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Liu J, Zhong X. Population epigenetics: DNA methylation in the plant omics era. PLANT PHYSIOLOGY 2024; 194:2039-2048. [PMID: 38366882 PMCID: PMC10980424 DOI: 10.1093/plphys/kiae089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/22/2024] [Accepted: 01/22/2024] [Indexed: 02/18/2024]
Abstract
DNA methylation plays an important role in many biological processes. The mechanisms underlying the establishment and maintenance of DNA methylation are well understood thanks to decades of research using DNA methylation mutants, primarily in Arabidopsis (Arabidopsis thaliana) accession Col-0. Recent genome-wide association studies (GWASs) using the methylomes of natural accessions have uncovered a complex and distinct genetic basis of variation in DNA methylation at the population level. Sequencing following bisulfite treatment has served as an excellent method for quantifying DNA methylation. Unlike studies focusing on specific accessions with reference genomes, population-scale methylome research often requires an additional round of sequencing beyond obtaining genome assemblies or genetic variations from whole-genome sequencing data, which can be cost prohibitive. Here, we provide an overview of recently developed bisulfite-free methods for quantifying methylation and cost-effective approaches for the simultaneous detection of genetic and epigenetic information. We also discuss the plasticity of DNA methylation in a specific Arabidopsis accession, the contribution of DNA methylation to plant adaptation, and the genetic determinants of variation in DNA methylation in natural populations. The recently developed technology and knowledge will greatly benefit future studies in population epigenomes.
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Affiliation(s)
- Jie Liu
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Xuehua Zhong
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
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2
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Liu J, Zhong X. Epiallelic variation of non-coding RNA genes and their phenotypic consequences. Nat Commun 2024; 15:1375. [PMID: 38355746 PMCID: PMC10867003 DOI: 10.1038/s41467-024-45771-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 02/01/2024] [Indexed: 02/16/2024] Open
Abstract
Epigenetic variations contribute greatly to the phenotypic plasticity and diversity. Current functional studies on epialleles have predominantly focused on protein-coding genes, leaving the epialleles of non-coding RNA (ncRNA) genes largely understudied. Here, we uncover abundant DNA methylation variations of ncRNA genes and their significant correlations with plant adaptation among 1001 natural Arabidopsis accessions. Through genome-wide association study (GWAS), we identify large numbers of methylation QTL (methylQTL) that are independent of known DNA methyltransferases and enriched in specific chromatin states. Proximal methylQTL closely located to ncRNA genes have a larger effect on DNA methylation than distal methylQTL. We ectopically tether a DNA methyltransferase MQ1v to miR157a by CRISPR-dCas9 and show de novo establishment of DNA methylation accompanied with decreased miR157a abundance and early flowering. These findings provide important insights into the genetic basis of epigenetic variations and highlight the contribution of epigenetic variations of ncRNA genes to plant phenotypes and diversity.
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Affiliation(s)
- Jie Liu
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Xuehua Zhong
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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3
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Jaegle B, Pisupati R, Soto-Jiménez LM, Burns R, Rabanal FA, Nordborg M. Extensive sequence duplication in Arabidopsis revealed by pseudo-heterozygosity. Genome Biol 2023; 24:44. [PMID: 36895055 PMCID: PMC9999624 DOI: 10.1186/s13059-023-02875-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/13/2023] [Indexed: 03/11/2023] Open
Abstract
BACKGROUND It is apparent that genomes harbor much structural variation that is largely undetected for technical reasons. Such variation can cause artifacts when short-read sequencing data are mapped to a reference genome. Spurious SNPs may result from mapping of reads to unrecognized duplicated regions. Calling SNP using the raw reads of the 1001 Arabidopsis Genomes Project we identified 3.3 million (44%) heterozygous SNPs. Given that Arabidopsis thaliana (A. thaliana) is highly selfing, and that extensively heterozygous individuals have been removed, we hypothesize that these SNPs reflected cryptic copy number variation. RESULTS The heterozygosity we observe consists of particular SNPs being heterozygous across individuals in a manner that strongly suggests it reflects shared segregating duplications rather than random tracts of residual heterozygosity due to occasional outcrossing. Focusing on such pseudo-heterozygosity in annotated genes, we use genome-wide association to map the position of the duplicates. We identify 2500 putatively duplicated genes and validate them using de novo genome assemblies from six lines. Specific examples included an annotated gene and nearby transposon that transpose together. We also demonstrate that cryptic structural variation produces highly inaccurate estimates of DNA methylation polymorphism. CONCLUSIONS Our study confirms that most heterozygous SNP calls in A. thaliana are artifacts and suggest that great caution is needed when analyzing SNP data from short-read sequencing. The finding that 10% of annotated genes exhibit copy-number variation, and the realization that neither gene- nor transposon-annotation necessarily tells us what is actually mobile in the genome suggests that future analyses based on independently assembled genomes will be very informative.
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Affiliation(s)
- Benjamin Jaegle
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria
| | - Rahul Pisupati
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria
| | | | - Robin Burns
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | | | - Magnus Nordborg
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, Vienna, Austria.
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Arce AL, Mencia R, Cambiagno DA, Lang PL, Liu C, Burbano HA, Weigel D, Manavella PA. Polymorphic inverted repeats near coding genes impact chromatin topology and phenotypic traits in Arabidopsis thaliana. Cell Rep 2023; 42:112029. [PMID: 36689329 DOI: 10.1016/j.celrep.2023.112029] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 11/03/2022] [Accepted: 01/10/2023] [Indexed: 01/23/2023] Open
Abstract
Transposons are mobile elements that are commonly silenced to protect eukaryotic genome integrity. In plants, transposable element (TE)-derived inverted repeats (IRs) are commonly found near genes, where they affect host gene expression. However, the molecular mechanisms of such regulation are unclear in most cases. Expression of these IRs is associated with production of 24-nt small RNAs, methylation of the IRs, and drastic changes in local 3D chromatin organization. Notably, many of these IRs differ between Arabidopsis thaliana accessions, causing variation in short-range chromatin interactions and gene expression. CRISPR-Cas9-mediated disruption of two IRs leads to a switch in genome topology and gene expression with phenotypic consequences. Our data show that insertion of an IR near a gene provides an anchor point for chromatin interactions that profoundly impact the activity of neighboring loci. This turns IRs into powerful evolutionary agents that can contribute to rapid adaptation.
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Affiliation(s)
- Agustín L Arce
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina
| | - Regina Mencia
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina
| | - Damian A Cambiagno
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina
| | - Patricia L Lang
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Chang Liu
- Department of Epigenetics, Institute of Biology, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
| | - Hernán A Burbano
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany; Centre for Life's Origins and Evolution, University College London, London, UK
| | - Detlef Weigel
- Department of Molecular Biology, Max Planck Institute for Biology Tübingen, 72076 Tübingen, Germany
| | - Pablo A Manavella
- Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, 3000 Santa Fe, Argentina.
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5
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Nucleotide mismatches prevent intrinsic self-silencing of hpRNA transgenes to enhance RNAi stability in plants. Nat Commun 2022; 13:3926. [PMID: 35798725 PMCID: PMC9263138 DOI: 10.1038/s41467-022-31641-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 06/27/2022] [Indexed: 11/10/2022] Open
Abstract
Hairpin RNA (hpRNA) transgenes are the most successful RNA interference (RNAi) method in plants. Here, we show that hpRNA transgenes are invariably methylated in the inverted-repeat (IR) DNA and the adjacent promoter, causing transcriptional self-silencing. Nucleotide substitutions in the sense sequence, disrupting the IR structure, prevent the intrinsic DNA methylation resulting in more uniform and persistent RNAi. Substituting all cytosine with thymine nucleotides, in a G:U hpRNA design, prevents self-silencing but still allows for the formation of hpRNA due to G:U wobble base-pairing. The G:U design induces effective RNAi in 90–96% of transgenic lines, compared to 57–65% for the traditional hpRNA design. While a traditional hpRNA transgene shows increasing self-silencing from cotyledons to true leaves, its G:U counterpart avoids this and induce RNAi throughout plant growth. Furthermore, siRNAs from G:U and traditional hpRNA show different characteristics and appear to function via different pathways to induce target DNA methylation. Long hairpin RNA (hpRNA) transgenes are the most widely used RNAi technology in plants, but are potentially subject to self-induced transcriptional silencing. Here, the authors show nucleotide mismatches prevent intrinsic self-silencing of hpRNA transgenes in Arabidopsis and tobacco.
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Decoding the sorghum methylome: understanding epigenetic contributions to agronomic traits. Biochem Soc Trans 2022; 50:583-596. [PMID: 35212360 PMCID: PMC9022969 DOI: 10.1042/bst20210908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/01/2022] [Accepted: 02/14/2022] [Indexed: 12/18/2022]
Abstract
DNA methylation is a chromatin modification that plays an essential role in regulating gene expression and genome stability and it is typically associated with gene silencing and heterochromatin. Owing to its heritability, alterations in the patterns of DNA methylation have the potential to provide for epigenetic inheritance of traits. Contemporary epigenomic technologies provide information beyond sequence variation and could supply alternative sources of trait variation for improvement in crops such as sorghum. Yet, compared with other species such as maize and rice, the sorghum DNA methylome is far less well understood. The distribution of CG, CHG, and CHH methylation in the genome is different compared with other species. CG and CHG methylation levels peak around centromeric segments in the sorghum genome and are far more depleted in the gene dense chromosome arms. The genes regulating DNA methylation in sorghum are also yet to be functionally characterised; better understanding of their identity and functional analysis of DNA methylation machinery mutants in diverse genotypes will be important to better characterise the sorghum methylome. Here, we catalogue homologous genes encoding methylation regulatory enzymes in sorghum based on genes in Arabidopsis, maize, and rice. Discovering variation in the methylome may uncover epialleles that provide extra information to explain trait variation and has the potential to be applied in epigenome-wide association studies or genomic prediction. DNA methylation can also improve genome annotations and discover regulatory elements underlying traits. Thus, improving our knowledge of the sorghum methylome can enhance our understanding of the molecular basis of traits and may be useful to improve sorghum performance.
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Ajaykumar H, Ramesh S, Sunitha NC, Anilkumar C. Assessment of natural DNA methylation variation and its association with economically important traits in dolichos bean (Lablab purpureus L. Var. Lignosus) using AMP-PCR assay. J Appl Genet 2021; 62:571-583. [PMID: 34247322 DOI: 10.1007/s13353-021-00648-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 05/30/2021] [Accepted: 06/20/2021] [Indexed: 12/29/2022]
Abstract
As a prelude to exploit DNA methylation-induced variation, we hypothesized the existence of substantial natural DNA methylation variation and its association with economically important traits in dolichos bean, and tested it using amplified methylation polymorphism-polymerase chain reaction (AMP-PCR) assay. DNA methylation patterns such as internal, external, full and non-methylation were amplified in a set of 64 genotypes using 26 customized randomly amplified polymorphic DNA (RAPD) primers containing 5'CCGG3' sequence. The 64 genotypes included 60 germplasm accessions (GA), two advanced breeding lines (ABLs) and two released varieties. The ABLs and released varieties are referred to as improved germplasm accessions (IGA) in this study. The association of DNA methylation patterns with economically important traits such as days to 50% flowering, raceme length, fresh pods plant-1, fresh pod yield plant-1 and 100-fresh seed weight was explored. At least 50 genotypes were polymorphic for DNA methylation patterns at 10 loci generated by seven of the 26 RAPD primers. The GA and IGA differed significantly for total, full and external methylation and the frequency of methylation was higher in GA compared to that in IGA. The genotypes with external methylation produced longer racemes than those with full, internal and non-methylation in that order at polymorphic RAPD-11-242 locus. High pod yielding genotypes had significantly lower frequency of full methylation than low yielding ones. On the contrary, the genotypes that produced heavier fresh seeds harboured higher frequencies of total and externally methylated loci than those that produced lighter fresh seeds.
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Affiliation(s)
- H Ajaykumar
- Department of Genetics and Plant Breeding, College of Agriculture, University of Agricultural Sciences, Bangalore, India
| | - S Ramesh
- Department of Genetics and Plant Breeding, College of Agriculture, University of Agricultural Sciences, Bangalore, India.
| | - N C Sunitha
- Department of Genetics and Plant Breeding, College of Agriculture, University of Agricultural Sciences, Bangalore, India
| | - C Anilkumar
- Department of Genetics and Plant Breeding, College of Agriculture, University of Agricultural Sciences, Bangalore, India.,ICAR-National Rice Research Institute, Cuttack, India
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Noshay JM, Springer NM. Stories that can't be told by SNPs; DNA methylation variation in plant populations. CURRENT OPINION IN PLANT BIOLOGY 2021; 61:101989. [PMID: 33445144 DOI: 10.1016/j.pbi.2020.101989] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/18/2020] [Accepted: 12/11/2020] [Indexed: 05/23/2023]
Abstract
Epigenetic variation has been observed in many plant populations. This variation can influence qualitative and quantitative traits. A key question is whether there is novel information in the epigenome that is not captured by SNP-based genetic markers. The answer likely varies depending on the sources and stability of epigenetic variation as well as the type of population being studied. We consider the epigenetic variation in several plant systems and how this relates to potential for hidden information that could increase our understanding of phenotypic variation.
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Affiliation(s)
- Jaclyn M Noshay
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Nathan M Springer
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA.
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Emanuil N, Akram MS, Ali S, El-Esawi MA, Iqbal M, Alyemeni MN. Peptone-Induced Physio-Biochemical Modulations Reduce Cadmium Toxicity and Accumulation in Spinach ( Spinacia oleracea L.). PLANTS (BASEL, SWITZERLAND) 2020; 9:plants9121806. [PMID: 33352672 PMCID: PMC7765890 DOI: 10.3390/plants9121806] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 05/08/2023]
Abstract
The accumulation of cadmium (Cd) in edible plant parts and fertile lands is a worldwide problem. It negatively influences the growth and productivity of leafy vegetables (e.g., spinach, Spinacia oleracea L.), which have a high tendency to radially accumulate Cd. The present study investigated the influences of peptone application on the growth, biomass, chlorophyll content, gas exchange parameters, antioxidant enzymes activity, and Cd content of spinach plants grown under Cd stress. Cd toxicity negatively affected spinach growth, biomass, chlorophyll content, and gas exchange attributes. However, it increased malondialdehyde (MDA), hydrogen peroxide (H2O2), electrolyte leakage (EL), proline accumulation, ascorbic acid content, Cd content, and activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in spinach plants. The exogenous foliar application of peptone increased the growth, biomass, chlorophyll content, proline accumulation, and gas exchange attributes of spinach plants. Furthermore, the application of peptone decreased Cd uptake and levels of MDA, H2O2, and EL in spinach by increasing the activity of antioxidant enzymes. This enhancement in plant growth and photosynthesis might be due to the lower level of Cd accumulation, which in turn decreased the negative impacts of oxidative stress in plant tissues. Taken together, the findings of the study revealed that peptone is a promising plant growth regulator that represents an efficient approach for the phytoremediation of Cd-polluted soils and enhancement of spinach growth, yield, and tolerance under a Cd-dominant environment.
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Affiliation(s)
- Naila Emanuil
- Department of Botany, Government College University, Faisalabad 38000, Pakistan; (N.E.); (M.I.)
| | - Muhammad Sohail Akram
- Department of Botany, Government College University, Faisalabad 38000, Pakistan; (N.E.); (M.I.)
- Correspondence: (M.S.A.); (S.A.)
| | - Shafaqat Ali
- Department of Environmental Sciences and Engineering, Government College University, Faisalabad 38000, Pakistan
- Department of Biological Sciences and Technology, China Medical University, Taichung 40402, Taiwan
- Correspondence: (M.S.A.); (S.A.)
| | - Mohamed A. El-Esawi
- Botany Department, Faculty of Science, Tanta University, Tanta 31527, Egypt;
| | - Muhammad Iqbal
- Department of Botany, Government College University, Faisalabad 38000, Pakistan; (N.E.); (M.I.)
| | - Mohammed Nasser Alyemeni
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh l1451, Saudi Arabia;
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Hofmeister BT, Denkena J, Colomé-Tatché M, Shahryary Y, Hazarika R, Grimwood J, Mamidi S, Jenkins J, Grabowski PP, Sreedasyam A, Shu S, Barry K, Lail K, Adam C, Lipzen A, Sorek R, Kudrna D, Talag J, Wing R, Hall DW, Jacobsen D, Tuskan GA, Schmutz J, Johannes F, Schmitz RJ. A genome assembly and the somatic genetic and epigenetic mutation rate in a wild long-lived perennial Populus trichocarpa. Genome Biol 2020; 21:259. [PMID: 33023654 PMCID: PMC7539514 DOI: 10.1186/s13059-020-02162-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 09/02/2020] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Plants can transmit somatic mutations and epimutations to offspring, which in turn can affect fitness. Knowledge of the rate at which these variations arise is necessary to understand how plant development contributes to local adaption in an ecoevolutionary context, particularly in long-lived perennials. RESULTS Here, we generate a new high-quality reference genome from the oldest branch of a wild Populus trichocarpa tree with two dominant stems which have been evolving independently for 330 years. By sampling multiple, age-estimated branches of this tree, we use a multi-omics approach to quantify age-related somatic changes at the genetic, epigenetic, and transcriptional level. We show that the per-year somatic mutation and epimutation rates are lower than in annuals and that transcriptional variation is mainly independent of age divergence and cytosine methylation. Furthermore, a detailed analysis of the somatic epimutation spectrum indicates that transgenerationally heritable epimutations originate mainly from DNA methylation maintenance errors during mitotic rather than during meiotic cell divisions. CONCLUSION Taken together, our study provides unprecedented insights into the origin of nucleotide and functional variation in a long-lived perennial plant.
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Affiliation(s)
| | - Johanna Denkena
- Helmholtz Center Munich, German Research Center for Environmental Health, Institute of Computational Biology, Neuherberg, Germany
| | - Maria Colomé-Tatché
- Helmholtz Center Munich, German Research Center for Environmental Health, Institute of Computational Biology, Neuherberg, Germany
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands
- TUM School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Yadollah Shahryary
- Department of Plant Sciences, Technical University of Munich, Liesel-Beckmann-Str. 2, Freising, Germany
| | - Rashmi Hazarika
- Department of Plant Sciences, Technical University of Munich, Liesel-Beckmann-Str. 2, Freising, Germany
- Institute for Advanced Study (IAS), Technical University of Munich, Lichtenbergstr. 2a, Garching, Germany
| | - Jane Grimwood
- HudsonAlpha Institute of Biotechnology, Huntsville, AL, USA
- Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Sujan Mamidi
- HudsonAlpha Institute of Biotechnology, Huntsville, AL, USA
| | - Jerry Jenkins
- HudsonAlpha Institute of Biotechnology, Huntsville, AL, USA
| | | | | | - Shengqiang Shu
- Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Kerrie Barry
- Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Kathleen Lail
- Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Catherine Adam
- Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Anna Lipzen
- Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Dave Kudrna
- Arizona Genomics Institute, School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Jayson Talag
- Arizona Genomics Institute, School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - Rod Wing
- Arizona Genomics Institute, School of Plant Sciences, University of Arizona, Tucson, AZ, USA
| | - David W Hall
- Department of Genetics, University of Georgia, Athens, GA, USA
| | - Daniel Jacobsen
- The Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Gerald A Tuskan
- The Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Jeremy Schmutz
- HudsonAlpha Institute of Biotechnology, Huntsville, AL, USA
- Department of Energy Joint Genome Institute, Walnut Creek, CA, USA
| | - Frank Johannes
- Department of Plant Sciences, Technical University of Munich, Liesel-Beckmann-Str. 2, Freising, Germany.
- Institute for Advanced Study (IAS), Technical University of Munich, Lichtenbergstr. 2a, Garching, Germany.
| | - Robert J Schmitz
- Institute for Advanced Study (IAS), Technical University of Munich, Lichtenbergstr. 2a, Garching, Germany.
- Department of Genetics, University of Georgia, Athens, GA, USA.
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Lauria M, Echegoyen-Nava RA, Rodríguez-Ríos D, Zaina S, Lund G. Inter-individual variation in DNA methylation is largely restricted to tissue-specific differentially methylated regions in maize. BMC PLANT BIOLOGY 2017; 17:52. [PMID: 28231765 PMCID: PMC5324254 DOI: 10.1186/s12870-017-0997-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/08/2017] [Indexed: 05/26/2023]
Abstract
BACKGROUND Variation in DNA methylation across distinct genetic populations, or in response to specific biotic or abiotic stimuli, has typically been studied in leaf DNA from pooled individuals using either reduced representation bisulfite sequencing, whole genome bisulfite sequencing (WGBS) or methylation sensitive amplified polymorphism (MSAP). The latter represents a useful alterative when sample size is large, or when analysing methylation changes in genomes that have yet to be sequenced. In this study we compared variation in methylation across ten individual leaf and endosperm samples from maize hybrid and inbred lines using MSAP. We also addressed the methodological implications of analysing methylation variation using pooled versus individual DNA samples, in addition to the validity of MSAP compared to WGBS. Finally, we analysed a subset of variable and non-variable fragments with respect to genomic location, vicinity to repetitive elements and expression patterns across leaf and endosperm tissues. RESULTS On average, 30% of individuals showed inter-individual methylation variation, mostly of leaf and endosperm-specific differentially methylated DNA regions. With the exception of low frequency demethylation events, the bulk of inter-individual methylation variation (84 and 80% in leaf and endosperm, respectively) was effectively captured in DNA from pooled individuals. Furthermore, available genome-wide methylation data largely confirmed MSAP leaf methylation profiles. Most variable methylation that mapped within genes was associated with CG methylation, and many of such genes showed tissue-specific expression profiles. Finally, we found that the hAT DNA transposon was the most common class II transposable element found in close proximity to variable DNA regions. CONCLUSIONS The relevance of our results with respect to future studies of methylation variation is the following: firstly, the finding that inter-individual methylation variation is largely restricted to tissue-specific differentially methylated DNA regions, underlines the importance of tissue-type when analysing the methylation response to a defined stimulus. Secondly, we show that pooled sample-based MSAP studies are methodologically appropriate to study methylation variation. Thirdly, we confirm that MSAP is a powerful tool when WGBS is not required or feasible, for example in plant species that have yet to be sequenced.
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Affiliation(s)
- Massimiliano Lauria
- Consiglio Nazionale delle Ricerche, Istituto di Biologia e Biotecnologia Agraria, I-20133 Milan, Italy
| | - Rodrigo Antonio Echegoyen-Nava
- Gertrud Lund, Department of Genetic Engineering, CINVESTAV - Unidad Irapuato, Km. 9.6 Libramiento Norte Carretera Irapuato-Leon, Apdo. Postal 629, C. P. 36500 Irapuato, GTO Mexico
| | - Dalia Rodríguez-Ríos
- Gertrud Lund, Department of Genetic Engineering, CINVESTAV - Unidad Irapuato, Km. 9.6 Libramiento Norte Carretera Irapuato-Leon, Apdo. Postal 629, C. P. 36500 Irapuato, GTO Mexico
| | - Silvio Zaina
- Department of Medical Sciences, Division of Health Sciences, León Campus, University of Guanajuato, Guanajuato, Mexico
| | - Gertrud Lund
- Gertrud Lund, Department of Genetic Engineering, CINVESTAV - Unidad Irapuato, Km. 9.6 Libramiento Norte Carretera Irapuato-Leon, Apdo. Postal 629, C. P. 36500 Irapuato, GTO Mexico
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12
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Niederhuth CE, Schmitz RJ. Putting DNA methylation in context: from genomes to gene expression in plants. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:149-156. [PMID: 27590871 DOI: 10.1016/j.bbagrm.2016.08.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 08/20/2016] [Accepted: 08/23/2016] [Indexed: 12/26/2022]
Abstract
Plant DNA methylation is its own language, interpreted by the cell to maintain silencing of transposons, facilitate chromatin structure, and to ensure proper expression of some genes. Just as in any language, context is important. Rather than being a simple "on-off switch", DNA methylation has a range of "meanings" dependent upon the underlying sequence and its location in the genome. Differences in the sequence context of individual sites are established, maintained, and interpreted by differing molecular pathways. Varying patterns of methylation within genes and surrounding sequences are associated with a continuous range of expression differences, from silencing to constitutive expression. These often-subtle differences have been pieced together from years of effort, but have taken off with the advent of methods for assessing methylation across entire genomes. Recognizing these patterns and identifying underlying causes is essential for understanding the function of DNA methylation and its systems-wide contribution to a range of processes in plant genomes. This article is part of a Special Issue entitled: Plant Gene Regulatory Mechanisms and Networks, edited by Dr. Erich Grotewold and Dr. Nathan Springer.
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Affiliation(s)
- Chad E Niederhuth
- Department of Genetics, The University of Georgia, Athens, GA, 30602, USA
| | - Robert J Schmitz
- Department of Genetics, The University of Georgia, Athens, GA, 30602, USA.
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Abstract
Plant genomes encode various small RNAs that function in distinct, yet overlapping, genetic and epigenetic silencing pathways. However, the abundance and diversity of small-RNA classes varies among plant species, suggesting coevolution between environmental adaptations and gene-silencing mechanisms. Biogenesis of small RNAs in plants is well understood, but we are just beginning to uncover their intricate regulation and activity. Here, we discuss the biogenesis of plant small RNAs, such as microRNAs, secondary siRNAs and heterochromatic siRNAs, and their diverse cellular and developmental functions, including in reproductive transitions, genomic imprinting and paramutation. We also discuss the diversification of small-RNA-directed silencing pathways through the expansion of RNA-dependent RNA polymerases, DICER proteins and ARGONAUTE proteins.
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Springer NM, McGinnis KM. Paramutation in evolution, population genetics and breeding. Semin Cell Dev Biol 2015; 44:33-8. [PMID: 26325077 DOI: 10.1016/j.semcdb.2015.08.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 08/18/2015] [Indexed: 11/19/2022]
Abstract
Paramutation is a fascinating phenomenon in which directed allelic interactions result in heritable changes in the state of an allele. Paramutation has been carefully characterized at a handful of loci but the prevalence of paramutable/paramutagenic alleles is not well characterized within genomes or populations. In order to consider the role of paramutation in evolutionary processes and plant breeding, we focused on several questions. First, what causes certain alleles to become subject to paramutation? While paramutation clearly involves epigenetic regulation it is also true that only certain alleles defined by genetic sequences are able to participate in paramutation. Second, what is the prevalence of paramutation? There are only a handful of well-documented examples of paramutation. However, there is growing evidence that many loci may undergo changes in chromatin state or expression that are similar to changes observed as a result of paramutation. Third, how will paramutation events be inherited in natural or artificial populations? Many factors, including stability of epigenetic state, mating style and ploidy, may influence the prevalence of paramutation states within populations. Developing a clear understanding of the mechanisms and frequency of paramutation in crop plant genomes will facilitate new opportunities in genetic manipulation, and will also enhance plant breeding programs and our understanding of genome evolution.
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Affiliation(s)
- Nathan M Springer
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, MN 55108, USA.
| | - Karen M McGinnis
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
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15
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Hagmann J, Becker C, Müller J, Stegle O, Meyer RC, Wang G, Schneeberger K, Fitz J, Altmann T, Bergelson J, Borgwardt K, Weigel D. Century-scale methylome stability in a recently diverged Arabidopsis thaliana lineage. PLoS Genet 2015; 11:e1004920. [PMID: 25569172 PMCID: PMC4287485 DOI: 10.1371/journal.pgen.1004920] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 11/24/2014] [Indexed: 01/17/2023] Open
Abstract
There has been much excitement about the possibility that exposure to specific environments can induce an ecological memory in the form of whole-sale, genome-wide epigenetic changes that are maintained over many generations. In the model plant Arabidopsis thaliana, numerous heritable DNA methylation differences have been identified in greenhouse-grown isogenic lines, but it remains unknown how natural, highly variable environments affect the rate and spectrum of such changes. Here we present detailed methylome analyses in a geographically dispersed A. thaliana population that constitutes a collection of near-isogenic lines, diverged for at least a century from a common ancestor. Methylome variation largely reflected genetic distance, and was in many aspects similar to that of lines raised in uniform conditions. Thus, even when plants are grown in varying and diverse natural sites, genome-wide epigenetic variation accumulates mostly in a clock-like manner, and epigenetic divergence thus parallels the pattern of genome-wide DNA sequence divergence. It continues to be hotly debated to what extent environmentally induced epigenetic change is stably inherited and thereby contributes to short-term adaptation. It has been shown before that natural Arabidopsis thaliana lines differ substantially in their methylation profiles. How much of this is independent of genetic changes remains, however, unclear, especially given that there is very little conservation of methylation between species, simply because the methylated sequences themselves, mostly repeats, are not conserved over millions of years. On the other hand, there is no doubt that artificially induced epialleles can contribute to phenotypic variation. To investigate whether epigenetic differentiation, at least in the short term, proceeds very differently from genetic variation, and whether genome-wide epigenetic fingerprints can be used to uncover local adaptation, we have taken advantage of a near-clonal North American A. thaliana population that has diverged under natural conditions for at least a century. We found that both patterns and rates of methylome variation were in many aspects similar to those of lines grown in stable environments, which suggests that environment-induced changes are only minor contributors to durable genome-wide heritable epigenetic variation.
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Affiliation(s)
- Jörg Hagmann
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Claude Becker
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Jonas Müller
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Oliver Stegle
- Machine Learning and Computational Biology Research Group, Max Planck Institute for Developmental Biology and Max Planck Institute for Intelligent Systems, Tübingen, Germany
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Rhonda C. Meyer
- The Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - George Wang
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Korbinian Schneeberger
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Joffrey Fitz
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Thomas Altmann
- The Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany
| | - Joy Bergelson
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, United States of America
| | - Karsten Borgwardt
- Machine Learning and Computational Biology Research Group, Max Planck Institute for Developmental Biology and Max Planck Institute for Intelligent Systems, Tübingen, Germany
- Center for Bioinformatics (ZBIT), Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Detlef Weigel
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
- * E-mail:
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Ahkami A, Johnson SR, Srividya N, Lange BM. Multiple levels of regulation determine monoterpenoid essential oil compositional variation in the mint family. MOLECULAR PLANT 2015; 8:188-191. [PMID: 25578282 DOI: 10.1016/j.molp.2014.11.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/18/2014] [Indexed: 06/04/2023]
Affiliation(s)
- Amirhossein Ahkami
- Institute of Biological Chemistry and M.J. Murdock Metabolomics Laboratory, Washington State University, Pullman, WA 99164-6340, USA
| | - Sean R Johnson
- Institute of Biological Chemistry and M.J. Murdock Metabolomics Laboratory, Washington State University, Pullman, WA 99164-6340, USA
| | - Narayanan Srividya
- Institute of Biological Chemistry and M.J. Murdock Metabolomics Laboratory, Washington State University, Pullman, WA 99164-6340, USA
| | - Bernd Markus Lange
- Institute of Biological Chemistry and M.J. Murdock Metabolomics Laboratory, Washington State University, Pullman, WA 99164-6340, USA.
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17
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Roles, and establishment, maintenance and erasing of the epigenetic cytosine methylation marks in plants. J Genet 2014; 92:629-66. [PMID: 24371187 DOI: 10.1007/s12041-013-0273-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Heritable information in plants consists of genomic information in DNA sequence and epigenetic information superimposed on DNA sequence. The latter is in the form of cytosine methylation at CG, CHG and CHH elements (where H = A, T orC) and a variety of histone modifications in nucleosomes. The epialleles arising from cytosine methylation marks on the nuclear genomic loci have better heritability than the epiallelic variation due to chromatin marks. Phenotypic variation is increased manifold by epiallele comprised methylomes. Plants (angiosperms) have highly conserved genetic mechanisms to establish, maintain or erase cytosine methylation from epialleles. The methylation marks in plants fluctuate according to the cell/tissue/organ in the vegetative and reproductive phases of plant life cycle. They also change according to environment. Epialleles arise by gain or loss of cytosine methylation marks on genes. The changes occur due to the imperfection of the processes that establish and maintain the marks and on account of spontaneous and stress imposed removal of marks. Cytosine methylation pattern acquired in response to abiotic or biotic stress is often inherited over one to several subsequent generations.Cytosine methylation marks affect physiological functions of plants via their effect(s) on gene expression levels. They also repress transposable elements that are abundantly present in plant genomes. The density of their distribution along chromosome lengths affects meiotic recombination rate, while their removal increases mutation rate. Transposon activation due to loss of methylation causes rearrangements such that new gene regulatory networks arise and genes for microRNAs may originate. Cytosine methylation dynamics contribute to evolutionary changes. This review presents and discusses the available evidence on origin, removal and roles of cytosine methylation and on related processes, such as RNA directed DNA methylation, imprinting, paramutation and transgenerational memory in plants.
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Niederhuth CE, Schmitz RJ. Covering your bases: inheritance of DNA methylation in plant genomes. MOLECULAR PLANT 2014; 7:472-80. [PMID: 24270503 PMCID: PMC3941479 DOI: 10.1093/mp/sst165] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/11/2013] [Indexed: 05/24/2023]
Abstract
Cytosine methylation is an important base modification that is inherited across mitotic and meiotic cell divisions in plant genomes. Heritable methylation variants can contribute to within-species phenotypic variation. Few methylation variants were known until recently, making it possible to begin to address major unanswered questions: the extent of natural methylation variation within plant genomes, its effects on phenotypic variation, its degree of dependence on genotype, and how it fits into an evolutionary context. Techniques like whole-genome bisulfite sequencing (WGBS) make it possible to determine cytosine methylation states at single-base resolution across entire genomes and populations. Application of this method to natural and novel experimental populations is revealing answers to these long-standing questions about the role of DNA methylation in plant genomes.
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Affiliation(s)
| | - Robert J. Schmitz
- To whom correspondence should be addressed. E-mail , fax 706 542 3910, tel. 706-5421882
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19
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Abstract
DNA methylation is a chromatin modification that contributes to epigenetic regulation of gene expression. The inheritance patterns and trans-generational stability of 962 differentially methylated regions (DMRs) were assessed in a panel of 71 near-isogenic lines (NILs) derived from maize (Zea mays) inbred lines B73 and Mo17. The majority of DMRs exhibit inheritance patterns that would be expected for local (cis) inheritance of DNA methylation variation such that DNA methylation level was coupled to local genotype. There are few examples of DNA methylation that exhibit trans-acting control or paramutation-like patterns. The cis-inherited DMRs provide an opportunity to study the stability of inheritance for DNA methylation variation. There was very little evidence for alterations of DNA methylation levels at these DMRs during the generations of the NIL population development. DNA methylation level was associated with local genotypes in nearly all of the >30,000 potential cases of inheritance. The majority of the DMRs were not associated with small RNAs. Together, our results suggest that a significant portion of DNA methylation variation in maize exhibits locally (cis) inherited patterns, is highly stable, and does not require active programming by small RNAs for maintenance. DNA methylation may contribute to heritable epigenetic information in many eukaryotic genomes. In this study, we have documented the inheritance patterns and trans-generational stability for nearly 1000 DNA methylation variants in a segregating maize population. At most loci studied, the DNA methylation differences are locally inherited and are not influenced by the other allele or other genomic regions. The inheritance of DNA methylation levels across generations is quite robust with almost no examples of unstable inheritance, suggesting that DNA methylation differences can be quite stably inherited, even in segregating populations.
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Eichten SR, Briskine R, Song J, Li Q, Swanson-Wagner R, Hermanson PJ, Waters AJ, Starr E, West PT, Tiffin P, Myers CL, Vaughn MW, Springer NM. Epigenetic and genetic influences on DNA methylation variation in maize populations. THE PLANT CELL 2013; 25:2783-97. [PMID: 23922207 PMCID: PMC3784580 DOI: 10.1105/tpc.113.114793] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 07/12/2013] [Accepted: 07/15/2013] [Indexed: 05/18/2023]
Abstract
DNA methylation is a chromatin modification that is frequently associated with epigenetic regulation in plants and mammals. However, genetic changes such as transposon insertions can also lead to changes in DNA methylation. Genome-wide profiles of DNA methylation for 20 maize (Zea mays) inbred lines were used to discover differentially methylated regions (DMRs). The methylation level for each of these DMRs was also assayed in 31 additional maize or teosinte genotypes, resulting in the discovery of 1966 common DMRs and 1754 rare DMRs. Analysis of recombinant inbred lines provides evidence that the majority of DMRs are heritable. A local association scan found that nearly half of the DMRs with common variation are significantly associated with single nucleotide polymorphisms found within or near the DMR. Many of the DMRs that are significantly associated with local genetic variation are found near transposable elements that may contribute to the variation in DNA methylation. Analysis of gene expression in the same samples used for DNA methylation profiling identified over 300 genes with expression patterns that are significantly associated with DNA methylation variation. Collectively, our results suggest that DNA methylation variation is influenced by genetic and epigenetic changes that are often stably inherited and can influence the expression of nearby genes.
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Affiliation(s)
- Steven R. Eichten
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Roman Briskine
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, Minnesota 55455
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas, Austin Texas 78758
| | - Qing Li
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Ruth Swanson-Wagner
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Peter J. Hermanson
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Amanda J. Waters
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Evan Starr
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Patrick T. West
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Peter Tiffin
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
| | - Chad L. Myers
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, Minnesota 55455
| | - Matthew W. Vaughn
- Texas Advanced Computing Center, University of Texas, Austin Texas 78758
| | - Nathan M. Springer
- Microbial and Plant Genomics Institute, Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota 55108
- Address correspondence to
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21
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Becker C, Weigel D. Epigenetic variation: origin and transgenerational inheritance. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:562-7. [PMID: 22939250 DOI: 10.1016/j.pbi.2012.08.004] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 08/16/2012] [Indexed: 05/22/2023]
Abstract
Recent studies have revealed that epigenetic variation in plant populations exceeds genetic diversity and that it is influenced by the environment. Nevertheless, epigenetic differences are not entirely independent of shared ancestry. Epigenetic modifications have gained increasing attention, because one can now study their patterns across the entire genome and in many different individuals. Not only do epigenetic phenomena modulate the activity of the genome in response to environmental stimuli, but they also constitute a potential source of natural variation. Understanding the emergence and heritability of epigenetic variants is critical for understanding how they might become subject to natural selection and thus affect genetic diversity. Here we review progress in characterizing natural epigenetic variants in model and nonmodel plant species and how this work is helping to delineate the role of epigenetic changes in evolution.
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Affiliation(s)
- Claude Becker
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
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22
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Fujimoto R, Sasaki T, Ishikawa R, Osabe K, Kawanabe T, Dennis ES. Molecular mechanisms of epigenetic variation in plants. Int J Mol Sci 2012; 13:9900-9922. [PMID: 22949838 PMCID: PMC3431836 DOI: 10.3390/ijms13089900] [Citation(s) in RCA: 39] [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] [Revised: 07/27/2012] [Accepted: 07/30/2012] [Indexed: 12/11/2022] Open
Abstract
Natural variation is defined as the phenotypic variation caused by spontaneous mutations. In general, mutations are associated with changes of nucleotide sequence, and many mutations in genes that can cause changes in plant development have been identified. Epigenetic change, which does not involve alteration to the nucleotide sequence, can also cause changes in gene activity by changing the structure of chromatin through DNA methylation or histone modifications. Now there is evidence based on induced or spontaneous mutants that epigenetic changes can cause altering plant phenotypes. Epigenetic changes have occurred frequently in plants, and some are heritable or metastable causing variation in epigenetic status within or between species. Therefore, heritable epigenetic variation as well as genetic variation has the potential to drive natural variation.
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Affiliation(s)
- Ryo Fujimoto
- Graduate School of Science and Technology, Niigata University, Nishi-ku, Niigata 950-2181, Japan
| | - Taku Sasaki
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Dr. Bohrgasse 3, Vienna 1030, Austria; E-Mail:
| | - Ryo Ishikawa
- Laboratory of Plant Breeding, Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8510, Japan; E-Mail:
- Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK
| | - Kenji Osabe
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Plant Industry, Canberra ACT 2601, Australia; E-Mails: (K.O.); (E.S.D.)
| | - Takahiro Kawanabe
- Watanabe Seed Co., Ltd, Machiyashiki, Misato-cho, Miyagi 987-8607, Japan; E-Mail:
| | - Elizabeth S. Dennis
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) Plant Industry, Canberra ACT 2601, Australia; E-Mails: (K.O.); (E.S.D.)
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Rangani G, Khodakovskaya M, Alimohammadi M, Hoecker U, Srivastava V. Site-specific methylation in gene coding region underlies transcriptional silencing of the Phytochrome A epiallele in Arabidopsis thaliana. PLANT MOLECULAR BIOLOGY 2012; 79:191-202. [PMID: 22466452 DOI: 10.1007/s11103-012-9906-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 03/17/2012] [Indexed: 05/31/2023]
Abstract
DNA methylation in cytosine residues plays an important role in regulating gene expression. Densely methylated transgenes are often silenced. In contrast, several eukaryotic genomes express moderately methylated genes. These methylations are found in the CG context within the coding region (gene body). The role of gene body methylation in gene expression, however, is not clear. The Arabidopsis Phytochrome A epiallele, phyA', carries hypermethylation in several CG sites resident to the coding region. As a result, phyA' is transcriptionally silenced and confers strong mutant phenotype. Mutations in chromatin modification factors and RNAi genes failed to revert the mutant phenotype, suggesting the involvement of a distinct epigenetic mechanism associated with phyA' silencing. Using the forward genetics approach, a suppressor line, termed as suppressor of p hyA' silencing 1 (sps1), was isolated. Genetic and molecular analysis revealed that sps1 mutation reactivates the phyA' locus without altering its methylation density. However, hypomethylation at a specific CG site in exon 1 was consistently associated with the release of phyA' silencing. While gene underlying sps1 mutation is yet to be identified, microarray analysis suggested that its targets are the expressed genes or euchromatic loci in Arabidopsis genome. By identifying the association of phyA' silencing with the methylation of a specific CG site in exon 1, the present work shows that site-specific methylation confers greater effect on transcription than the methylation density within gene-body. Further, as the identified site (exon 1) is not critical for the promoter activity, transcription elongation rather than transcription initiation is likely to be affected by this site-specific CG methylation.
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Affiliation(s)
- Gulab Rangani
- Department of Crop, Soil and Environmental Sciences, Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA.
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Schmitz RJ, Ecker JR. Epigenetic and epigenomic variation in Arabidopsis thaliana. TRENDS IN PLANT SCIENCE 2012; 17:149-54. [PMID: 22342533 PMCID: PMC3645451 DOI: 10.1016/j.tplants.2012.01.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 12/23/2011] [Accepted: 01/04/2012] [Indexed: 05/04/2023]
Abstract
Arabidopsis thaliana (Arabidopsis) is ideally suited for studies of natural phenotypic variation. This species has also provided an unparalleled experimental system to explore the mechanistic link between genetic and epigenetic variation, especially with regard to cytosine methylation. Using high-throughput sequencing methods, genotype to epigenotype to phenotype observations can now be extended to plant populations. We review the evidence for induced and spontaneous epigenetic variants that have been identified in Arabidopsis in the laboratory and discuss how these experimental observations could explain existing variation in the wild.
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Affiliation(s)
- Robert J Schmitz
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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25
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Maeda H, Dudareva N. The shikimate pathway and aromatic amino Acid biosynthesis in plants. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:73-105. [PMID: 22554242 DOI: 10.1146/annurev-arplant-042811-105439] [Citation(s) in RCA: 722] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
L-tryptophan, L-phenylalanine, and L-tyrosine are aromatic amino acids (AAAs) that are used for the synthesis of proteins and that in plants also serve as precursors of numerous natural products, such as pigments, alkaloids, hormones, and cell wall components. All three AAAs are derived from the shikimate pathway, to which ≥30% of photosynthetically fixed carbon is directed in vascular plants. Because their biosynthetic pathways have been lost in animal lineages, the AAAs are essential components of the diets of humans, and the enzymes required for their synthesis have been targeted for the development of herbicides. This review highlights recent molecular identification of enzymes of the pathway and summarizes the pathway organization and the transcriptional/posttranscriptional regulation of the AAA biosynthetic network. It also identifies the current limited knowledge of the subcellular compartmentalization and the metabolite transport involved in the plant AAA pathways and discusses metabolic engineering efforts aimed at improving production of the AAA-derived plant natural products.
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Affiliation(s)
- Hiroshi Maeda
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907-2010, USA.
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26
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Enke RA, Dong Z, Bender J. Small RNAs prevent transcription-coupled loss of histone H3 lysine 9 methylation in Arabidopsis thaliana. PLoS Genet 2011; 7:e1002350. [PMID: 22046144 PMCID: PMC3203196 DOI: 10.1371/journal.pgen.1002350] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 08/30/2011] [Indexed: 11/24/2022] Open
Abstract
In eukaryotes, histone H3 lysine 9 methylation (H3K9me) mediates silencing of invasive sequences to prevent deleterious consequences including the expression of aberrant gene products and mobilization of transposons. In Arabidopsis thaliana, H3K9me maintained by SUVH histone methyltransferases (MTases) is associated with cytosine methylation (5meC) maintained by the CMT3 cytosine MTase. The SUVHs contain a 5meC binding domain and CMT3 contains an H3K9me binding domain, suggesting that the SUVH/CMT3 pathway involves an amplification loop between H3K9me and 5meC. However, at loci subject to read-through transcription, the stability of the H3K9me/5meC loop requires a mechanism to counteract transcription-coupled loss of H3K9me. Here we use the duplicated PAI genes, which stably maintain SUVH-dependent H3K9me and CMT3-dependent 5meC despite read-through transcription, to show that when PAI sRNAs are depleted by dicer ribonuclease mutations, PAI H3K9me and 5meC levels are reduced and remaining PAI 5meC is destabilized upon inbreeding. The dicer mutations confer weaker reductions in PAI 5meC levels but similar or stronger reductions in PAI H3K9me levels compared to a cmt3 mutation. This comparison indicates a connection between sRNAs and maintenance of H3K9me independent of CMT3 function. The dicer mutations reduce PAI H3K9me and 5meC levels through a distinct mechanism from the known role of dicer-dependent sRNAs in guiding the DRM2 cytosine MTase because the PAI genes maintain H3K9me and 5meC at levels similar to wild type in a drm2 mutant. Our results support a new role for sRNAs in plants to prevent transcription-coupled loss of H3K9me. Methylation of histone H3 at the lysine 9 position (H3K9me) is a fundamental chromatin modification that suppresses expression from invasive and repetitive sequences such as transposons. In plant genomes, regions modified by H3K9me are maintained with precise boundaries. However, at junctions where H3K9me target regions are subject to read-through transcription from outside promoters, the stability of H3K9me patterns is jeopardized by transcription-coupled processes that remove this modification. We show that maintenance of H3K9me patterns at such vulnerable sites requires small RNAs corresponding to the H3K9me target region. We use a sensitive reporter system to show that, in the absence of small RNAs, target regions subject to read-through transcription undergo an immediate reduction in H3K9me levels, followed by further losses in progeny plants upon inbreeding. Our results support a new function for small RNAs in maintaining accurate H3K9me patterns in the plant genome.
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Affiliation(s)
- Raymond A. Enke
- Wilmer Eye Institute, Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Zhicheng Dong
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island, United States of America
| | - Judith Bender
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island, United States of America
- * E-mail:
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27
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Hauser MT, Aufsatz W, Jonak C, Luschnig C. Transgenerational epigenetic inheritance in plants. BIOCHIMICA ET BIOPHYSICA ACTA 2011. [PMID: 21515434 DOI: 10.1016/j.bbagrm.2011.03.007.transgenerational] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Interest in transgenerational epigenetic inheritance has intensified with the boosting of knowledge on epigenetic mechanisms regulating gene expression during development and in response to internal and external signals such as biotic and abiotic stresses. Starting with an historical background of scantily documented anecdotes and their consequences, we recapitulate the information gathered during the last 60 years on naturally occurring and induced epialleles and paramutations in plants. We present the major players of epigenetic regulation and their importance in controlling stress responses. The effect of diverse stressors on the epigenetic status and its transgenerational inheritance is summarized from a mechanistic viewpoint. The consequences of transgenerational epigenetic inheritance are presented, focusing on the knowledge about its stability, and in relation to genetically fixed mutations, recombination, and genomic rearrangement. We conclude with an outlook on the importance of transgenerational inheritance for adaptation to changing environments and for practical applications. This article is part of a Special Issue entitled "Epigenetic control of cellular and developmental processes in plants".
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Affiliation(s)
- Marie-Theres Hauser
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences Vienna, Muthgasse 18, Austria
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Hauser MT, Aufsatz W, Jonak C, Luschnig C. Transgenerational epigenetic inheritance in plants. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:459-68. [PMID: 21515434 DOI: 10.1016/j.bbagrm.2011.03.007] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 03/25/2011] [Accepted: 03/31/2011] [Indexed: 01/08/2023]
Abstract
Interest in transgenerational epigenetic inheritance has intensified with the boosting of knowledge on epigenetic mechanisms regulating gene expression during development and in response to internal and external signals such as biotic and abiotic stresses. Starting with an historical background of scantily documented anecdotes and their consequences, we recapitulate the information gathered during the last 60 years on naturally occurring and induced epialleles and paramutations in plants. We present the major players of epigenetic regulation and their importance in controlling stress responses. The effect of diverse stressors on the epigenetic status and its transgenerational inheritance is summarized from a mechanistic viewpoint. The consequences of transgenerational epigenetic inheritance are presented, focusing on the knowledge about its stability, and in relation to genetically fixed mutations, recombination, and genomic rearrangement. We conclude with an outlook on the importance of transgenerational inheritance for adaptation to changing environments and for practical applications. This article is part of a Special Issue entitled "Epigenetic control of cellular and developmental processes in plants".
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Affiliation(s)
- Marie-Theres Hauser
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences Vienna, Muthgasse 18, Austria
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29
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Tzin V, Galili G. New insights into the shikimate and aromatic amino acids biosynthesis pathways in plants. MOLECULAR PLANT 2010; 3:956-72. [PMID: 20817774 DOI: 10.1093/mp/ssq048] [Citation(s) in RCA: 356] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The aromatic amino acids phenylalanine, tyrosine, and tryptophan in plants are not only essential components of protein synthesis, but also serve as precursors for a wide range of secondary metabolites that are important for plant growth as well as for human nutrition and health. The aromatic amino acids are synthesized via the shikimate pathway followed by the branched aromatic amino acids biosynthesis pathway, with chorismate serving as a major intermediate branch point metabolite. Yet, the regulation and coordination of synthesis of these amino acids are still far from being understood. Recent studies on these pathways identified a number of alternative cross-regulated biosynthesis routes with unique evolutionary origins. Although the major route of Phe and Tyr biosynthesis in plants occurs via the intermediate metabolite arogenate, recent studies suggest that plants can also synthesize phenylalanine via the intermediate metabolite phenylpyruvate (PPY), similarly to many microorganisms. Recent studies also identified a number of transcription factors regulating the expression of genes encoding enzymes of the shikimate and aromatic amino acids pathways as well as of multiple secondary metabolites derived from them in Arabidopsis and in other plant species.
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Affiliation(s)
- Vered Tzin
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
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30
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Rodríguez López CM, Guzmán Asenjo B, Lloyd AJ, Wilkinson MJ. Direct detection and quantification of methylation in nucleic acid sequences using high-resolution melting analysis. Anal Chem 2010; 82:9100-8. [PMID: 20945868 DOI: 10.1021/ac1024057] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
High-resolution melting (HRM) analysis exploits the reduced thermal stability of DNA fragments that contain base mismatches to detect single nucleotide polymorphisms (SNPs). However, the capacity of HRM to reveal other features of DNA chemistry remains unexplored. DNA methylation plays a key role in regulating gene expression and is essential for normal development in many higher organisms. The presence of methylated bases perturbs the double-stranded DNA structure, although its effect on DNA thermal stability is largely unknown. Here, we reveal that methylated DNA has enhanced thermal stability and is sufficiently divergent from nonmethylated DNA to allow detection and quantification by HRM analysis. This approach reliably distinguishes between sequence-identical DNA differing only in the methylation of one base. The method also provides accurate discrimination between mixes of methylated and nonmethylated DNAs, allowing discrimination between DNA that is 1% and 0% methylated and also between 97.5% and 100% methylated. Thus, the method provides a new means of adjusting thermal optima for DNA hybridization and PCR-based techniques and to empirically measure the impact of DNA methylation marks on the thermostability of regulatory regions. In the longer term, it could enable the development of new techniques to quantify methylated DNA.
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Affiliation(s)
- Carlos M Rodríguez López
- Aberystwyth University, IBERS-Institute of Biological, Environmental and Rural Sciences, Aberystwyth, Wales, SY23 3DA, UK
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31
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Molnar A, Melnyk CW, Bassett A, Hardcastle TJ, Dunn R, Baulcombe DC. Small silencing RNAs in plants are mobile and direct epigenetic modification in recipient cells. Science 2010; 328:872-5. [PMID: 20413459 DOI: 10.1126/science.1187959] [Citation(s) in RCA: 473] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A silencing signal in plants with an RNA specificity determinant moves through plasmodesmata and the phloem. To identify the mobile RNA, we grafted Arabidopsis thaliana shoots to roots that would be a recipient for the silencing signal. Using mutants that block small RNA (sRNA) biogenesis in either source or recipient tissue, we found that transgene-derived sRNA as well as a substantial proportion of the endogenous sRNA had moved across the graft union, and we provide evidence that 24-nucleotide mobile sRNAs direct epigenetic modifications in the genome of the recipient cells. Mobile sRNA thus represents a mechanism for transmitting the specification of epigenetic modification and could affect genome defense and responses to external stimuli that have persistent effects in plants.
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Affiliation(s)
- Attila Molnar
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
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32
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Tzin V, Galili G. The Biosynthetic Pathways for Shikimate and Aromatic Amino Acids in Arabidopsis thaliana. THE ARABIDOPSIS BOOK 2010; 8:e0132. [PMID: 22303258 PMCID: PMC3244902 DOI: 10.1199/tab.0132] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The aromatic amino acids phenylalanine, tyrosine and tryptophan in plants are not only essential components of protein synthesis, but also serve as precursors for a wide range of secondary metabolites that are important for plant growth as well as for human nutrition and health. The aromatic amino acids are synthesized via the shikimate pathway followed by the branched aromatic amino acid metabolic pathway, with chorismate serving as a major branch point intermediate metabolite. Yet, the regulation of their synthesis is still far from being understood. So far, only three enzymes in this pathway, namely, chorismate mutase of phenylalanine and tyrosine synthesis, tryptophan synthase of tryptophan biosynthesis and arogenate dehydratase of phenylalanine biosynthesis, proved experimentally to be allosterically regulated. The major biosynthesis route of phenylalanine in plants occurs via arogenate. Yet, recent studies suggest that an alternative route of phynylalanine biosynthesis via phenylpyruvate may also exist in plants, similarly to many microorganisms. Several transcription factors regulating the expression of genes encoding enzymes of both the shikimate pathway and aromatic amino acid metabolism have also been recently identified in Arabidopsis and other plant species.
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Affiliation(s)
- Vered Tzin
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100 Israel
| | - Gad Galili
- Department of Plant Sciences, The Weizmann Institute of Science, Rehovot 76100 Israel
- Address correspondence to
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33
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Krizova K, Fojtova M, Depicker A, Kovarik A. Cell culture-induced gradual and frequent epigenetic reprogramming of invertedly repeated tobacco transgene epialleles. PLANT PHYSIOLOGY 2009; 149:1493-504. [PMID: 19129419 PMCID: PMC2649402 DOI: 10.1104/pp.108.133165] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 12/22/2008] [Indexed: 05/04/2023]
Abstract
Using a two-component transgene system involving two epiallelic variants of the invertedly repeated transgenes in locus 1 (Lo1) and a homologous single-copy transgene locus 2 (Lo2), we have studied the stability of the methylation patterns and trans-silencing interactions in cell culture and regenerated tobacco (Nicotiana tabacum) plants. The posttranscriptionally silenced (PTGS) epiallele of the Lo1 trans-silences and trans-methylates the target Lo2 in a hybrid (Lo1/Lo2 line), while its transcriptionally silenced variant (Lo1E) does not. This pattern was stable over several generations in plants. However, in early Lo1E/Lo2 callus, decreased transgene expression and partial loss of Lo1E promoter methylation compared with leaf tissue in the parental plant were observed. Analysis of small RNA species and coding region methylation suggested that the transgenes were silenced by a PTGS mechanism. The Lo1/Lo2 line remained silenced, but the nonmethylated Lo1 promoter acquired partial methylation in later callus stages. These data indicate that a cell culture process has brought both epialleles to a similar epigenetic ground. Bisulfite sequencing of the 35S promoter within the Lo1 silencer revealed molecules with no, intermediate, and high levels of methylation, demonstrating, to our knowledge for the first time, cell-to-cell methylation diversity of callus. Regenerated plants showed high interindividual but low intraindividual epigenetic variability, indicating that the callus-induced epiallelic variants were transmitted to plants and became fixed. We propose that epigenetic changes associated with dedifferentiation might influence regulatory pathways mediated by trans-PTGS processes.
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Affiliation(s)
- Katerina Krizova
- Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 65 Brno, Czech Republic
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34
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Berchowitz LE, Copenhaver GP. Visual markers for detecting gene conversion directly in the gametes of Arabidopsis thaliana. Methods Mol Biol 2009; 557:99-114. [PMID: 19799179 DOI: 10.1007/978-1-59745-527-5_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Measuring meiotic gene conversion is important both because of its role in the fundamental mechanisms of meiotic recombination and because of its influence on linkage relationships and allelic diversity in the genome. Historically, gene conversion has been most thoroughly examined in fungal organisms through the use of tetrad analysis. Here we describe a method for using tetrad analysis in the model plant Arabidopsis thaliana to detect and quantify gene conversion events - a resource unavailable in most other higher eukaryotic model systems.
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Affiliation(s)
- Luke E Berchowitz
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
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35
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Yazaki J, Gregory BD, Ecker JR. Mapping the genome landscape using tiling array technology. CURRENT OPINION IN PLANT BIOLOGY 2007; 10:534-42. [PMID: 17703988 PMCID: PMC2665186 DOI: 10.1016/j.pbi.2007.07.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 06/29/2007] [Accepted: 07/09/2007] [Indexed: 05/16/2023]
Abstract
With the availability of complete genome sequences for a growing number of organisms, high-throughput methods for gene annotation and analysis of genome dynamics are needed. The application of whole-genome tiling microarrays for studies of global gene expression is providing a more unbiased view of the transcriptional activity within genomes. For example, this approach has led to the identification and isolation of many novel non-protein-coding RNAs (ncRNAs), which have been suggested to comprise a major component of the transcriptome that have novel functions involved in epigenetic regulation of the genome. Additionally, tiling arrays have been recently applied to the study of histone modifications and methylation of cytosine bases (DNA methylation). Surprisingly, recent studies combining the analysis of gene expression (transcriptome) and DNA methylation (methylome) using whole-genome tiling arrays revealed that DNA methylation regulates the expression levels of many ncRNAs. Further capture and integration of additional types of genome-wide data sets will help to illuminate additional hidden features of the dynamic genomic landscape that are regulated by both genetic and epigenetic pathways in plants.
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Affiliation(s)
- Junshi Yazaki
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Brian D. Gregory
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Joseph R. Ecker
- Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
- Corresponding author: Joseph R. Ecker ()
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36
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Mull L, Ebbs ML, Bender J. A histone methylation-dependent DNA methylation pathway is uniquely impaired by deficiency in Arabidopsis S-adenosylhomocysteine hydrolase. Genetics 2006; 174:1161-71. [PMID: 16951055 PMCID: PMC1667058 DOI: 10.1534/genetics.106.063974] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
S-adenosylhomocysteine hydrolase (SAH) is a key enzyme in the maintenance of methylation homeostasis in eukaryotes because it is needed to metabolize the by-product of transmethylation reactions, S-adenosylhomocysteine (AdoHcy), which causes by-product inhibition of methyltransferases (MTase's). Complete loss of SAH function is lethal. Partial loss of SAH function causes pleiotropic effects including developmental abnormalities and reduced cytosine methylation. Here we describe a novel partial-function missense allele of the Arabidopsis SAH1 gene that causes loss of cytosine methylation specifically in non-CG contexts controlled by the CMT3 DNA MTase and transcriptional reactivation of a silenced reporter gene, without conferring developmental abnormalities. The CMT3 pathway depends on histone H3 lysine 9 methylation (H3 mK9) to guide DNA methylation. Our results suggest that this pathway is uniquely sensitive to SAH impairment because of its requirement for two transmethylation reactions that can both be inhibited by AdoHcy. Our results further suggest that gene silencing pathways involving an interplay between histone and DNA methylation in other eukaryotes can be selectively impaired by controlled SAH downregulation.
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Affiliation(s)
- Lori Mull
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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37
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Dong ZY, Wang YM, Zhang ZJ, Shen Y, Lin XY, Ou XF, Han FP, Liu B. Extent and pattern of DNA methylation alteration in rice lines derived from introgressive hybridization of rice and Zizania latifolia Griseb. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2006; 113:196-205. [PMID: 16791687 DOI: 10.1007/s00122-006-0286-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Accepted: 03/31/2006] [Indexed: 05/04/2023]
Abstract
We have reported previously that introgression by Zizania latifolia resulted in extensive DNA methylation changes in the recipient rice genome, as detected by a set of pre-selected DNA segments. In this study, using the methylation-sensitive amplified polymorphism (MSAP) method, we globally assessed the extent and pattern of cytosine methylation alterations in three typical introgression lines relative to their rice parent at approximately 2,700 unbiased genomic loci each representing a recognition site cleaved by one or both of the isoschizomers, HpaII/MspI. Based on differential digestion by the isoschizomers, it is estimated that 15.9% of CCGG sites are either fully methylated at the internal Cs and/or hemi-methylated at the external Cs in the rice parental cultivar Matsumae. In comparison, a statistically significant increase in the overall level of both methylation types was detected in all three studied introgression lines (19.2, 18.6, 19.6%, respectively). Based on comparisons of MSAP profiles between the isoschizomers within the rice parent and between parent and the introgression lines, four major groups of MSAP banding patterns are recognized, which can be further divided into various subgroups as a result of inheritance of, or variation in, parental methylation patterns. The altered methylation patterns include hyper- and hypomethylation changes, as well as inter-conversion of hemi- to full-methylation, or vice versa, at the relevant CCGG site(s). Most alterations revealed by MSAP in low-copy loci can be validated by DNA gel blot analysis. The changed methylation patterns are uniform among randomly selected individuals for a given introgression line within or among selfed generations. Sequencing on 31 isolated fragments that showed different changing patterns in the introgression line(s) allowed their mapping onto variable regions on one or more of the 12 rice chromosomes. These segments include protein-coding genes, transposon/retrotransposons and sequences with no homology. Possible causes for the introgression-induced methylation changes and their implications for genome evolution and crop breeding are discussed.
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Affiliation(s)
- Z Y Dong
- Laboratory of Plant Molecular Epigenetics, Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China
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38
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Klenov MS, Gvozdev VA. Heterochromatin formation: role of short RNAs and DNA methylation. BIOCHEMISTRY (MOSCOW) 2006; 70:1187-98. [PMID: 16336177 DOI: 10.1007/s10541-005-0247-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The role of small double-stranded RNAs is considered in formation of silent chromatin structure. Small RNAs are implicated in the regulation of individual gene transcription, suppression of transposon expression, and in maintaining functional structure of extended heterochromatic regions. Interrelations between short RNA-dependent gene silencing, histone modifications, and DNA methylation are discussed. Specific features of RNA-induced chromatin repression in various eucaryotes are also described.
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Affiliation(s)
- M S Klenov
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, 123182, Russia.
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39
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Ebbs ML, Bender J. Locus-specific control of DNA methylation by the Arabidopsis SUVH5 histone methyltransferase. THE PLANT CELL 2006; 18:1166-76. [PMID: 16582009 PMCID: PMC1456864 DOI: 10.1105/tpc.106.041400] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In Arabidopsis thaliana, heterochromatin formation is guided by double-stranded RNA (dsRNA), which triggers methylation of histone H3 at Lys-9 (H3 mK9) and CG plus non-CG methylation on identical DNA sequences. At heterochromatin targets including transposons and centromere repeats, H3 mK9 mediated by the Su(var)3-9 homologue 4 (SUVH4)/KYP histone methyltransferase (MTase) is required for the maintenance of non-CG methylation by the CMT3 DNA MTase. Here, we show that although SUVH4 is the major H3 K9 MTase, the SUVH5 protein also has histone MTase activity in vitro and contributes to the maintenance of H3 mK9 and CMT3-mediated non-CG methylation in vivo. Strikingly, the relative contributions of SUVH4, SUVH5, and a third related histone MTase, SUVH6, to non-CG methylation are locus-specific. For example, SUVH4 and SUVH5 together control transposon sequences with only a minor contribution from SUVH6, whereas SUVH4 and SUVH6 together control a transcribed inverted repeat source of dsRNA with only a minor contribution from SUVH5. This locus-specific variation suggests different mechanisms for recruiting or activating SUVH enzymes at different heterochromatic sequences. The suvh4 suvh5 suvh6 triple mutant loses both monomethyl and dimethyl H3 K9 at target loci. The suvh4 suvh5 suvh6 mutant also displays a loss of non-CG methylation similar to a cmt3 mutant, indicating that SUVH4, SUVH5, and SUVH6 together control CMT3 activity.
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Affiliation(s)
- Michelle L Ebbs
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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40
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Ebbs ML, Bartee L, Bender J. H3 lysine 9 methylation is maintained on a transcribed inverted repeat by combined action of SUVH6 and SUVH4 methyltransferases. Mol Cell Biol 2005; 25:10507-15. [PMID: 16287862 PMCID: PMC1291251 DOI: 10.1128/mcb.25.23.10507-10515.2005] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcribed inverted repeats are potent triggers for RNA interference and RNA-directed DNA methylation in plants through the production of double-stranded RNA (dsRNA). For example, a transcribed inverted repeat of endogenous genes in Arabidopsis thaliana, PAI1-PAI4, guides methylation of itself as well as two unlinked duplicated PAI genes, PAI2 and PAI3. In previous work, we found that mutations in the SUVH4/KYP histone H3 lysine 9 (H3 K9) methyltransferase cause a loss of DNA methylation on PAI2 and PAI3, but not on the inverted repeat. Here we use chromatin immunoprecipitation analysis to show that the transcribed inverted repeat carries H3 K9 methylation, which is maintained even in an suvh4 mutant. PAI1-PAI4 H3 K9 methylation and DNA methylation are also maintained in an suvh6 mutant, which is defective for a gene closely related to SUVH4. However, both epigenetic modifications are reduced at this locus in an suvh4 suvh6 double mutant. In contrast, SUVH6 does not play a significant role in maintenance of H3 K9 or DNA methylation on PAI2, transposon sequences, or centromere repeat sequences. Thus, SUVH6 is preferentially active at a dsRNA source locus versus targets for RNA-directed chromatin modifications.
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Affiliation(s)
- Michelle L Ebbs
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA
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41
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Bender J. DNA methylation of the endogenous PAI genes in Arabidopsis. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2005; 69:145-53. [PMID: 16117644 DOI: 10.1101/sqb.2004.69.145] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- J Bender
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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42
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Ruiz-García L, Cervera MT, Martínez-Zapater JM. DNA methylation increases throughout Arabidopsis development. PLANTA 2005; 222:301-6. [PMID: 15968513 DOI: 10.1007/s00425-005-1524-6] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Accepted: 02/16/2005] [Indexed: 05/03/2023]
Abstract
We used amplified fragment length polymorphisms (AFLP) to analyze the stability of DNA methylation throughout Arabidopsis development. AFLP can detect genome-wide changes in cytosine methylation produced by DNA demethylation agents, such as 5-azacytidine, or specific mutations at the DDM1 locus. In both cases, cytosine demethylation is associated with a general increase in the presence of amplified fragments. Using this approach, we followed DNA methylation at methylation sensitive restriction sites throughout Arabidopsis development. The results show a progressive DNA methylation trend from cotyledons to vegetative organs to reproductive organs.
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Affiliation(s)
- L Ruiz-García
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, CSIC, Campus de la Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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43
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Abstract
Double-stranded RNAs (dsRNAs) and their 'diced' small RNA products can guide key developmental and defense mechanisms in eukaryotes. Some RNA-directed mechanisms act at a post-transcriptional level to degrade target messenger RNAs. However, dsRNA-derived species can also direct changes in the chromatin structure of DNA regions with which they share sequence identity. For example, plants use such RNA species to lay down cytosine methylation imprints on identical DNA sequences, providing a fundamental mark for the formation of transcriptionally silent heterochromatin. Thus, RNA can feed backwards to modulate the accessibility of information stored in the DNA of cognate genes. RNA triggers for DNA methylation can come from different sources, including invasive viral, transgene or transposon sequences, and in some cases are derived from single-stranded RNA precursors by RNA-dependent RNA polymerases. The mechanism by which RNA signals are translated into DNA methylation imprints is currently unknown, but two plant-specific types of cytosine methyltransferase have been implicated in this process. RNA can also direct heterochromatin formation in fission yeast and Drosophila, but in these organisms the process occurs in the absence of DNA methylation.
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Affiliation(s)
- Olivier Mathieu
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA
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44
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Melquist S, Bender J. An internal rearrangement in an Arabidopsis inverted repeat locus impairs DNA methylation triggered by the locus. Genetics 2004; 166:437-48. [PMID: 15020434 PMCID: PMC1470711 DOI: 10.1534/genetics.166.1.437] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In plants, transcribed inverted repeats trigger RNA interference (RNAi) and DNA methylation of identical sequences. RNAi is caused by processing of the double-stranded RNA (dsRNA) transcript into small RNAs that promote degradation of complementary RNA sequences. However, the signals for DNA methylation remain to be fully elucidated. The Arabidopsis tryptophan biosynthetic PAI genes provide an endogenous inverted repeat that triggers DNA methylation of PAI-identical sequences. In the Wassilewskija strain, two PAI genes are arranged as a tail-to-tail inverted repeat and transcribed from an unmethylated upstream promoter. This locus directs its own methylation, as well as methylation of two unlinked singlet PAI genes. Previously, we showed that the locus is likely to make an RNA signal for methylation because suppressed transcription of the inverted repeat leads to reduced PAI methylation. Here we characterize a central rearrangement in the inverted repeat that also confers reduced PAI methylation. The rearrangement creates a premature polyadenylation signal and suppresses readthrough transcription into palindromic PAI sequences. Thus, a likely explanation for the methylation defect of the mutant locus is a failure to produce readthrough dsRNA methylation triggers.
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Affiliation(s)
- Stacey Melquist
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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45
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Liu Z, Wang Y, Shen Y, Guo W, Hao S, Liu B. Extensive alterations in DNA methylation and transcription in rice caused by introgression from Zizania latifolia. PLANT MOLECULAR BIOLOGY 2004; 54:571-82. [PMID: 15316290 DOI: 10.1023/b:plan.0000038270.48326.7a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
It has been demonstrated that insertion of foreign DNA into mammalian genome can profoundly alter the patterns of DNA methylation and transcription of the host genome. Introgression of alien DNA into plant genomes through sexual crossing and genetic engineering are commonly used in breeding, but it is not known if plant genomes have similar responses to alien DNA introgression as those of animals. Two stable rice lines with introgression from wild rice, Zizania latifolia, were analyzed for patterns of cytosine DNA methylation and transcription of a set of selected sequences, including cellular genes and transposable element (TE)-related DNA segments. In 21 of the 30 studied sequences, marked changes in DNA methylation and/or transcription were observed compared with those of the rice parent. In all analyzed sequences, the absence of Zizania homologues in the introgression lines was confirmed. No change in DNA methylation and expression patterns was detected in randomly selected individuals of the rice parent nor in two sibling lines without introgressed Zizania DNA. The changed methylation patterns in both introgression lines were stably maintained in all five randomly sampled individuals of a given line, as well as in selfed progenies of the lines. Changed patterns in methylation and expression were also found in an independently produced asymmetric somatic nuclear hybrid (SH6) of rice and Z. latifolia that involves a different rice genotype but also contains a small amount of Z. latifolia DNA integrated into the rice genome. Thus, we have demonstrated that alien DNA introgression into a plant genome can induce extensive alterations in DNA methylation and transcription of both cellular genes and TE-related DNA segments in a genotype-independent manner.
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Affiliation(s)
- Zhenlan Liu
- Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun 130024, China
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Abstract
In many eukaryotes, including plants, DNA methylation provides a heritable mark that guides formation of transcriptionally silent heterochromatin. In plants, aberrant RNA signals direct DNA methylation to target sequences, sometimes appropriately and sometimes inappropriately. This chapter discusses the generation of RNA signals for epigenetic changes, the factors that mediate those changes, and some of the consequences of those changes for plant gene expression and genome integrity.
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Affiliation(s)
- Judith Bender
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health , 615 N. Wolfe St., Baltimore, Maryland 21205, USA.
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Melquist S, Bender J. Transcription from an upstream promoter controls methylation signaling from an inverted repeat of endogenous genes in Arabidopsis. Genes Dev 2003; 17:2036-47. [PMID: 12893775 PMCID: PMC196257 DOI: 10.1101/gad.1081603] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In plants, replication of RNA viruses and RNA from highly transcribed transgenes can trigger DNA methylation. These systems accumulate diced small RNA(smRNA) products of double-stranded RNA(dsRNA) precursors, but it is not known which RNA species directs methylation. The methylated PAI tryptophan biosynthetic genes in Arabidopsis allow the study of methylation signals for endogenous genes with lower expression levels. The PAI genes are arranged as a tandem inverted repeat plus two singlet genes at unlinked loci. Here we show that the predominant PAI transcript initiates at a novel unmethylated promoter that lies upstream of one of the inverted repeat PAI genes. Suppressed transcription from the upstream promoter using transgene-directed silencing reduces methylation on the singlet PAI genes, but not on the inverted repeat, consistent with an RNA methylation signal. RNA gel blots detect normal PAI transcripts and dsRNA read-through species, but not diced smRNAs, suggesting that either precursor dsRNAs or subdetectable levels of smRNAs, below the threshold to effectively degrade PAI transcripts, serve as the PAI methylation signal. Thus, the lower expression endogenous gene system allows dissection of a RNA-directed methylation pathway distinct from RNA degradation pathways.
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MESH Headings
- Arabidopsis/genetics
- DNA Methylation
- Gene Expression Regulation, Plant
- Gene Silencing
- Genes, Plant
- Genes, Reporter
- Mutation
- Plants, Genetically Modified
- Promoter Regions, Genetic/genetics
- RNA, Double-Stranded/genetics
- RNA, Double-Stranded/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Small Nuclear/genetics
- RNA, Small Nuclear/metabolism
- Repetitive Sequences, Nucleic Acid/genetics
- Signal Transduction
- Transcription, Genetic/genetics
- Transgenes
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Affiliation(s)
- Stacey Melquist
- Department of Biochemistry and Molecular Biology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
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Comai L, Madlung A, Josefsson C, Tyagi A. Do the different parental 'heteromes' cause genomic shock in newly formed allopolyploids? Philos Trans R Soc Lond B Biol Sci 2003; 358:1149-55. [PMID: 12831481 PMCID: PMC1693194 DOI: 10.1098/rstb.2003.1305] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Allopolyploidy, the joining of two parental genomes in a polyploid organism with diploid meiosis, is an important mechanism of reticulate evolution. While many successful long-established allopolyploids are known, those formed recently undergo an instability phase whose basis is now being characterized. We describe observations made with the Arabidopsis system that include phenotypic instability, gene silencing and activation, and methylation changes. We present a model based on the epigenetic destabilization of genomic repeats, which in the parents are heterochromatinized and suppressed. We hypothesize that loss of epigenetic suppression of these sequences, here defined as the heterome, results in genomic instability including silencing of single-copy genes.
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Affiliation(s)
- Luca Comai
- Department of Biology, Box 355325, University of Washington, Seattle, WA 98195-5325, USA.
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Quiel JA, Bender J. Glucose conjugation of anthranilate by the Arabidopsis UGT74F2 glucosyltransferase is required for tryptophan mutant blue fluorescence. J Biol Chem 2003; 278:6275-81. [PMID: 12475971 DOI: 10.1074/jbc.m211822200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plant mutants with defects in intermediate enzymes of the tryptophan biosynthetic pathway often display a blue fluorescent phenotype. This phenotype results from the accumulation of the fluorescent tryptophan precursor anthranilate, the bulk of which is found in a glucose-conjugated form. To elucidate factors that control fluorescent tryptophan metabolites, we conducted a genetic screen for suppressors of blue fluorescence in the Arabidopsis trp1-100 mutant, which has a defect in the second enzymatic step of the tryptophan pathway. This screen yielded loss-of-function mutations in the UDP-glucosyltransferase gene UGT74F2. The bacterially expressed UGT74F2 enzyme catalyzed a conjugation reaction, with free anthranilate and UDP-glucose as substrates, that yielded the same fluorescent glucose ester compound as extracted from the trp1-100 mutant. These results indicate that sugar conjugation of anthranilate by UGT74F2 allows its stable accumulation in plant tissues. A highly related Arabidopsis enzyme UGT74F1 could also catalyze this reaction in vitro and could complement the ugt74F2 mutation when overexpressed in vivo. However, the UGT74F1 gene is expressed at a lower level than the UGT74F2 gene. Therefore, even though UGT74F1 and UGT74F2 have redundant conjugating activities toward anthranilate, UGT74F2 is the major source of this activity in the plant.
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Affiliation(s)
- Juan A Quiel
- Department of Biochemistry and Molecular Biology, the Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205, USA
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Kakutani T. Epi-alleles in plants: inheritance of epigenetic information over generations. PLANT & CELL PHYSIOLOGY 2002; 43:1106-11. [PMID: 12407189 DOI: 10.1093/pcp/pcf131] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Epigenetic modification of plant gene and transposon activity, which correlates with their methylation, is often heritable over many generations. Such heritable properties allow conventional genetic linkage analysis to identify the sequences affected in epigenetic variants. Machinery controlling the establishment of the epigenetic state and role of the epigenetic controls in plant development are also discussed.
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Affiliation(s)
- Tetsuji Kakutani
- National Institute of Genetics, Mishima, Shizuoka, 411-8540 Japan.
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