJ, Niederhuth CE. Establishment, maintenance, and biological roles of non-CG methylation in plants. Essays Biochem 2019; 63:743-755. [PMID: 31652316 PMCID: PMC6923318 DOI: 10.1042/ebc20190032] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 09/18/2019] [Accepted: 09/20/2019] [Indexed: 12/18/2022]
Abstract
Cytosine DNA methylation is prevalent throughout eukaryotes and prokaryotes. While most commonly thought of as being localized to dinucleotide CpG sites, non-CG sites can also be modified. Such non-CG methylation is widespread in plants, occurring at trinucleotide CHG and CHH (H = A, T, or C) sequence contexts. The prevalence of non-CG methylation in plants is due to the plant-specific CHROMOMETHYLASE (CMT) and RNA-directed DNA Methylation (RdDM) pathways. These pathways have evolved through multiple rounds of gene duplication and gene loss, generating epigenomic variation both within and between species. They regulate both transposable elements and genes, ensure genome integrity, and ultimately influence development and environmental responses. In these capacities, non-CG methylation influence and shape plant genomes.
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Affiliation(s)
| | | | - Chad E Niederhuth
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, U.S.A
- AgBioResearch, Michigan State University, East Lansing, MI 48824, U.S.A
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154
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Han Q, Bartels A, Cheng X, Meyer A, An YQC, Hsieh TF, Xiao W. Epigenetics Regulates Reproductive Development in Plants. PLANTS 2019; 8:plants8120564. [PMID: 31810261 PMCID: PMC6963493 DOI: 10.3390/plants8120564] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 11/23/2019] [Accepted: 11/27/2019] [Indexed: 12/20/2022]
Abstract
Seed, resulting from reproductive development, is the main nutrient source for human beings, and reproduction has been intensively studied through genetic, molecular, and epigenetic approaches. However, how different epigenetic pathways crosstalk and integrate to regulate seed development remains unknown. Here, we review the recent progress of epigenetic changes that affect chromatin structure, such as DNA methylation, polycomb group proteins, histone modifications, and small RNA pathways in regulating plant reproduction. In gametogenesis of flowering plants, epigenetics is dynamic between the companion cell and gametes. Cytosine DNA methylation occurs in CG, CHG, CHH contexts (H = A, C, or T) of genes and transposable elements, and undergoes dynamic changes during reproduction. Cytosine methylation in the CHH context increases significantly during embryogenesis, reaches the highest levels in mature embryos, and decreases as the seed germinates. Polycomb group proteins are important transcriptional regulators during seed development. Histone modifications and small RNA pathways add another layer of complexity in regulating seed development. In summary, multiple epigenetic pathways are pivotal in regulating seed development. It remains to be elucidated how these epigenetic pathways interplay to affect dynamic chromatin structure and control reproduction.
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Affiliation(s)
- Qiang Han
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA (A.B.); (X.C.)
| | - Arthur Bartels
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA (A.B.); (X.C.)
| | - Xi Cheng
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA (A.B.); (X.C.)
| | - Angela Meyer
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA (A.B.); (X.C.)
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Yong-Qiang Charles An
- US Department of Agriculture, Agricultural Research Service, Midwest Area, Plant Genetics Research Unit, Donald Danforth Plant Science Center, MO 63132, USA;
| | - Tzung-Fu Hsieh
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA;
- Plants for Human Health Institute, North Carolina State University, North Carolina Research Campus, Kannapolis, NC 28081, USA
| | - Wenyan Xiao
- Department of Biology, Saint Louis University, St. Louis, MO 63103, USA (A.B.); (X.C.)
- Correspondence: ; Tel.: +1-314-977-2547
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155
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Zhu G, Chang Y, Xu X, Tang K, Chen C, Lei M, Zhu JK, Duan CG. EXPORTIN 1A prevents transgene silencing in Arabidopsis by modulating nucleo-cytoplasmic partitioning of HDA6. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2019; 61:1243-1254. [PMID: 30697937 DOI: 10.1111/jipb.12787] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Accepted: 01/25/2019] [Indexed: 05/28/2023]
Abstract
In eukaryotic cells, transport of macromolecules across the nuclear envelope is an essential process that ensures rapid exchange of cellular components, including protein and RNA molecules. Chromatin regulators involved in epigenetic control are among the molecules exported across the nuclear envelope, but the significance of this nucleo-cytoplasmic trafficking is not well understood. Here, we use a forward screen to isolate XPO1A (a nuclear export receptor in Arabidopsis) as an anti-silencing factor that protects transgenes from transcriptional silencing. Loss-of-function of XPO1A leads to locus-specific DNA hypermethylation at transgene promoters and some endogenous loci. We found that XPO1A directly interacts with histone deacetylase HDA6 in vivo and that the xpo1a mutation causes increased nuclear retention of HDA6 protein and results in reduced histone acetylation and enhanced transgene silencing. Our results reveal a new mechanism of epigenetic regulation through the modulation of XPO1A-dependent nucleo-cytoplasm partitioning of a chromatin regulator.
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Affiliation(s)
- Guohui Zhu
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Yanan Chang
- Shanghai Center for Plant Stress Biology and Center of Excellence for Molecular Plant Sciences, the Chinese Academy of Sciences, Shanghai, 201602, China
- The University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xuezhong Xu
- College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Kai Tang
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA
- Shanghai Center for Plant Stress Biology and Center of Excellence for Molecular Plant Sciences, the Chinese Academy of Sciences, Shanghai, 201602, China
| | - Chunxiang Chen
- Shanghai Center for Plant Stress Biology and Center of Excellence for Molecular Plant Sciences, the Chinese Academy of Sciences, Shanghai, 201602, China
- The University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Mingguang Lei
- Shanghai Center for Plant Stress Biology and Center of Excellence for Molecular Plant Sciences, the Chinese Academy of Sciences, Shanghai, 201602, China
| | - Jian-Kang Zhu
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA
- Shanghai Center for Plant Stress Biology and Center of Excellence for Molecular Plant Sciences, the Chinese Academy of Sciences, Shanghai, 201602, China
| | - Cheng-Guo Duan
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN, 47907, USA
- Shanghai Center for Plant Stress Biology and Center of Excellence for Molecular Plant Sciences, the Chinese Academy of Sciences, Shanghai, 201602, China
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156
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Yang Q, Jiang W, Hou P. Emerging role of PI3K/AKT in tumor-related epigenetic regulation. Semin Cancer Biol 2019; 59:112-124. [DOI: 10.1016/j.semcancer.2019.04.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 03/14/2019] [Accepted: 04/01/2019] [Indexed: 01/23/2023]
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157
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Xu J, Chen G, Hermanson PJ, Xu Q, Sun C, Chen W, Kan Q, Li M, Crisp PA, Yan J, Li L, Springer NM, Li Q. Population-level analysis reveals the widespread occurrence and phenotypic consequence of DNA methylation variation not tagged by genetic variation in maize. Genome Biol 2019; 20:243. [PMID: 31744513 PMCID: PMC6862797 DOI: 10.1186/s13059-019-1859-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Accepted: 10/10/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND DNA methylation can provide a source of heritable information that is sometimes entirely uncoupled from genetic variation. However, the extent of this uncoupling and the roles of DNA methylation in shaping diversity of both gene expression and phenotypes are hotly debated. Here, we investigate the genetic basis and biological functions of DNA methylation at a population scale in maize. RESULTS We perform targeted DNA methylation profiling for a diverse panel of 263 maize inbred genotypes. All genotypes show similar levels of DNA methylation globally, highlighting the importance of DNA methylation in maize development. Nevertheless, we identify more than 16,000 differentially methylated regions (DMRs) that are distributed across the 10 maize chromosomes. Genome-wide association analysis with high-density genetic markers reveals that over 60% of the DMRs are not tagged by SNPs, suggesting the presence of unique information in DMRs. Strong associations between DMRs and the expression of many genes are identified in both the leaf and kernel tissues, pointing to the biological significance of methylation variation. Association analysis with 986 metabolic traits suggests that DNA methylation is associated with phenotypic variation of 156 traits. There are some traits that only show significant associations with DMRs and not with SNPs. CONCLUSIONS These results suggest that DNA methylation can provide unique information to explain phenotypic variation in maize.
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Affiliation(s)
- Jing Xu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Guo Chen
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
- Institute of Nuclear and Biological Technology, Xinjiang Academy of Agricultural Sciences, Urumqi, 830091 China
| | - Peter J. Hermanson
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108 USA
| | - Qiang Xu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Changshuo Sun
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Wenqing Chen
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Qiuxin Kan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Minqi Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Peter A. Crisp
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108 USA
| | - Jianbing Yan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Lin Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
| | - Nathan M. Springer
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108 USA
| | - Qing Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070 China
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158
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Zangi M, Bagherieh Najjar MB, Golalipour M, Aghdasi M. met1 DNA Methyltransferase Controls TERT Gene Expression: A New Insight to The Role of Telomerase in Development. CELL JOURNAL 2019; 22:71-74. [PMID: 31606969 PMCID: PMC6791074 DOI: 10.22074/cellj.2020.6290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 12/25/2018] [Indexed: 12/11/2022]
Abstract
Objective: DNA methylation systems are essential for proper embryo development. Methylation defects lead to
developmental abnormalities. Furthermore, changes in telomerase gene expression can affect stability of chromosomes
and produces abnormal growth. Therefore, defects in both methylation and telomerase gene expression can lead to
developmental abnormalities. We hypothesized that mutation in the methylation systems may induce developmental
abnormalities through changing telomerase gene expression. Materials and Methods: In this experimental study, we used Arabidopsis thaliana (At) as a developmental model.
DNA was extracted from seedlings leaves. The grown plants were screened using polymerase chain reaction (PCR)
reactions. Total RNA was isolated from the mature leaves, stems and flowers of wild type and met1 mutants. For
gene expression analysis, cDNA was synthesized and then quantitative reverse transcription PCR (qRT-PCR) was
performed. Results: Telomerase gene expression level in homozygous met1 mutant plants showed ~14 fold increase compared
to normal plants. Furthermore, TERT expression in met1 heterozygous was~ 2 fold higher than the wild type plants. Conclusion: Our results suggested that TERT is a methyltransferase-regulated gene which may be involved in
developmental abnormities causing by mutation in met1 methyltransferase system.
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Affiliation(s)
- Maryam Zangi
- Department of Biology, Faculty of Science, Golestan University, Gorgan, Iran
| | | | - Masoud Golalipour
- Cellular and Molecular Research Center, Golestan University of Medical Sciences, Gorgan, Iran. Electronic Address:
| | - Mahnaz Aghdasi
- Department of Biology, Faculty of Science, Golestan University, Gorgan, Iran
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159
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Shafiq S, Zeb Q, Ali A, Sajjad Y, Nazir R, Widemann E, Liu L. Lead, Cadmium and Zinc Phytotoxicity Alter DNA Methylation Levels to Confer Heavy Metal Tolerance in Wheat. Int J Mol Sci 2019; 20:E4676. [PMID: 31547165 PMCID: PMC6801570 DOI: 10.3390/ijms20194676] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 09/16/2019] [Accepted: 09/17/2019] [Indexed: 11/16/2022] Open
Abstract
Being a staple food, wheat (Triticum aestivum) nutritionally fulfills all requirements of human health and also serves as a significant link in the food chain for the ingestion of pollutants by humans and animals. Therefore, the presence of the heavy metals such as lead (Pb) and cadmium (Cd) in soil is not only responsible for the reduction of wheat crop yield but also the potential threat for human and animal health. However, the link between DNA methylation and heavy metal stress tolerance in wheat has not been investigated yet. In this study, eight high yielding wheat varieties were screened based on their phenotype in response to Pb stress. Out of these, Pirsabak 2004 and Fakhar-e-sarhad were identified as Pb resistant and sensitive varieties, respectively. In addition, Pirsabak 2004 and Fakhar-e-sarhad varieties were also found resistant and sensitive to Cd and Zinc (Zn) stress, respectively. Antioxidant activity was decreased in Fakhar-e-sarhad compared with control in response to Pb/Cd/Zn stresses, but Fakhar-e-sarhad and Pirsabak 2004 accumulated similar levels of Pb, Cd and Zn in their roots. The expression of Heavy Metal ATPase 2 (TaHMA2) and ATP-Binding Cassette (TaABCC2/3/4) metal detoxification transporters are significantly upregulated in Pirsabak 2004 compared with Fakhar-e-sarhad and non-treated controls in response to Pb, Cd and Zn metal stresses. Consistent with upregulation of metal detoxification transporters, CG DNA hypomethylation was also found at the promoter region of these transporters in Pirsabak 2004 compared with Fakhar-e-sarhad and non-treated control, which indicates that DNA methylation regulates the expression of metal detoxification transporters to confer resistance against metal toxicity in wheat. This study recommends the farmers to cultivate Pirsabak 2004 variety in metal contaminated soils and also highlights that DNA methylation is associated with metal stress tolerance in wheat.
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Affiliation(s)
- Sarfraz Shafiq
- Department of Anatomy and Cell Biology, University of Western Ontario, 1151 Richmond St, London, ON N6A5B8, Canada.
- Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad campus, Pakhtunkhwa 22060, Pakistan.
| | - Qudsia Zeb
- College of Life Sciences, Capital Normal University, Beijing 100084, China.
| | - Asim Ali
- Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad campus, Pakhtunkhwa 22060, Pakistan.
| | - Yasar Sajjad
- Department of Biotechnology, COMSATS University Islamabad, Abbottabad campus, Pakhtunkhwa 22060, Pakistan.
| | - Rashid Nazir
- Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad campus, Pakhtunkhwa 22060, Pakistan.
| | - Emilie Widemann
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, Ontario, N6A5B8, Canada.
| | - Liangyu Liu
- College of Life Sciences, Capital Normal University, Beijing 100084, China.
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160
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Přibylová A, Čermák V, Tyč D, Fischer L. Detailed insight into the dynamics of the initial phases of de novo RNA-directed DNA methylation in plant cells. Epigenetics Chromatin 2019; 12:54. [PMID: 31511048 PMCID: PMC6737654 DOI: 10.1186/s13072-019-0299-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/22/2019] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Methylation of cytosines is an evolutionarily conserved epigenetic mark that is essential for the control of chromatin activity in many taxa. It acts mainly repressively, causing transcriptional gene silencing. In plants, de novo DNA methylation is established mainly by RNA-directed DNA-methylation pathway. Even though the protein machinery involved is relatively well-described, the course of the initial phases remains covert. RESULTS We show the first detailed description of de novo DNA-methylation dynamics. Since prevalent plant model systems do not provide the possibility to collect homogenously responding material in time series with short intervals, we developed a convenient system based on tobacco BY-2 cell lines with inducible production of siRNAs (from an RNA hairpin) guiding the methylation machinery to the CaMV 35S promoter controlling GFP reporter. These lines responded very synchronously, and a high level of promoter-specific siRNAs triggered rapid promoter methylation with the first increase observed already 12 h after the induction. The previous presence of CG methylation in the promoter did not affect the methylation dynamics. The individual cytosine contexts reacted differently. CHH methylation peaked at about 80% in 2 days and then declined, whereas CG and CHG methylation needed more time with CHG reaching practically 100% after 10 days. Spreading of methylation was only minimal outside the target region in accordance with the absence of transitive siRNAs. The low and stable proportion of 24-nt siRNAs suggested that Pol IV was not involved in the initial phases. CONCLUSIONS Our results show that de novo DNA methylation is a rapid process initiated practically immediately with the appearance of promoter-specific siRNAs and independently of the prior presence of methylcytosines at the target locus. The methylation was precisely targeted, and its dynamics varied depending on the cytosine sequence context. The progressively increasing methylation resulted in a smooth, gradual inhibition of the promoter activity, which was entirely suppressed in 2 days.
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Affiliation(s)
- Adéla Přibylová
- Department of Experimental Plant Biology, Charles University, Faculty of Science, 128 44, Prague, Czech Republic
| | - Vojtěch Čermák
- Department of Experimental Plant Biology, Charles University, Faculty of Science, 128 44, Prague, Czech Republic
| | - Dimitrij Tyč
- Department of Experimental Plant Biology, Charles University, Faculty of Science, 128 44, Prague, Czech Republic
| | - Lukáš Fischer
- Department of Experimental Plant Biology, Charles University, Faculty of Science, 128 44, Prague, Czech Republic.
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161
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Small RNA Mobility: Spread of RNA Silencing Effectors and its Effect on Developmental Processes and Stress Adaptation in Plants. Int J Mol Sci 2019; 20:ijms20174306. [PMID: 31484348 PMCID: PMC6747330 DOI: 10.3390/ijms20174306] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/28/2019] [Accepted: 08/30/2019] [Indexed: 01/22/2023] Open
Abstract
Plants are exposed every day to multiple environmental cues, and tight transcriptome reprogramming is necessary to control the balance between responses to stress and processes of plant growth. In this context, the silencing phenomena mediated by small RNAs can drive transcriptional and epigenetic regulatory modifications, in turn shaping plant development and adaptation to the surrounding environment. Mounting experimental evidence has recently pointed to small noncoding RNAs as fundamental players in molecular signalling cascades activated upon exposure to abiotic and biotic stresses. Although, in the last decade, studies on stress responsive small RNAs increased significantly in many plant species, the physiological responses triggered by these molecules in the presence of environmental stresses need to be further explored. It is noteworthy that small RNAs can move either cell-to-cell or systemically, thus acting as mobile silencing effectors within the plant. This aspect has great importance when physiological changes, as well as epigenetic regulatory marks, are inspected in light of plant environmental adaptation. In this review, we provide an overview of the categories of mobile small RNAs in plants, particularly focusing on the biological implications of non-cell autonomous RNA silencing in the stress adaptive response and epigenetic modifications.
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162
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Abstract
DNA methylation is a conserved epigenetic modification that is important for gene regulation and genome stability. Aberrant patterns of DNA methylation can lead to plant developmental abnormalities. A specific DNA methylation state is an outcome of dynamic regulation by de novo methylation, maintenance of methylation and active demethylation, which are catalysed by various enzymes that are targeted by distinct regulatory pathways. In this Review, we discuss DNA methylation in plants, including methylating and demethylating enzymes and regulatory factors, and the coordination of methylation and demethylation activities by a so-called methylstat mechanism; the functions of DNA methylation in regulating transposon silencing, gene expression and chromosome interactions; the roles of DNA methylation in plant development; and the involvement of DNA methylation in plant responses to biotic and abiotic stress conditions.
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163
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Wilkinson SW, Magerøy MH, López Sánchez A, Smith LM, Furci L, Cotton TEA, Krokene P, Ton J. Surviving in a Hostile World: Plant Strategies to Resist Pests and Diseases. ANNUAL REVIEW OF PHYTOPATHOLOGY 2019; 57:505-529. [PMID: 31470772 DOI: 10.1146/annurev-phyto-082718-095959] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
As primary producers, plants are under constant pressure to defend themselves against potentially deadly pathogens and herbivores. In this review, we describe short- and long-term strategies that enable plants to cope with these stresses. Apart from internal immunological strategies that involve physiological and (epi)genetic modifications at the cellular level, plants also employ external strategies that rely on recruitment of beneficial organisms. We discuss these strategies along a gradient of increasing timescales, ranging from rapid immune responses that are initiated within seconds to (epi)genetic adaptations that occur over multiple plant generations. We cover the latest insights into the mechanistic and evolutionary underpinnings of these strategies and present explanatory models. Finally, we discuss how knowledge from short-lived model species can be translated to economically and ecologically important perennials to exploit adaptive plant strategies and mitigate future impacts of pests and diseases in an increasingly interconnected and changing world.
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Affiliation(s)
- Samuel W Wilkinson
- Plant Production and Protection Institute and Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom;
- Department of Molecular Plant Biology, Division for Biotechnology and Plant Health, Norwegian Institute for Bioeconomy Research, 1431 Ås, Norway
| | - Melissa H Magerøy
- Department of Molecular Plant Biology, Division for Biotechnology and Plant Health, Norwegian Institute for Bioeconomy Research, 1431 Ås, Norway
| | - Ana López Sánchez
- Plant Production and Protection Institute and Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom;
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de Cantoblanco, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Lisa M Smith
- Plant Production and Protection Institute and Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom;
| | - Leonardo Furci
- Plant Production and Protection Institute and Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom;
| | - T E Anne Cotton
- Plant Production and Protection Institute and Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom;
| | - Paal Krokene
- Department of Molecular Plant Biology, Division for Biotechnology and Plant Health, Norwegian Institute for Bioeconomy Research, 1431 Ås, Norway
| | - Jurriaan Ton
- Plant Production and Protection Institute and Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom;
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164
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Schmitz RJ, Lewis ZA, Goll MG. DNA Methylation: Shared and Divergent Features across Eukaryotes. Trends Genet 2019; 35:818-827. [PMID: 31399242 DOI: 10.1016/j.tig.2019.07.007] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/01/2019] [Accepted: 07/15/2019] [Indexed: 02/02/2023]
Abstract
Chemical modification of nucleotide bases in DNA provides one mechanism for conveying information in addition to the genetic code. 5-methylcytosine (5mC) represents the most common chemically modified base in eukaryotic genomes. Sometimes referred to simply as DNA methylation, in eukaryotes 5mC is most prevalent at CpG dinucleotides and is frequently associated with transcriptional repression of transposable elements. However, 5mC levels and distributions are variable across phylogenies, and emerging evidence suggests that the functions of DNA methylation may be more diverse and complex than was previously appreciated. We summarize the current understanding of DNA methylation profiles and functions in different eukaryotic lineages.
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Affiliation(s)
- Robert J Schmitz
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Zachary A Lewis
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Mary G Goll
- Department of Genetics, University of Georgia, Athens, GA 30602, USA.
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165
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Grognet P, Timpano H, Carlier F, Aït-Benkhali J, Berteaux-Lecellier V, Debuchy R, Bidard F, Malagnac F. A RID-like putative cytosine methyltransferase homologue controls sexual development in the fungus Podospora anserina. PLoS Genet 2019; 15:e1008086. [PMID: 31412020 PMCID: PMC6709928 DOI: 10.1371/journal.pgen.1008086] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/26/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022] Open
Abstract
DNA methyltransferases are ubiquitous enzymes conserved in bacteria, plants and opisthokonta. These enzymes, which methylate cytosines, are involved in numerous biological processes, notably development. In mammals and higher plants, methylation patterns established and maintained by the cytosine DNA methyltransferases (DMTs) are essential to zygotic development. In fungi, some members of an extensively conserved fungal-specific DNA methyltransferase class are both mediators of the Repeat Induced Point mutation (RIP) genome defense system and key players of sexual reproduction. Yet, no DNA methyltransferase activity of these purified RID (RIP deficient) proteins could be detected in vitro. These observations led us to explore how RID-like DNA methyltransferase encoding genes would play a role during sexual development of fungi showing very little genomic DNA methylation, if any. To do so, we used the model ascomycete fungus Podospora anserina. We identified the PaRid gene, encoding a RID-like DNA methyltransferase and constructed knocked-out ΔPaRid defective mutants. Crosses involving P. anserina ΔPaRid mutants are sterile. Our results show that, although gametes are readily formed and fertilization occurs in a ΔPaRid background, sexual development is blocked just before the individualization of the dikaryotic cells leading to meiocytes. Complementation of ΔPaRid mutants with ectopic alleles of PaRid, including GFP-tagged, point-mutated and chimeric alleles, demonstrated that the catalytic motif of the putative PaRid methyltransferase is essential to ensure proper sexual development and that the expression of PaRid is spatially and temporally restricted. A transcriptomic analysis performed on mutant crosses revealed an overlap of the PaRid-controlled genetic network with the well-known mating-types gene developmental pathway common to an important group of fungi, the Pezizomycotina.
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Affiliation(s)
- Pierre Grognet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
| | - Hélène Timpano
- Université Paris-Sud, Institut de Génétique et Microbiologie UMR8621, Orsay, France, CNRS, Institut de Génétique et Microbiologie UMR8621, Orsay, France
| | - Florian Carlier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
| | - Jinane Aït-Benkhali
- Université Paris-Sud, Institut de Génétique et Microbiologie UMR8621, Orsay, France, CNRS, Institut de Génétique et Microbiologie UMR8621, Orsay, France
| | | | - Robert Debuchy
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
| | - Frédérique Bidard
- Université Paris-Sud, Institut de Génétique et Microbiologie UMR8621, Orsay, France, CNRS, Institut de Génétique et Microbiologie UMR8621, Orsay, France
| | - Fabienne Malagnac
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris‐Saclay, France
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166
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Wendte JM, Zhang Y, Ji L, Shi X, Hazarika RR, Shahryary Y, Johannes F, Schmitz RJ. Epimutations are associated with CHROMOMETHYLASE 3-induced de novo DNA methylation. eLife 2019; 8:e47891. [PMID: 31356150 PMCID: PMC6663294 DOI: 10.7554/elife.47891] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 07/19/2019] [Indexed: 12/20/2022] Open
Abstract
In many plant species, a subset of transcribed genes are characterized by strictly CG-context DNA methylation, referred to as gene body methylation (gbM). The mechanisms that establish gbM are unclear, yet flowering plant species naturally without gbM lack the DNA methyltransferase, CMT3, which maintains CHG (H = A, C, or T) and not CG methylation at constitutive heterochromatin. Here, we identify the mechanistic basis for gbM establishment by expressing CMT3 in a species naturally lacking CMT3. CMT3 expression reconstituted gbM through a progression of de novo CHG methylation on expressed genes, followed by the accumulation of CG methylation that could be inherited even following loss of the CMT3 transgene. Thus, gbM likely originates from the simultaneous targeting of loci by pathways that promote euchromatin and heterochromatin, which primes genes for the formation of stably inherited epimutations in the form of CG DNA methylation.
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Affiliation(s)
- Jered M Wendte
- Department of GeneticsUniversity of GeorgiaAthensUnited States
| | - Yinwen Zhang
- Institute of BioinformaticsUniversity of GeorgiaAthensUnited States
| | - Lexiang Ji
- Institute of BioinformaticsUniversity of GeorgiaAthensUnited States
| | - Xiuling Shi
- Department of GeneticsUniversity of GeorgiaAthensUnited States
| | - Rashmi R Hazarika
- Department of Plant ScienceTechnical University of MunichFreisingGermany
| | - Yadollah Shahryary
- Department of Plant ScienceTechnical University of MunichFreisingGermany
| | - Frank Johannes
- Department of Plant ScienceTechnical University of MunichFreisingGermany
- Institute for Advanced StudyTechnical University of MunichGarchingGermany
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167
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Wendte JM, Zhang Y, Ji L, Shi X, Hazarika RR, Shahryary Y, Johannes F, Schmitz RJ. Epimutations are associated with CHROMOMETHYLASE 3-induced de novo DNA methylation. eLife 2019. [PMID: 31356150 DOI: 10.7554/elife.47891.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
In many plant species, a subset of transcribed genes are characterized by strictly CG-context DNA methylation, referred to as gene body methylation (gbM). The mechanisms that establish gbM are unclear, yet flowering plant species naturally without gbM lack the DNA methyltransferase, CMT3, which maintains CHG (H = A, C, or T) and not CG methylation at constitutive heterochromatin. Here, we identify the mechanistic basis for gbM establishment by expressing CMT3 in a species naturally lacking CMT3. CMT3 expression reconstituted gbM through a progression of de novo CHG methylation on expressed genes, followed by the accumulation of CG methylation that could be inherited even following loss of the CMT3 transgene. Thus, gbM likely originates from the simultaneous targeting of loci by pathways that promote euchromatin and heterochromatin, which primes genes for the formation of stably inherited epimutations in the form of CG DNA methylation.
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Affiliation(s)
- Jered M Wendte
- Department of Genetics, University of Georgia, Athens, United States
| | - Yinwen Zhang
- Institute of Bioinformatics, University of Georgia, Athens, United States
| | - Lexiang Ji
- Institute of Bioinformatics, University of Georgia, Athens, United States
| | - Xiuling Shi
- Department of Genetics, University of Georgia, Athens, United States
| | - Rashmi R Hazarika
- Department of Plant Science, Technical University of Munich, Freising, Germany
| | - Yadollah Shahryary
- Department of Plant Science, Technical University of Munich, Freising, Germany
| | - Frank Johannes
- Department of Plant Science, Technical University of Munich, Freising, Germany
- Institute for Advanced Study, Technical University of Munich, Garching, Germany
| | - Robert J Schmitz
- Department of Genetics, University of Georgia, Athens, United States
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168
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Epigenetic Abnormalities in Acute Myeloid Leukemia and Leukemia Stem Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019. [PMID: 31338820 DOI: 10.1007/978-981-13-7342-8_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/28/2023]
Abstract
Recently advances in cancer genomics revealed the unexpected high frequencies of epigenetic abnormalities in human acute myeloid leukemia (AML). Accumulating data suggest that these leukemia-associated epigenetic factors play critical roles in both normal hematopoietic stem cells (HSCs) and leukemia stem cells (LSCs). In turn, these abnormalities result in susceptibilities of LSC and related diseases to epigenetic inhibitors. In this chapter, we will focus on the mutations of epigenetic factors in AML, their functional roles and mechanisms in normal hematopoiesis and leukemia genesis, especially in LSC, and potential treatment opportunities specifically for AML with epigenetic dysregulations.
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169
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Liu XS, Feng SJ, Zhang BQ, Wang MQ, Cao HW, Rono JK, Chen X, Yang ZM. OsZIP1 functions as a metal efflux transporter limiting excess zinc, copper and cadmium accumulation in rice. BMC PLANT BIOLOGY 2019; 19:283. [PMID: 31248369 PMCID: PMC6598308 DOI: 10.1186/s12870-019-1899-3] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 06/19/2019] [Indexed: 05/20/2023]
Abstract
BACKGROUND Metal homeostasis is critical for plant growth, development and adaptation to environmental stresses and largely governed by a variety of metal transporters. The plant ZIP (Zn-regulated transporter, Iron-regulated transporter-like Protein) family proteins belong to the integral membrane transporters responsible for uptake and allocation of essential and non-essential metals. However, whether the ZIP family members mediate metal efflux and its regulatory mechanism remains unknown. RESULTS In this report, we provided evidence that OsZIP1 is a metal-detoxified transporter through preventing excess Zn, Cu and Cd accumulation in rice. OsZIP1 is abundantly expressed in roots throughout the life span and sufficiently induced by excess Zn, Cu and Cd but not by Mn and Fe at transcriptional and translational levels. Expression of OsZIP-GFP fusion in rice protoplasts and tobacco leaves shows that OsZIP1 resides in the endoplasmic reticulum (ER) and plasma membrane (PM). The yeast (Saccharomyces cerevisiae) complementation test shows that expression of OsZIP1 reduced Zn accumulation. Transgenic rice overexpressing OsZIP1 grew better under excess metal stress but accumulated less of the metals in plants. In contrast, both oszip1 mutant and RNA interference (RNAi) lines accumulated more metal in roots and contributed to metal sensitive phenotypes. These results suggest OsZIP1 is able to function as a metal exporter in rice when Zn, Cu and Cd are excess in environment. We further identified the DNA methylation of histone H3K9me2 of OsZIP1 and found that OsZIP1 locus, whose transcribed regions imbed a 242 bp sequence, is demethylated, suggesting that epigenetic modification is likely associated with OsZIP1 function under Cd stress. CONCLUSION OsZIP1 is a transporter that is required for detoxification of excess Zn, Cu and Cd in rice.
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Affiliation(s)
- Xue Song Liu
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
| | - Sheng Jun Feng
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
- Zhejiang Provincial Key Laboratory of Bioremediation of Soil Contamination, Laboratory of Plant Molecular and Developmental Biology, Zhejiang Agriculture & Forestry University, Hangzhou, 311300 China
| | - Bai Qing Zhang
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
| | - Meng Qi Wang
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
| | - Hong Wei Cao
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
| | - Justice Kipkoir Rono
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
| | - Xi Chen
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
| | - Zhi Min Yang
- Department of Biochemistry and Molecular Biology, College of Life Science, Nanjing Agricultural University, Nanjing, 210095 China
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170
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Long JC, Xia AA, Liu JH, Jing JL, Wang YZ, Qi CY, He Y. Decrease in DNA methylation 1 (DDM1) is required for the formation of m CHH islands in maize. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2019; 61:749-764. [PMID: 30387549 DOI: 10.1111/jipb.12733] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/23/2018] [Indexed: 05/26/2023]
Abstract
DNA methylation plays a crucial role in suppressing mobilization of transposable elements and regulation of gene expression. A number of studies have indicated that DNA methylation pathways and patterns exhibit distinct properties in different species, including Arabidopsis, rice, and maize. Here, we characterized the function of DDM1 in regulating genome-wide DNA methylation in maize. Two homologs of ZmDDM1 are abundantly expressed in the embryo and their simultaneous disruption caused embryo lethality with abnormalities in cell proliferation from the early stage of kernel development. We establish that ZmDDM1 is critical for DNA methylation, at CHG sites, and to a lesser extent at CG sites, in heterochromatic regions, and unexpectedly, it is required for the formation of m CHH islands. In addition, ZmDDM1 is indispensable for the presence of 24-nt siRNA, suggesting its involvement in the RdDM pathway. Our results provide novel insight into the role of ZmDDM1 in regulating the formation of m CHH islands, via the RdDM pathway maize, suggesting that, in comparison to Arabidopsis, maize may have adopted distinct mechanisms for regulating m CHH.
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Affiliation(s)
- Jin Cheng Long
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Ai Ai Xia
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Jing Han Liu
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Ju Li Jing
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Ya Zhong Wang
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Chuang Ye Qi
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
| | - Yan He
- National Maize Improvement Center of China, China Agricultural University, Beijing 100094, China
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171
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Kawakatsu T, Ecker JR. Diversity and dynamics of DNA methylation: epigenomic resources and tools for crop breeding. BREEDING SCIENCE 2019; 69:191-204. [PMID: 31481828 PMCID: PMC6711733 DOI: 10.1270/jsbbs.19005] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/18/2019] [Indexed: 05/17/2023]
Abstract
DNA methylation is an epigenetic modification that can affect gene expression and transposable element (TE) activities. Because cytosine DNA methylation patterns are inherited through both mitotic and meiotic cell divisions, differences in these patterns can contribute to phenotypic variability. Advances in high-throughput sequencing technologies have enabled the generation of abundant DNA sequence data. Integrated analyses of genome-wide gene expression patterns and DNA methylation patterns have revealed the underlying mechanisms and functions of DNA methylation. Moreover, associations between DNA methylation and agronomic traits have also been uncovered. The resulting information may be useful for future applications of natural epigenomic variation, for crop breeding. Additionally, artificial epigenome editing may be an attractive new plant breeding technique for generating novel varieties with improved agronomic traits.
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Affiliation(s)
- Taiji Kawakatsu
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization,
1-2 Owashi Tsukuba, Ibaraki 305-8634,
Japan
- Corresponding author (e-mail: )
| | - Joseph R. Ecker
- Howard Hughes Medical Institute,
10010 North Torrey Pines Road, La Jolla, CA 92037,
USA
- The Salk Institute for Biological Studies,
10010 North Torrey Pines Road, La Jolla, CA 92037,
USA
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172
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You WJ, Feng YR, Shen YH, Chen YR, Chen TY, Fu SF. Silencing of NbCMT3s has Pleiotropic Effects on Development by Interfering with Autophagy-Related Genes in Nicotiana benthamiana. PLANT & CELL PHYSIOLOGY 2019; 60:1120-1135. [PMID: 30785195 DOI: 10.1093/pcp/pcz034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 02/14/2019] [Indexed: 05/25/2023]
Abstract
DNA methylation is a chromatin mark that has a crucial role in regulating gene expression. The chromomethylase (CMT) protein family is a plant-specific DNA methyltransferase that mediates growth and development. However, the roles of CMT3 in autophagy remain to be elucidated. Here, we identified the potential targets of CMT3 in Nicotiana benthamiana (NbCMT3) during developmental programs. Virus-induced gene silencing of NbCMT3/3-2 in N. benthamiana had pleiotropic effects on plant morphology, which indicates its indispensible role in development. Genome-wide transcriptome analysis of NbCMT3/3-2-silenced plants revealed interference with genes related to autophagy and ubiquitination. The expression of NbBeclin 1 and NbHRD1B was higher in NbCMT3/3-2-silenced than control plants. The formation of autophagosomes and starch degradation was disrupted in NbCMT3/3-2-silenced plants, which implies a perturbed autophagic processes. We further generated transgenic N. benthamiana plants carrying a chimeric promoter-reporter construct linking the NbBeclin 1 promoter region and β-glucuronidase (GUS) reporter (pNbBeclin::GUS). NbBeclin 1 promoter activity was significantly enhanced in NbCMT3/3-2-silenced plants. Thus, NbCMT3/3-2 silencing had pleiotropic effects on development by interfering with NbBeclin 1 expression and autophagy-related processes.
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Affiliation(s)
- Wen-Jing You
- Department of Biology, National Changhua University of Education, No.1, Jin-De Road, Changhua, Taiwan
| | - Yun-Ru Feng
- Department of Biology, National Changhua University of Education, No.1, Jin-De Road, Changhua, Taiwan
| | - Ya-Han Shen
- Department of Biology, National Changhua University of Education, No.1, Jin-De Road, Changhua, Taiwan
| | - Yi-Ru Chen
- Department of Biology, National Changhua University of Education, No.1, Jin-De Road, Changhua, Taiwan
| | - Tzy-Yi Chen
- Department of Biology, National Changhua University of Education, No.1, Jin-De Road, Changhua, Taiwan
| | - Shih-Feng Fu
- Department of Biology, National Changhua University of Education, No.1, Jin-De Road, Changhua, Taiwan
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173
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Shafi A, Mitrea C, Nguyen T, Draghici S. A survey of the approaches for identifying differential methylation using bisulfite sequencing data. Brief Bioinform 2019; 19:737-753. [PMID: 28334228 DOI: 10.1093/bib/bbx013] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Indexed: 01/03/2023] Open
Abstract
DNA methylation is an important epigenetic mechanism that plays a crucial role in cellular regulatory systems. Recent advancements in sequencing technologies now enable us to generate high-throughput methylation data and to measure methylation up to single-base resolution. This wealth of data does not come without challenges, and one of the key challenges in DNA methylation studies is to identify the significant differences in the methylation levels of the base pairs across distinct biological conditions. Several computational methods have been developed to identify differential methylation using bisulfite sequencing data; however, there is no clear consensus among existing approaches. A comprehensive survey of these approaches would be of great benefit to potential users and researchers to get a complete picture of the available resources. In this article, we present a detailed survey of 22 such approaches focusing on their underlying statistical models, primary features, key advantages and major limitations. Importantly, the intrinsic drawbacks of the approaches pointed out in this survey could potentially be addressed by future research.
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Affiliation(s)
- Adib Shafi
- Department of Computer Science, Wayne State University, USA
| | | | - Tin Nguyen
- Department of Computer Science, Wayne State University, USA
| | - Sorin Draghici
- Department of Computer Science, Wayne State University, USA.,Department of Obstetrics and Gynecology, Wayne State University, USA
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174
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Wang L, Shi Y, Chang X, Jing S, Zhang Q, You C, Yuan H, Wang H. DNA methylome analysis provides evidence that the expansion of the tea genome is linked to TE bursts. PLANT BIOTECHNOLOGY JOURNAL 2019; 17:826-835. [PMID: 30256509 PMCID: PMC6419580 DOI: 10.1111/pbi.13018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/14/2018] [Accepted: 09/23/2018] [Indexed: 05/12/2023]
Abstract
DNA methylation is essential for gene regulation, imprinting and silencing of transposable elements (TEs). Although bursts of transposable elements are common in many plant lineages, how plant DNA methylation is related to transposon bursts remains unclear. Here we explore the landscape of DNA methylation of tea, a species thought to have experienced a recent transposon burst event. This species possesses more transposable elements than any other sequenced asterids (potato, tomato, coffee, pepper and tobacco). The overall average DNA methylation levels were found to differ among the tea, potato and tomato genomes, and methylation at CHG sequence sites was found to be significantly higher in tea than that in potato or tomato. Moreover, the abundant TEs resulting from burst events not only resulted in tea developing a very large genome size, but also affected many genes involved in importantly biological processes, including caffeine, theanine and flavonoid metabolic pathway genes. In addition, recently transposed TEs were more heavily methylated than ancient ones, implying that DNA methylation is proportionate to the degree of TE silencing, especially on recent active ones. Taken together, our results show that DNA methylation regulates transposon silencing and may play a role in genome size expansion.
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Affiliation(s)
- Lei Wang
- Henan Key Laboratory of Tea Plant BiologyCollege of Life ScienceXinyang Normal UniversityXinyangChina
| | - Yan Shi
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsCollege of Plant ProtectionFujian Agriculture and Forestry UniversityFuzhouChina
| | - Xiaojun Chang
- College of HorticultureFujian Agriculture and Forestry UniversityFuzhouChina
| | - Shengli Jing
- Henan Key Laboratory of Tea Plant BiologyCollege of Life ScienceXinyang Normal UniversityXinyangChina
| | - Qunjie Zhang
- Agrobiological Gene Research CenterGuangdong Academy of Agricultural SciencesGuangzhouChina
| | - Chenjiang You
- Guangdong Provincial Key Laboratory of Plant EpigeneticsCollege of Life Sciences and OceanographyShenzhen UniversityShenzhenChina
- Department of Botany and Plant SciencesInstitute of Integrative Genome BiologyUniversity of CaliforniaRiversideCAUSA
| | - Hongyu Yuan
- Henan Key Laboratory of Tea Plant BiologyCollege of Life ScienceXinyang Normal UniversityXinyangChina
| | - Haifeng Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan CropsCollege of Plant ProtectionFujian Agriculture and Forestry UniversityFuzhouChina
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175
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Abstract
Circadian rhythms in transcription ultimately result in oscillations of key biological processes. Understanding how transcriptional rhythms are generated in plants provides an opportunity for fine-tuning growth, development, and responses to the environment. Here, we present a succinct description of the plant circadian clock, briefly reviewing a number of recent studies but mostly emphasizing the components and mechanisms connecting chromatin remodeling with transcriptional regulation by the clock. The possibility that intergenomic interactions govern hybrid vigor through epigenetic changes at clock loci and the function of epialleles controlling clock output traits during crop domestication are also discussed.
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Affiliation(s)
- Z Jeffrey Chen
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA.,Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Paloma Mas
- Center for Research in Agricultural Genomics (CRAG), Consortium CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, 08193, Barcelona, Spain. .,Consejo Superior de Investigaciones Científicas, 08028, Barcelona, Spain.
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176
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Forgione I, Wołoszyńska M, Pacenza M, Chiappetta A, Greco M, Araniti F, Abenavoli MR, Van Lijsebettens M, Bitonti MB, Bruno L. Hypomethylated drm1 drm2 cmt3 mutant phenotype of Arabidopsis thaliana is related to auxin pathway impairment. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 280:383-396. [PMID: 30824017 DOI: 10.1016/j.plantsci.2018.12.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/27/2018] [Accepted: 12/29/2018] [Indexed: 05/28/2023]
Abstract
DNA methylation carried out by different methyltransferase classes is a relevant epigenetic modification of DNA which plays a relevant role in the development of eukaryotic organisms. Accordingly, in Arabidopsis thaliana loss of DNA methylation due to combined mutations in genes encoding for DNA methyltransferases causes several developmental abnormalities. The present study describes novel growth disorders in the drm1 drm2 cmt3 triple mutant of Arabidopsis thaliana, defective both in maintenance and de novo DNA methylation, and highlights the correlation between DNA methylation and the auxin hormone pathway. By using an auxin responsive reporter gene, we discovered that auxin accumulation and distribution were affected in the mutant compared to the wild type, from embryo to adult plant stage. In addition, we demonstrated that the defective methylation status also affected the expression of genes that regulate auxin hormone pathways from synthesis to transport and signalling and a direct relationship between differentially expressed auxin-related genes and altered auxin accumulation and distribution in embryo, leaf and root was observed. Finally, we provided evidence of the direct and organ-specific modulation of auxin-related genes through the DNA methylation process.
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Affiliation(s)
- Ivano Forgione
- Dipartimento di Biologia, Ecologia e Scienze della Terra, Università della Calabria, Arcavacata di Rende (CS), 87036 Arcavacata di Rende, CS, Italy; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Magdalena Wołoszyńska
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Marianna Pacenza
- Dipartimento di Biologia, Ecologia e Scienze della Terra, Università della Calabria, Arcavacata di Rende (CS), 87036 Arcavacata di Rende, CS, Italy
| | - Adriana Chiappetta
- Dipartimento di Biologia, Ecologia e Scienze della Terra, Università della Calabria, Arcavacata di Rende (CS), 87036 Arcavacata di Rende, CS, Italy
| | - Maria Greco
- Dipartimento di Biologia, Ecologia e Scienze della Terra, Università della Calabria, Arcavacata di Rende (CS), 87036 Arcavacata di Rende, CS, Italy; The Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Fabrizio Araniti
- Dipartimento di Agraria, Università Mediterranea di Reggio Calabria, 89124 Reggio Calabria, Italy
| | - Maria Rosa Abenavoli
- Dipartimento di Agraria, Università Mediterranea di Reggio Calabria, 89124 Reggio Calabria, Italy
| | - Mieke Van Lijsebettens
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Maria Beatrice Bitonti
- Dipartimento di Biologia, Ecologia e Scienze della Terra, Università della Calabria, Arcavacata di Rende (CS), 87036 Arcavacata di Rende, CS, Italy
| | - Leonardo Bruno
- Dipartimento di Biologia, Ecologia e Scienze della Terra, Università della Calabria, Arcavacata di Rende (CS), 87036 Arcavacata di Rende, CS, Italy.
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177
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Genome defense against integrated organellar DNA fragments from plastids into plant nuclear genomes through DNA methylation. Sci Rep 2019; 9:2060. [PMID: 30765781 PMCID: PMC6376042 DOI: 10.1038/s41598-019-38607-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 12/31/2018] [Indexed: 01/09/2023] Open
Abstract
Nuclear genomes are always faced with the modification of themselves by insertions and integrations of foreign DNAs and intrinsic parasites such as transposable elements. There is also substantial number of integrations from symbiotic organellar genomes to their host nuclear genomes. Such integration might have acted as a beneficial mutation during the evolution of symbiosis, while most of them have more or less deleterious effects on the stability of current genomes. Here we report the pattern of DNA substitution and methylation on organellar DNA fragments integrated from plastid into plant nuclear genomes. The genome analyses of 17 plants show homology–dependent DNA substitution bias. A certain number of these sequences are DNA methylated in the nuclear genome. The intensity of DNA methylation also decays according to the increase of relative evolutionary times after being integrated into nuclear genomes. The methylome data of epigenetic mutants shows that the DNA methylation of organellar DNA fragments in nuclear genomes are mainly dependent on the methylation maintenance machinery, while other mechanisms may also affect on the DNA methylation level. The DNA methylation on organellar DNA fragments may contribute to maintaining the genome stability and evolutionary dynamics of symbiotic organellar and their host’s genomes.
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178
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Xiao X, Zhang J, Li T, Fu X, Satheesh V, Niu Q, Lang Z, Zhu JK, Lei M. A group of SUVH methyl-DNA binding proteins regulate expression of the DNA demethylase ROS1 in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2019; 61:110-119. [PMID: 30589237 DOI: 10.1111/jipb.12768] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 12/25/2018] [Indexed: 05/22/2023]
Abstract
DNA methylation is typically regarded as a repressive epigenetic marker for gene expression. Genome-wide DNA methylation patterns in plants are dynamically regulated by the opposing activities of DNA methylation and demethylation reactions. In Arabidopsis, a DNA methylation monitoring sequence (MEMS) in the promoter of the DNA demethylase gene ROS1 functions as a methylstat that senses these opposing activities and regulates genome DNA methylation levels by adjusting ROS1 expression. How DNA methylation in the MEMS region promotes ROS1 expression is not known. Here, we show that several Su(var)3-9 homologs (SUVHs) can sense DNA methylation levels at the MEMS region and function redundantly to promote ROS1 expression. The SUVHs bind to the MEMS region, and the extent of binding is correlated with the methylation level of the MEMS. Mutations in the SUVHs lead to decreased ROS1 expression, causing DNA hypermethylation at more than 1,000 genomic regions. Thus, the SUVHs function to mediate the activation of gene transcription by DNA methylation.
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Affiliation(s)
- Xinlong Xiao
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jieqiong Zhang
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
- The University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tao Li
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
- The University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xing Fu
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Viswanathan Satheesh
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Qingfeng Niu
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhaobo Lang
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette 47907, USA
| | - Mingguang Lei
- Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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179
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Wang Q, Liu S, Lu C, La Y, Dai J, Ma H, Zhou S, Tan F, Wang X, Wu Y, Kong W, La H. Roles of CRWN-family proteins in protecting genomic DNA against oxidative damage. JOURNAL OF PLANT PHYSIOLOGY 2019; 233:20-30. [PMID: 30576929 DOI: 10.1016/j.jplph.2018.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 05/22/2023]
Abstract
CROWDED NUCLEI (CRWN) family in Arabidopsis consists of four members, CRWN1 to CRWN4. It has been previously reported that the CRWN proteins are involved in the control of nuclear morphology and degradation of ABI5. In this study, however, we discover that CRWN-family proteins are not only involved in attenuating responsiveness to abscisic acid (ABA), but also implicated in inhibiting reactive oxygen species (ROS) production and DNA damage induced by genotoxic agent methyl methanesulfonate (MMS). Our results demonstrate that three crwn double mutants, i.e. crwn1 crwn3, crwn2 crwn3, and crwn2 crwn4, show slightly earlier leaf senescence, enhanced leaf cell death, and obvious overaccumulation of ROS under regular growth conditions. When treated with 0.15 μM ABA or 0.01% MMS, two double mutants, crwn1 crwn3 and crwn2 crwn3, exhibit significant decreased germination rates as well as leaf opening and greening rates. Moreover, subsequent investigations indicate that the MMS treatment strongly inhibits the growth of crwn mutant seedlings, while this inhibition is substantially relieved by imidazole (IMZ); by contrast, DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) has no effect on relief of the growth inhibition. Further studies reveal that under 0.01% MMS treatment conditions, crwn mutants, especially the three double mutants, accumulate more ROS compared to Col-0, and their genomic DNA suffers from more severe DNA damage relative to Col-0, which is indicated by significantly higher 8-oxo-7-hydrodeoxyguanosine (8-oxo dG) content as observed in the crwn mutants. Altogether, these data clearly demonstrate that the CRWN-family proteins play important roles in diminishing ROS accumulation and protecting genomic DNA against excessive oxidative damage caused by MMS.
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Affiliation(s)
- Qianqian Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Shuai Liu
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Chong Lu
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Yumei La
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Jie Dai
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Hongyu Ma
- College of Plant Protection, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Shaoxia Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Feng Tan
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Xiangyu Wang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Yufeng Wu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Bioinformatics Center, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China
| | - Weiwen Kong
- School of Horticulture and Plant Protection, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Honggui La
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
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180
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Global increase in DNA methylation during orange fruit development and ripening. Proc Natl Acad Sci U S A 2019; 116:1430-1436. [PMID: 30635417 DOI: 10.1073/pnas.1815441116] [Citation(s) in RCA: 136] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA methylation is an important epigenetic mark involved in many biological processes. The genome of the climacteric tomato fruit undergoes a global loss of DNA methylation due to active DNA demethylation during the ripening process. It is unclear whether the ripening of other fruits is also associated with global DNA demethylation. We characterized the single-base resolution DNA methylomes of sweet orange fruits. Compared with immature orange fruits, ripe orange fruits gained DNA methylation at over 30,000 genomic regions and lost DNA methylation at about 1,000 genomic regions, suggesting a global increase in DNA methylation during orange fruit ripening. This increase in DNA methylation was correlated with decreased expression of DNA demethylase genes. The application of a DNA methylation inhibitor interfered with ripening, indicating that the DNA hypermethylation is critical for the proper ripening of orange fruits. We found that ripening-associated DNA hypermethylation was associated with the repression of several hundred genes, such as photosynthesis genes, and with the activation of hundreds of genes, including genes involved in abscisic acid responses. Our results suggest important roles of DNA methylation in orange fruit ripening.
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181
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Roy Choudhury S. Genome-wide alterations of epigenomic landscape in plants by engineered nanomaterial toxicants. COMPREHENSIVE ANALYTICAL CHEMISTRY 2019. [DOI: 10.1016/bs.coac.2019.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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182
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Abstract
Plants, when challenged with any unfavorable condition, such as biotic or abiotic stress, adapt to the stress via physiological or structural changes. DNA methylation, an important epigenetic factor, plays an integral role in determining chromatin dynamicity and in turn regulates the process of gene transcription in eukaryotes. DNA methylation resulting in 5-methylcytosine interferes with the transcription process by hindering accessibility of the transcriptional machinery. Transcriptionally active genes are predominantly hypomethylated, whereas repressed genes exhibit hypermethylation. It can thus be interpreted that the presence of methylation in the promoter and upstream regions of loci represses their transcription and vice versa. Chop-PCR is a targeted DNA methylation detection technique that uses partial digestion by methylation-sensitive restriction enzymes (MSREs) followed by PCR amplification. The presence of cytosine methylation at the cleavage sites of the MSREs protects the DNA against digestion and therefore can be amplified using PCR. Enzymatic cleavage occurs unhindered at unmethylated restriction sites and subsequent PCR amplification of the target sequence is not observed.
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183
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Geng S, Kong X, Song G, Jia M, Guan J, Wang F, Qin Z, Wu L, Lan X, Li A, Mao L. DNA methylation dynamics during the interaction of wheat progenitor Aegilops tauschii with the obligate biotrophic fungus Blumeria graminis f. sp. tritici. THE NEW PHYTOLOGIST 2019; 221:1023-1035. [PMID: 30256420 PMCID: PMC6586159 DOI: 10.1111/nph.15432] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 08/06/2018] [Indexed: 05/23/2023]
Abstract
DNA methylation is dynamically involved in plant immunity, but little information is known about its roles in plant interactions with biotrophic fungi, especially in temperate grasses such as wheat (Triticum aestivum). Using wheat diploid progenitor Aegilops tauschii accession AL8/78, the genome of which has been sequenced, we assessed the extent of DNA methylation in response to infection with Blumeria graminis f. sp. tritici (Bgt), which causes powdery mildew. Upon Bgt infection, ARGONAUTE4a (AGO4a) was significantly downregulated in A. tauschii, which was accompanied by a substantial reduction in AGO4a-sorted 24-nt siRNA levels, especially for genes near transposable elements (TAGs). Bisulfite sequencing revealed abundant differentially methylated regions (DMRs) with CHH hypomethylation. TAGs bearing CHH-hypomethylated DMRs were enriched for 'response to stress' functions, including receptor kinase, peroxidase, and pathogenesis-related genes. Virus-induced gene silencing (VIGS) of a DOMAINS REARRANGED METHYLASE 2 (DRM2) homolog enhanced plant resistance to Bgt. The effect of CHH hypomethylation was exemplified by the upregulation of a pathogenesis-related β-1,3-glucanse gene implicated in Bgt defense. These findings support the idea that dynamic DNA methylation represents a regulatory layer in the complex mechanism of plant immunity, which could be exploited to improve disease resistance in common wheat.
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Affiliation(s)
- Shuaifeng Geng
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijing100081China
| | - Xingchen Kong
- Triticeae Research InstituteSichuan Agricultural UniversityChengduSichuan611130China
| | - Gaoyuan Song
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijing100081China
| | - Meiling Jia
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijing100081China
| | - Jiantao Guan
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijing100081China
| | - Fang Wang
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijing100081China
| | - Zhengrui Qin
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhou310058China
| | - Liang Wu
- Department of AgronomyCollege of Agriculture and BiotechnologyZhejiang UniversityHangzhou310058China
| | - Xiujin Lan
- Triticeae Research InstituteSichuan Agricultural UniversityChengduSichuan611130China
| | - Aili Li
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijing100081China
| | - Long Mao
- National Key Facility for Crop Gene Resources and Genetic ImprovementInstitute of Crop ScienceChinese Academy of Agricultural SciencesBeijing100081China
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184
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Dluzewska J, Szymanska M, Ziolkowski PA. Where to Cross Over? Defining Crossover Sites in Plants. Front Genet 2018; 9:609. [PMID: 30619450 PMCID: PMC6299014 DOI: 10.3389/fgene.2018.00609] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/19/2018] [Indexed: 12/16/2022] Open
Abstract
It is believed that recombination in meiosis serves to reshuffle genetic material from both parents to increase genetic variation in the progeny. At the same time, the number of crossovers is usually kept at a very low level. As a consequence, many organisms need to make the best possible use from the one or two crossovers that occur per chromosome in meiosis. From this perspective, the decision of where to allocate rare crossover events becomes an important issue, especially in self-pollinating plant species, which experience limited variation due to inbreeding. However, the freedom in crossover allocation is significantly limited by other, genetic and non-genetic factors, including chromatin structure. Here we summarize recent progress in our understanding of those processes with a special emphasis on plant genomes. First, we focus on factors which influence the distribution of recombination initiation sites and discuss their effects at both, the single hotspot level and at the chromosome scale. We also briefly explain the aspects of hotspot evolution and their regulation. Next, we analyze how recombination initiation sites translate into the development of crossovers and their location. Moreover, we provide an overview of the sequence polymorphism impact on crossover formation and chromosomal distribution.
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Affiliation(s)
- Julia Dluzewska
- Department of Genome Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznań, Poland
| | - Maja Szymanska
- Department of Genome Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznań, Poland
| | - Piotr A Ziolkowski
- Department of Genome Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznań, Poland
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185
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Yadav NS, Khadka J, Domb K, Zemach A, Grafi G. CMT3 and SUVH4/KYP silence the exonic Evelknievel retroelement to allow for reconstitution of CMT1 mRNA. Epigenetics Chromatin 2018; 11:69. [PMID: 30446008 PMCID: PMC6238269 DOI: 10.1186/s13072-018-0240-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 11/09/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The Chromomethylase 1 (CMT1) has long been considered a nonessential gene because, in certain Arabidopsis ecotypes, the CMT1 gene is disrupted by the Evelknievel (EK) retroelement, inserted within exon 13, or contains frameshift mutations, resulting in a truncated, non-functional protein. In contrast to other transposable elements, no transcriptional activation of EK was observed under stress conditions (e.g., protoplasting). RESULTS We wanted to explore the regulatory pathway responsible for EK silencing in the Ler ecotype and its effect on CMT1 transcription. Methylome databases confirmed that EK retroelement is heavily methylated and methylation is extended toward CMT1 downstream region. Strong transcriptional activation of EK accompanied by significant reduction in non-CG methylation was found in cmt3 and kyp2, but not in ddm1 or RdDM mutants. EK activation in cmt3 and kyp2 did not interfere with upstream CMT1 expression but abolish transcription through the EK. We identified, in wild-type Ler, three spliced variants in which the entire EK is spliced out; one variant (25% of splicing incidents) facilitates proper reconstitution of an intact CMT1 mRNA. We could recover very low amount of the full-length CMT1 mRNA from WT Ler and Col, but not from cmt3 mutant. CONCLUSIONS Our findings highlight CMT3-SUVH4/KYP as the major pathway silencing the intragenic EK via inducing non-CG methylation. Furthermore, retroelement insertion within exons (e.g., CMT1) may not lead to a complete abolishment of the gene product when the element is kept silent. Rather the element can be spliced out to bring about reconstruction of an intact, functional mRNA and possibly retrieval of an active protein.
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Affiliation(s)
- Narendra Singh Yadav
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990, Midreshet Ben Gurion, Israel
| | - Janardan Khadka
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990, Midreshet Ben Gurion, Israel
| | - Katherine Domb
- The School of Plant Sciences and Food Security, Tel-Aviv University, 69978, Tel Aviv, Israel
| | - Assaf Zemach
- The School of Plant Sciences and Food Security, Tel-Aviv University, 69978, Tel Aviv, Israel
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990, Midreshet Ben Gurion, Israel.
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186
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Stoddard CI, Feng S, Campbell MG, Liu W, Wang H, Zhong X, Bernatavichute Y, Cheng Y, Jacobsen SE, Narlikar GJ. A Nucleosome Bridging Mechanism for Activation of a Maintenance DNA Methyltransferase. Mol Cell 2018; 73:73-83.e6. [PMID: 30415948 DOI: 10.1016/j.molcel.2018.10.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 08/22/2018] [Accepted: 10/01/2018] [Indexed: 12/12/2022]
Abstract
DNA methylation and H3K9me are hallmarks of heterochromatin in plants and mammals, and are successfully maintained across generations. The biochemical and structural basis for this maintenance is poorly understood. The maintenance DNA methyltransferase from Zea mays, ZMET2, recognizes dimethylation of H3K9 via a chromodomain (CD) and a bromo adjacent homology (BAH) domain, which flank the catalytic domain. Here, we show that dinucleosomes are the preferred ZMET2 substrate, with DNA methylation preferentially targeted to linker DNA. Electron microscopy shows one ZMET2 molecule bridging two nucleosomes within a dinucleosome. We find that the CD stabilizes binding, whereas the BAH domain enables allosteric activation by the H3K9me mark. ZMET2 further couples recognition of H3K9me to an increase in the specificity for hemimethylated versus unmethylated DNA. We propose a model in which synergistic coupling between recognition of nucleosome spacing, H3K9 methylation, and DNA modification allows ZMET2 to maintain DNA methylation in heterochromatin with high fidelity.
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Affiliation(s)
- Caitlin I Stoddard
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Suhua Feng
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Melody G Campbell
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Wanlu Liu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Haifeng Wang
- Basic Forestry and Proteomics Research Center, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China; Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xuehua Zhong
- Laboratory of Genetics & Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Yana Bernatavichute
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Steven E Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA 90095, USA; Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Geeta J Narlikar
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA.
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187
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Thibaut O, Claude B. Innate Immunity Activation and RNAi Interplay in Citrus Exocortis Viroid-Tomato Pathosystem. Viruses 2018; 10:E587. [PMID: 30373191 PMCID: PMC6266551 DOI: 10.3390/v10110587] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Revised: 10/18/2018] [Accepted: 10/24/2018] [Indexed: 12/21/2022] Open
Abstract
Although viroids are the smallest and simplest plant pathogens known, the molecular mechanisms underlying their pathogenesis remain unclear. To unravel these mechanisms, a dual approach was implemented consisting of in silico identification of potential tomato silencing targets of pospiviroids, and the experimental validation of these targets through the sequencing of small RNAs and RNA ends extracted from tomatoes infected with a severe isolate of Citrus exocortis viroid (CEVd). The generated RNA ends were also used to monitor the differentially-expressed genes. These analyses showed that when CEVd symptoms are well established: (i) CEVd are degraded by at least three Dicer-like (DCL) proteins and possibly by RNA-induced silencing complex (RISC), (ii) five different mRNAs are partially degraded through post-transcriptional gene silencing (PTGS), including argonaute 2a, which is further degraded in phasiRNAs, (iii) Dicer-like 2b and 2d are both upregulated and degraded in phasiRNAs, and (iv) CEVd infection induced a significant shift in gene expression allowing to explain the usual symptoms of pospiviroids on tomato and to demonstrate the constant activation of host innate immunity and systemic acquired resistance (SAR) by these pathogenic RNAs. Finally, based on in silico analysis, potential immunity receptor candidates of viroid-derived RNAs are suggested.
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Affiliation(s)
- Olivier Thibaut
- Life Sciences Department, Walloon agricultural research Centre, Rue de Liroux 4, 5030 Gembloux, Belgium.
- UCLouvain, Earth&Life Institute, Croix du Sud 2bte L7.05.03, 1348 Louvain-la-Neuve, Belgium.
| | - Bragard Claude
- UCLouvain, Earth&Life Institute, Croix du Sud 2bte L7.05.03, 1348 Louvain-la-Neuve, Belgium.
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188
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Osorio-Montalvo P, Sáenz-Carbonell L, De-la-Peña C. 5-Azacytidine: A Promoter of Epigenetic Changes in the Quest to Improve Plant Somatic Embryogenesis. Int J Mol Sci 2018; 19:E3182. [PMID: 30332727 PMCID: PMC6214027 DOI: 10.3390/ijms19103182] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 02/06/2023] Open
Abstract
Somatic embryogenesis (SE) is a widely studied process due to its biotechnological potential to generate large quantities of plants in short time frames and from different sources of explants. The success of SE depends on many factors, such as the nature of the explant, the microenvironment generated by in vitro culture conditions, and the regulation of gene expression, among others. Epigenetics has recently been identified as an important factor influencing SE outcome. DNA methylation is one of the most studied epigenetic mechanisms due to its essential role in gene expression, and its participation in SE is crucial. DNA methylation levels can be modified through the use of drugs such as 5-Azacytidine (5-AzaC), an inhibitor of DNA methylation, which has been used during SE protocols. The balance between hypomethylation and hypermethylation seems to be the key to SE success. Here, we discuss the most prominent recent research on the role of 5-AzaC in the regulation of DNA methylation, highlighting its importance during the SE process. Also, the molecular implications that this inhibitor might have for the increase or decrease in the embryogenic potential of various explants are reviewed.
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Affiliation(s)
- Pedro Osorio-Montalvo
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Calle 43 No. 130 x 32 y 34, Col. Chuburná de Hidalgo, 97205 Mérida, Yucatán, Mexico.
| | - Luis Sáenz-Carbonell
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Calle 43 No. 130 x 32 y 34, Col. Chuburná de Hidalgo, 97205 Mérida, Yucatán, Mexico.
| | - Clelia De-la-Peña
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, Calle 43 No. 130 x 32 y 34, Col. Chuburná de Hidalgo, 97205 Mérida, Yucatán, Mexico.
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Mechanistic insights into plant SUVH family H3K9 methyltransferases and their binding to context-biased non-CG DNA methylation. Proc Natl Acad Sci U S A 2018; 115:E8793-E8802. [PMID: 30150382 DOI: 10.1073/pnas.1809841115] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
DNA methylation functions in gene silencing and the maintenance of genome integrity. In plants, non-CG DNA methylation is linked through a self-reinforcing loop with histone 3 lysine 9 dimethylation (H3K9me2). The plant-specific SUPPRESSOR OF VARIEGATION 3-9 HOMOLOG (SUVH) family H3K9 methyltransferases (MTases) bind to DNA methylation marks and catalyze H3K9 methylation. Here, we analyzed the structure and function of Arabidopsis thaliana SUVH6 to understand how this class of enzyme maintains methylation patterns in the genome. We reveal that SUVH6 has a distinct 5-methyl-dC (5mC) base-flipping mechanism involving a thumb loop element. Autoinhibition of H3 substrate entry is regulated by a SET domain loop, and a conformational transition in the post-SET domain upon cofactor binding may control catalysis. In vitro DNA binding and in vivo ChIP-seq data reveal that the different SUVH family H3K9 MTases have distinct DNA binding preferences, targeting H3K9 methylation to sites with different methylated DNA sequences, explaining the context biased non-CG DNA methylation in plants.
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190
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Tan LM, Zhang CJ, Hou XM, Shao CR, Lu YJ, Zhou JX, Li YQ, Li L, Chen S, He XJ. The PEAT protein complexes are required for histone deacetylation and heterochromatin silencing. EMBO J 2018; 37:embj.201798770. [PMID: 30104406 DOI: 10.15252/embj.201798770] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 06/27/2018] [Accepted: 06/28/2018] [Indexed: 01/26/2023] Open
Abstract
In eukaryotes, heterochromatin regions are typically subjected to transcriptional silencing. DNA methylation has an important role in such silencing and has been studied extensively. However, little is known about how methylated heterochromatin regions are subjected to silencing. We conducted a genetic screen and identified an epcr (enhancer of polycomb-related) mutant that releases heterochromatin silencing in Arabidopsis thaliana We demonstrated that EPCR1 functions redundantly with its paralog EPCR2 and interacts with PWWP domain-containing proteins (PWWPs), AT-rich interaction domain-containing proteins (ARIDs), and telomere repeat binding proteins (TRBs), thus forming multiple functionally redundant protein complexes named PEAT (PWWPs-EPCRs-ARIDs-TRBs). The PEAT complexes mediate histone deacetylation and heterochromatin condensation and thereby facilitate heterochromatin silencing. In heterochromatin regions, the production of small interfering RNAs (siRNAs) and DNA methylation is repressed by the PEAT complexes. The study reveals how histone deacetylation, heterochromatin condensation, siRNA production, and DNA methylation interplay with each other and thereby maintain heterochromatin silencing.
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Affiliation(s)
- Lian-Mei Tan
- National Institute of Biological Sciences, Beijing, China.,Graduate School of Peking Union Medical College, Beijing, China
| | - Cui-Jun Zhang
- National Institute of Biological Sciences, Beijing, China
| | - Xiao-Mei Hou
- National Institute of Biological Sciences, Beijing, China
| | | | - Yu-Jia Lu
- National Institute of Biological Sciences, Beijing, China
| | - Jin-Xing Zhou
- National Institute of Biological Sciences, Beijing, China
| | - Yong-Qiang Li
- National Institute of Biological Sciences, Beijing, China
| | - Lin Li
- National Institute of Biological Sciences, Beijing, China
| | - She Chen
- National Institute of Biological Sciences, Beijing, China
| | - Xin-Jian He
- National Institute of Biological Sciences, Beijing, China .,Graduate School of Peking Union Medical College, Beijing, China
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191
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Exploring potential roles for the interaction of MOM1 with SUMO and the SUMO E3 ligase-like protein PIAL2 in transcriptional silencing. PLoS One 2018; 13:e0202137. [PMID: 30092097 PMCID: PMC6084981 DOI: 10.1371/journal.pone.0202137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 07/28/2018] [Indexed: 11/30/2022] Open
Abstract
The CHD3-like chromatin remodeling protein MOM1 and the PIAS-type SUMO E3 ligase-like protein PIAL2 are known to interact with each other and mediate transcriptional silencing in Arabidopsis. However, it is poorly understood whether and how the interaction is involved in transcriptional silencing. Here, we demonstrate that, while the PIAL2 interaction domain (PIAL2-IND) is required for PIAL2 dimerization, MOM-PIAL2 interaction, and transcriptional silencing, a transgene fusing the wild-type MOM1 protein with the PIAL2 protein defective in PIAL2-IND can completely restore transcriptional silencing in the mom1/pial2 double mutant, demonstrating that the artificial fusion of MOM1 and PIAL2 mimics the in vivo interaction of these two proteins so that PIAL2-IND is no longer required for transcriptional silencing in the fusion protein. Further, our yeast two-hybrid assay identifies a previously unrecognized SUMO interaction motif (SIM) in the conserved MOM1 motif CMM3 and demonstrates that the SIM is responsible for the interaction of MOM1 with SUMO. Given that eukaryotic PIAS-type SUMO E3 ligases have a conserved role in chromatin regulation, the findings reported in this study may represent a conserved chromatin regulatory mechanism in higher eukaryotes.
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192
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Dutta S, Mitra M, Agarwal P, Mahapatra K, De S, Sett U, Roy S. Oxidative and genotoxic damages in plants in response to heavy metal stress and maintenance of genome stability. PLANT SIGNALING & BEHAVIOR 2018; 13:e1460048. [PMID: 29621424 PMCID: PMC6149466 DOI: 10.1080/15592324.2018.1460048] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 03/28/2018] [Indexed: 05/17/2023]
Abstract
Plants, being sessile in nature, are constantly exposed to various environmental stresses, such as solar UV radiations, soil salinity, drought and desiccation, rehydration, low and high temperatures and other vast array of air and soil borne chemicals, industrial waste products, metals and metalloids. These agents, either directly or indirectly via the induction of oxidative stress and overproduction of reactive oxygen species (ROS), frequently perturb the chemical or physical structures of DNA and induce both cytotoxic or genotoxic stresses. Such condition, in turn, leads to genome instability and thus eventually severely affecting plant health and crop yield. With the growing industrialization process and non-judicious use of chemical fertilizers, the heavy metal mediated chemical toxicity has become one of the major environmental threats for the plants around the globe. The heavy metal ions cause damage to the structural, enzymatic and non-enzymatic components of plant cell, often resulting in loss of cell viability, thus negatively impacting plant growth and development. Plants have also evolved with an extensive and highly efficient mechanism to respond and adapt under such heavy metal toxicity mediated stress conditions. In addition to morpho-anatomical, hormonal and biochemical responses, at the molecular level, plants respond to heavy metal stress induced oxidative and genotoxic damage via the rapid change in the expression of the responsive genes at the transcriptional level. Various families of transcription factors play crucial role in triggering such responses. Apart from transcriptional response, epigenetic modifications have also been found to be essential for maintenance of plant genome stability under genotoxic stress. This review represents a comprehensive survey of recent advances in our understanding of plant responses to heavy metal mediated toxicity in general with particular emphasis on the transcriptional and epigenetic responses and highlights the importance of understanding the potential targets in the associated pathways for improved stress tolerance in crops.
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Affiliation(s)
- Subhajit Dutta
- Department of Botany, UGC Centre of Advanced Studies, The University of Burdwan, Golapbag campus, Burdwan – 713104, West Bengal, India
| | - Mehali Mitra
- Department of Botany, UGC Centre of Advanced Studies, The University of Burdwan, Golapbag campus, Burdwan – 713104, West Bengal, India
| | - Puja Agarwal
- Department of Botany, UGC Centre of Advanced Studies, The University of Burdwan, Golapbag campus, Burdwan – 713104, West Bengal, India
| | - Kalyan Mahapatra
- Department of Botany, UGC Centre of Advanced Studies, The University of Burdwan, Golapbag campus, Burdwan – 713104, West Bengal, India
| | - Sayanti De
- Department of Botany, UGC Centre of Advanced Studies, The University of Burdwan, Golapbag campus, Burdwan – 713104, West Bengal, India
| | - Upasana Sett
- Department of Botany, UGC Centre of Advanced Studies, The University of Burdwan, Golapbag campus, Burdwan – 713104, West Bengal, India
| | - Sujit Roy
- Department of Botany, UGC Centre of Advanced Studies, The University of Burdwan, Golapbag campus, Burdwan – 713104, West Bengal, India
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193
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Dynamic DNA Methylation in Plant Growth and Development. Int J Mol Sci 2018; 19:ijms19072144. [PMID: 30041459 PMCID: PMC6073778 DOI: 10.3390/ijms19072144] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 07/12/2018] [Accepted: 07/20/2018] [Indexed: 12/14/2022] Open
Abstract
DNA methylation is an epigenetic modification required for transposable element (TE) silencing, genome stability, and genomic imprinting. Although DNA methylation has been intensively studied, the dynamic nature of methylation among different species has just begun to be understood. Here we summarize the recent progress in research on the wide variation of DNA methylation in different plants, organs, tissues, and cells; dynamic changes of methylation are also reported during plant growth and development as well as changes in response to environmental stresses. Overall DNA methylation is quite diverse among species, and it occurs in CG, CHG, and CHH (H = A, C, or T) contexts of genes and TEs in angiosperms. Moderately expressed genes are most likely methylated in gene bodies. Methylation levels decrease significantly just upstream of the transcription start site and around transcription termination sites; its levels in the promoter are inversely correlated with the expression of some genes in plants. Methylation can be altered by different environmental stimuli such as pathogens and abiotic stresses. It is likely that methylation existed in the common eukaryotic ancestor before fungi, plants and animals diverged during evolution. In summary, DNA methylation patterns in angiosperms are complex, dynamic, and an integral part of genome diversity after millions of years of evolution.
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194
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Khadka J, Yadav NS, Granot G, Grafi G. Seasonal Growth of Zygophyllum dumosum Boiss.: Summer Dormancy Is Associated with Loss of the Permissive Epigenetic Marker Dimethyl H3K4 and Extensive Reduction in Proteins Involved in Basic Cell Functions. PLANTS 2018; 7:plants7030059. [PMID: 30011962 PMCID: PMC6161207 DOI: 10.3390/plants7030059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 06/22/2018] [Accepted: 07/04/2018] [Indexed: 02/01/2023]
Abstract
Plants thriving in desert environments are suitable for studying mechanisms for plant survival under extreme seasonal climate variation. We studied epigenetic mechanisms underlying seasonal growth cycles in the desert plant Zygophyllum dumosum Boiss., which was previously shown to be deficient in repressive markers of di-methyl and tri-methyl H3K9 and their association with factors regulating basic cell functions. We showed a contingent association between rainfall and seasonal growth and the epigenetic marker of dimethyl H3K4, which disappears upon entry into the dry season and the acquisition of a dormant state. DNA methylation is not affected by a lack of H3K9 di-methyl and tri-methyl. Changes in methylation can occur between the wet and dry season. Proteome analysis of acid soluble fractions revealed an extensive reduction in ribosomal proteins and in proteins involved in chloroplasts and mitochondrial activities during the dry seasons concomitantly with up-regulation of molecular chaperone HSPs. Our results highlight mechanisms underlying Z. dumosum adaptation to seasonal climate variation. Particularly, summer dormancy is associated with a loss of the permissive epigenetic marker dimethyl H3K4, which might facilitate genome compaction concomitantly with a significant reduction in proteins involved in basic cell functions. HSP chaperones might safeguard the integrity of cell components.
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Affiliation(s)
- Janardan Khadka
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
| | - Narendra S Yadav
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
| | - Gila Granot
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 84990, Israel.
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195
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Taudt A, Roquis D, Vidalis A, Wardenaar R, Johannes F, Colomé-Tatché M. METHimpute: imputation-guided construction of complete methylomes from WGBS data. BMC Genomics 2018; 19:444. [PMID: 29879918 PMCID: PMC5992726 DOI: 10.1186/s12864-018-4641-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 04/03/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Whole-genome bisulfite sequencing (WGBS) has become the standard method for interrogating plant methylomes at base resolution. However, deep WGBS measurements remain cost prohibitive for large, complex genomes and for population-level studies. As a result, most published plant methylomes are sequenced far below saturation, with a large proportion of cytosines having either missing data or insufficient coverage. RESULTS Here we present METHimpute, a Hidden Markov Model (HMM) based imputation algorithm for the analysis of WGBS data. Unlike existing methods, METHimpute enables the construction of complete methylomes by inferring the methylation status and level of all cytosines in the genome regardless of coverage. Application of METHimpute to maize, rice and Arabidopsis shows that the algorithm infers cytosine-resolution methylomes with high accuracy from data as low as 6X, compared to data with 60X, thus making it a cost-effective solution for large-scale studies. CONCLUSIONS METHimpute provides methylation status calls and levels for all cytosines in the genome regardless of coverage, thus yielding complete methylomes even with low-coverage WGBS datasets. The method has been extensively tested in plants, but should also be applicable to other species. An implementation is available on Bioconductor.
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Affiliation(s)
- Aaron Taudt
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, Groningen, NL-9713 AV The Netherlands
- Institute of Computational Biology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg, 85764 Germany
| | - David Roquis
- Department of Plant Sciences, Hans Eisenmann-Zentrum for Agricultural Sciences, Technical University Munich, Liesel-Beckmann-Str. 2, Freising, 85354 Germany
| | - Amaryllis Vidalis
- Department of Plant Sciences, Hans Eisenmann-Zentrum for Agricultural Sciences, Technical University Munich, Liesel-Beckmann-Str. 2, Freising, 85354 Germany
| | - René Wardenaar
- Department of Plant Sciences, Hans Eisenmann-Zentrum for Agricultural Sciences, Technical University Munich, Liesel-Beckmann-Str. 2, Freising, 85354 Germany
| | - Frank Johannes
- Department of Plant Sciences, Hans Eisenmann-Zentrum for Agricultural Sciences, Technical University Munich, Liesel-Beckmann-Str. 2, Freising, 85354 Germany
| | - Maria Colomé-Tatché
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, A. Deusinglaan 1, Groningen, NL-9713 AV The Netherlands
- Institute of Computational Biology, Helmholtz Zentrum München, Ingolstädter Landstr. 1, Neuherberg, 85764 Germany
- TUM School of Life Sciences Weihenstephan, Technical University of Munich, Emil-Erlenmeyer-Forum 2, Freising, 85354 Germany
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196
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Li J, Li C, Lu S. Systematic analysis of DEMETER-like DNA glycosylase genes shows lineage-specific Smi-miR7972 involved in SmDML1 regulation in Salvia miltiorrhiza. Sci Rep 2018; 8:7143. [PMID: 29739980 PMCID: PMC5940787 DOI: 10.1038/s41598-018-25315-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 04/09/2018] [Indexed: 11/09/2022] Open
Abstract
DEMETER-like DNA glycosylases (DMLs) initiate the base excision repair-dependent DNA demethylation to regulate a wide range of biological processes in plants. Six putative SmDML genes, termed SmDML1-SmDML6, were identified from the genome of S. miltiorrhiza, an emerging model plant for Traditional Chinese Medicine (TCM) studies. Integrated analysis of gene structures, sequence features, conserved domains and motifs, phylogenetic analysis and differential expression showed the conservation and divergence of SmDMLs. SmDML1, SmDML2 and SmDML4 were significantly down-regulated by the treatment of 5Aza-dC, a general DNA methylation inhibitor, suggesting involvement of SmDMLs in genome DNA methylation change. SmDML1 was predicted and experimentally validated to be target of Smi-miR7972. Computational analysis of forty whole genome sequences and almost all of RNA-seq data from Lamiids revealed that MIR7972s were only distributed in some plants of the three orders, including Lamiales, Solanales and Boraginales, and the number of MIR7972 genes varied among species. It suggests that MIR7972 genes underwent expansion and loss during the evolution of some Lamiids species. Phylogenetic analysis of MIR7972s showed closer evolutionary relationships between MIR7972s in Boraginales and Solanales in comparison with Lamiales. These results provide a valuable resource for elucidating DNA demethylation mechanism in S. miltiorrhiza.
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Affiliation(s)
- Jiang Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No.151 Malianwa North Road, Haidian District, Beijing, 100193, China
| | - Caili Li
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No.151 Malianwa North Road, Haidian District, Beijing, 100193, China
| | - Shanfa Lu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No.151 Malianwa North Road, Haidian District, Beijing, 100193, China.
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197
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Ding M, Chen ZJ. Epigenetic perspectives on the evolution and domestication of polyploid plant and crops. CURRENT OPINION IN PLANT BIOLOGY 2018; 42:37-48. [PMID: 29502038 PMCID: PMC6058195 DOI: 10.1016/j.pbi.2018.02.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/07/2018] [Accepted: 02/13/2018] [Indexed: 05/19/2023]
Abstract
Polyploidy or whole genome duplication (WGD) is a prominent feature for genome evolution of some animals and all flowering plants, including many important crops such as wheat, cotton, and canola. In autopolyploids, genome duplication often perturbs dosage regulation on biological networks. In allopolyploids, interspecific hybridization could induce genetic and epigenetic changes, the effects of which could be amplified by genome doubling (ploidy changes). Albeit the importance of genetic changes, some epigenetic changes can be stabilized and transmitted as epialleles into the progeny, which are subject to natural selection, adaptation, and domestication. Here we review recent advances for general and specific roles of epigenetic changes in the evolution of flowering plants and domestication of agricultural crops.
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Affiliation(s)
- Mingquan Ding
- Departments of Molecular Biosciences and Integrative Biology, Institute for Cellular and Molecular Biology, and Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, TX 78712, USA
| | - Z Jeffrey Chen
- Departments of Molecular Biosciences and Integrative Biology, Institute for Cellular and Molecular Biology, and Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, TX 78712, USA; State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
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198
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Underwood CJ, Choi K, Lambing C, Zhao X, Serra H, Borges F, Simorowski J, Ernst E, Jacob Y, Henderson IR, Martienssen RA. Epigenetic activation of meiotic recombination near Arabidopsis thaliana centromeres via loss of H3K9me2 and non-CG DNA methylation. Genome Res 2018; 28:519-531. [PMID: 29530927 PMCID: PMC5880242 DOI: 10.1101/gr.227116.117] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 01/15/2018] [Indexed: 02/02/2023]
Abstract
Eukaryotic centromeres contain the kinetochore, which connects chromosomes to the spindle allowing segregation. During meiosis, centromeres are suppressed for inter-homolog crossover, as recombination in these regions can cause chromosome missegregation and aneuploidy. Plant centromeres are surrounded by transposon-dense pericentromeric heterochromatin that is epigenetically silenced by histone 3 lysine 9 dimethylation (H3K9me2), and DNA methylation in CG and non-CG sequence contexts. However, the role of these chromatin modifications in control of meiotic recombination in the pericentromeres is not fully understood. Here, we show that disruption of Arabidopsis thaliana H3K9me2 and non-CG DNA methylation pathways, for example, via mutation of the H3K9 methyltransferase genes KYP/SUVH4 SUVH5 SUVH6, or the CHG DNA methyltransferase gene CMT3, increases meiotic recombination in proximity to the centromeres. Using immunocytological detection of MLH1 foci and genotyping by sequencing of recombinant plants, we observe that H3K9me2 and non-CG DNA methylation pathway mutants show increased pericentromeric crossovers. Increased pericentromeric recombination in H3K9me2/non-CG mutants occurs in hybrid and inbred backgrounds and likely involves contributions from both the interfering and noninterfering crossover repair pathways. We also show that meiotic DNA double-strand breaks (DSBs) increase in H3K9me2/non-CG mutants within the pericentromeres, via purification and sequencing of SPO11-1-oligonucleotides. Therefore, H3K9me2 and non-CG DNA methylation exert a repressive effect on both meiotic DSB and crossover formation in plant pericentromeric heterochromatin. Our results may account for selection of enhancer trap Dissociation (Ds) transposons into the CMT3 gene by recombination with proximal transposon launch-pads.
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Affiliation(s)
- Charles J. Underwood
- Howard Hughes Medical Institute, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA;,Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Kyuha Choi
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Christophe Lambing
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Xiaohui Zhao
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Heïdi Serra
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Filipe Borges
- Howard Hughes Medical Institute, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Joe Simorowski
- Howard Hughes Medical Institute, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Evan Ernst
- Howard Hughes Medical Institute, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Yannick Jacob
- Howard Hughes Medical Institute, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Ian R. Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Robert A. Martienssen
- Howard Hughes Medical Institute, Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
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199
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Neeb ZT, Nowacki M. RNA-mediated transgenerational inheritance in ciliates and plants. Chromosoma 2018; 127:19-27. [PMID: 29230532 PMCID: PMC5818585 DOI: 10.1007/s00412-017-0655-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 12/05/2017] [Accepted: 12/05/2017] [Indexed: 11/30/2022]
Abstract
In the age of next-generation sequencing (NGS) and with the availability of whole sequenced genomes and epigenomes, some attention has shifted from purely sequence-based studies to those of heritable epigenetic modifications. Transgenerational inheritance can be defined as heritable changes to the state of DNA that may be passed on to subsequent generations without alterations to the underlying DNA sequence. Although this phenomenon has been extensively studied in many systems, studies of transgenerational inheritance in mammals and other higher-level eukaryotes may be complicated by the fact that many epigenetic marks are reprogrammed during sexual reproduction. This, by definition, may obscure our interpretation of what is in fact truly transgenerational. Therefore, in this mini review, we discuss what is currently known in the field about transgenerational epigenetic inheritance in ciliates and plants, with a particular emphasis on RNA-mediated processes and changes in chromatin states.
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Affiliation(s)
- Zachary T Neeb
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
| | - Mariusz Nowacki
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland.
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200
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Targeted DNA demethylation of the Arabidopsis genome using the human TET1 catalytic domain. Proc Natl Acad Sci U S A 2018; 115:E2125-E2134. [PMID: 29444862 PMCID: PMC5834696 DOI: 10.1073/pnas.1716945115] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
DNA methylation is an epigenetic modification involved in gene silencing. Studies of this modification usually rely on the use of mutants or chemicals that affect methylation maintenance. Those approaches cause global changes in methylation and make difficult the study of the impact of methylation on gene expression or chromatin at specific loci. In this study, we develop tools to target DNA demethylation in plants. We report efficient on-target demethylation and minimal effects on global methylation patterns, and show that in one case, targeted demethylation is heritable. These tools can be used to approach basic questions about DNA methylation biology, as well as to develop new biotechnology strategies to modify gene expression and create new plant trait epialleles. DNA methylation is an important epigenetic modification involved in gene regulation and transposable element silencing. Changes in DNA methylation can be heritable and, thus, can lead to the formation of stable epialleles. A well-characterized example of a stable epiallele in plants is fwa, which consists of the loss of DNA cytosine methylation (5mC) in the promoter of the FLOWERING WAGENINGEN (FWA) gene, causing up-regulation of FWA and a heritable late-flowering phenotype. Here we demonstrate that a fusion between the catalytic domain of the human demethylase TEN-ELEVEN TRANSLOCATION1 (TET1cd) and an artificial zinc finger (ZF) designed to target the FWA promoter can cause highly efficient targeted demethylation, FWA up-regulation, and a heritable late-flowering phenotype. Additional ZF–TET1cd fusions designed to target methylated regions of the CACTA1 transposon also caused targeted demethylation and changes in expression. Finally, we have developed a CRISPR/dCas9-based targeted demethylation system using the TET1cd and a modified SunTag system. Similar to the ZF–TET1cd fusions, the SunTag–TET1cd system is able to target demethylation and activate gene expression when directed to the FWA or CACTA1 loci. Our study provides tools for targeted removal of 5mC at specific loci in the genome with high specificity and minimal off-target effects. These tools provide the opportunity to develop new epialleles for traits of interest, and to reactivate expression of previously silenced genes, transgenes, or transposons.
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