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Ren Z, Gou R, Zhuo W, Chen Z, Yin X, Cao Y, Wang Y, Mi Y, Liu Y, Wang Y, Fan LM, Deng XW, Qian W. The MBD-ACD DNA methylation reader complex recruits MICRORCHIDIA6 to regulate ribosomal RNA gene expression in Arabidopsis. Plant Cell 2024; 36:1098-1118. [PMID: 38092516 PMCID: PMC10980342 DOI: 10.1093/plcell/koad313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 12/11/2023] [Indexed: 04/01/2024]
Abstract
DNA methylation is an important epigenetic mark implicated in selective rRNA gene expression, but the DNA methylation readers and effectors remain largely unknown. Here, we report a protein complex that reads DNA methylation to regulate variant-specific 45S ribosomal RNA (rRNA) gene expression in Arabidopsis (Arabidopsis thaliana). The complex, consisting of METHYL-CpG-BINDING DOMAIN PROTEIN5 (MBD5), MBD6, ALPHA-CRYSTALLIN DOMAIN PROTEIN15.5 (ACD15.5), and ACD21.4, directly binds to 45S rDNA. While MBD5 and MBD6 function redundantly, ACD15.5 and ACD21.4 are indispensable for variant-specific rRNA gene expression. These 4 proteins undergo phase separation in vitro and in vivo and are interdependent for their phase separation. The α-crystallin domain of ACD15.5 and ACD21.4, which is essential for their function, enables phase separation of the complex, likely by mediating multivalent protein interactions. The effector MICRORCHIDIA6 directly interacts with ACD15.5 and ACD21.4, but not with MBD5 and MBD6, and is recruited to 45S rDNA by the MBD-ACD complex to regulate variant-specific 45S rRNA expression. Our study reveals a pathway in Arabidopsis through which certain 45S rRNA gene variants are silenced, while others are activated.
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Affiliation(s)
- Zhitong Ren
- National Key Laboratory of Wheat Improvement, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Peking University Institute of advanced Agricultural Sciences, Weifang, Shandong 261325, China
- College of Agronomy, Sichuan Agriculture University, Chengdu 611130, China
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Runyu Gou
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Wanqing Zhuo
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Zhiyu Chen
- State Key Laboratory of Genetic Engineering and Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Xiaochang Yin
- National Key Laboratory of Wheat Improvement, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Peking University Institute of advanced Agricultural Sciences, Weifang, Shandong 261325, China
| | - Yuxin Cao
- National Key Laboratory of Wheat Improvement, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Peking University Institute of advanced Agricultural Sciences, Weifang, Shandong 261325, China
| | - Yue Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Yingjie Mi
- National Key Laboratory of Wheat Improvement, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Peking University Institute of advanced Agricultural Sciences, Weifang, Shandong 261325, China
| | - Yannan Liu
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Yingxiang Wang
- State Key Laboratory of Genetic Engineering and Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200438, China
- College of Life Sciences, Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Liu-Min Fan
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Xing Wang Deng
- National Key Laboratory of Wheat Improvement, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Peking University Institute of advanced Agricultural Sciences, Weifang, Shandong 261325, China
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Weiqiang Qian
- National Key Laboratory of Wheat Improvement, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Peking University Institute of advanced Agricultural Sciences, Weifang, Shandong 261325, China
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
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Shatskikh AS, Fefelova EA, Klenov MS. Functions of RNAi Pathways in Ribosomal RNA Regulation. Noncoding RNA 2024; 10:19. [PMID: 38668377 DOI: 10.3390/ncrna10020019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/19/2024] [Accepted: 03/27/2024] [Indexed: 04/29/2024] Open
Abstract
Argonaute proteins, guided by small RNAs, play crucial roles in gene regulation and genome protection through RNA interference (RNAi)-related mechanisms. Ribosomal RNAs (rRNAs), encoded by repeated rDNA units, constitute the core of the ribosome being the most abundant cellular transcripts. rDNA clusters also serve as sources of small RNAs, which are loaded into Argonaute proteins and are able to regulate rDNA itself or affect other gene targets. In this review, we consider the impact of small RNA pathways, specifically siRNAs and piRNAs, on rRNA gene regulation. Data from diverse eukaryotic organisms suggest the potential involvement of small RNAs in various molecular processes related to the rDNA transcription and rRNA fate. Endogenous siRNAs are integral to the chromatin-based silencing of rDNA loci in plants and have been shown to repress rDNA transcription in animals. Small RNAs also play a role in maintaining the integrity of rDNA clusters and may function in the cellular response to rDNA damage. Studies on the impact of RNAi and small RNAs on rRNA provide vast opportunities for future exploration.
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Affiliation(s)
- Aleksei S Shatskikh
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilov Street, 119334 Moscow, Russia
| | - Elena A Fefelova
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182 Moscow, Russia
| | - Mikhail S Klenov
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182 Moscow, Russia
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, 368 Plantation Street, Worcester, MA 01605, USA
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Shanmugam T, Chaturvedi P, Streit D, Ghatak A, Bergelt T, Simm S, Weckwerth W, Schleiff E. Low dose ribosomal DNA P-loop mutation affects development and enforces autophagy in Arabidopsis. RNA Biol 2024; 21:1-15. [PMID: 38156797 PMCID: PMC10761087 DOI: 10.1080/15476286.2023.2298532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2023] [Indexed: 01/03/2024] Open
Abstract
Arabidopsis contains hundreds of ribosomal DNA copies organized within the nucleolar organizing regions (NORs) in chromosomes 2 and 4. There are four major types of variants of rDNA, VAR1-4, based on the polymorphisms of 3' external transcribed sequences. The variants are known to be differentially expressed during plant development. We created a mutant by the CRISPR-Cas9-mediated excision of ~ 25 nt from predominantly NOR4 ribosomal DNA copies, obtaining mosaic mutational events on ~ 5% of all rDNA copies. The excised region consists of P-loop and Helix-82 segments of 25S rRNA. The mutation led to allelic, dosage-dependent defects marked by lateral root inhibition, reduced size, and pointy leaves, all previously observed for defective ribosomal function. The mutation in NOR4 led to dosage compensation from the NOR2 copies by elevated expression of VAR1 in mutants and further associated single-nucleotide variants, thus, resulting in altered rRNA sub-population. Furthermore, the mutants exhibited rRNA maturation defects specifically in the minor pathway typified by 32S pre-rRNA accumulation. Density-gradient fractionation and subsequent RT-PCR of rRNA analyses revealed that mutated copies were not incorporated into the translating ribosomes. The mutants in addition displayed an elevated autophagic flux as shown by the autophagic marker GFP-ATG8e, likely related to ribophagy.
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Affiliation(s)
- Thiruvenkadam Shanmugam
- Molecular Cell Biology of Plants, Institute for Molecular Biosciences & Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Palak Chaturvedi
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Deniz Streit
- Molecular Cell Biology of Plants, Institute for Molecular Biosciences & Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Arindam Ghatak
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Thorsten Bergelt
- Molecular Cell Biology of Plants, Institute for Molecular Biosciences & Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Stefan Simm
- Molecular Cell Biology of Plants, Institute for Molecular Biosciences & Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
- Institute of Bioinformatics, University Medicine Greifswald, Greifswald, Germany
| | - Wolfram Weckwerth
- Molecular Systems Biology (MOSYS), Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
- Vienna Metabolomics Center (VIME), University of Vienna, Vienna, Austria
| | - Enrico Schleiff
- Molecular Cell Biology of Plants, Institute for Molecular Biosciences & Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
- Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany
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Priyadarshini N, Venkatarama Puppala N, Jayaprakash JP, Khandelia P, Sharma V, Mohannath G. Downregulation of ribosomal RNA (rRNA) genes in human head and neck squamous cell carcinoma (HNSCC) cells correlates with rDNA promoter hypermethylation. Gene 2023; 888:147793. [PMID: 37696422 DOI: 10.1016/j.gene.2023.147793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/31/2023] [Accepted: 09/08/2023] [Indexed: 09/13/2023]
Abstract
Eukaryotes carry hundreds of ribosomal RNA (rRNA) genes as tandem arrays, which generate rRNA for protein synthesis. Humans carry ∼ 400 rRNA gene copies and their expression is epigenetically regulated. Dysregulation of rRNA synthesis and ribosome biogenesis are characteristic features of cancers. Targeting aberrant rRNA expression for cancer therapy is being explored. Head and neck squamous cell carcinoma (HNSCC) is among the most prevalent cancers globally. Using quantitative PCR and bisulfite sequencing, we show that rRNA genes are downregulated and their promoters are hypermethylated in HNSCC cell lines. These findings may have relevance for prognosis and diagnosis of HNSCC.
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Affiliation(s)
- Neha Priyadarshini
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, India.
| | - Navinchandra Venkatarama Puppala
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, India.
| | - Jayasree Peroth Jayaprakash
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, India.
| | - Piyush Khandelia
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, India.
| | - Vivek Sharma
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, India.
| | - Gireesha Mohannath
- Department of Biological Sciences, Birla Institute of Technology & Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, India.
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Fultz D, McKinlay A, Enganti R, Pikaard CS. Sequence and epigenetic landscapes of active and silent nucleolus organizer regions in Arabidopsis. Sci Adv 2023; 9:eadj4509. [PMID: 37910609 PMCID: PMC10619934 DOI: 10.1126/sciadv.adj4509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 09/27/2023] [Indexed: 11/03/2023]
Abstract
Arabidopsis thaliana has two ribosomal RNA (rRNA) gene loci, nucleolus organizer regions NOR2 and NOR4, whose complete sequences are missing in current genome assemblies. Ultralong DNA sequences assembled using an unconventional approach yielded ~5.5- and 3.9-Mbp sequences for NOR2 and NOR4 in the reference strain, Col-0. The distinct rRNA gene subtype compositions of the NORs enabled the positional mapping of their active and inactive regions, using RNA sequencing to identify subtype-specific transcripts and DNA sequencing to identify subtypes associated with flow-sorted nucleoli. Comparisons of wild-type and silencing-defective plants revealed that most rRNA gene activity occurs in the central region of NOR4, whereas most, but not all, genes of NOR2 are epigenetically silenced. Intervals of low CG and CHG methylation overlap regions where gene activity and gene subtype homogenization are high. Collectively, the data reveal the genetic and epigenetic landscapes underlying nucleolar dominance (differential NOR activity) and implicate transcription as a driver of rRNA gene concerted evolution.
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Affiliation(s)
- Dalen Fultz
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, USA
- Department of Biology, Indiana University, Bloomington, IN, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Anastasia McKinlay
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, USA
- Department of Biology, Indiana University, Bloomington, IN, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Ramya Enganti
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, USA
- Department of Biology, Indiana University, Bloomington, IN, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Craig S. Pikaard
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, USA
- Department of Biology, Indiana University, Bloomington, IN, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
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6
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Ando S, Nomoto M, Iwakawa H, Vial-Pradel S, Luo L, Sasabe M, Ohbayashi I, Yamamoto KT, Tada Y, Sugiyama M, Machida Y, Kojima S, Machida C. Arabidopsis ASYMMETRIC LEAVES2 and Nucleolar Factors Are Coordinately Involved in the Perinucleolar Patterning of AS2 Bodies and Leaf Development. Plants (Basel) 2023; 12:3621. [PMID: 37896084 PMCID: PMC10610122 DOI: 10.3390/plants12203621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/09/2023] [Accepted: 10/13/2023] [Indexed: 10/29/2023]
Abstract
Arabidopsis ASYMMETRIC LEAVES2 (AS2) plays a key role in the formation of flat symmetric leaves. AS2 represses the expression of the abaxial gene ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3). AS2 interacts in vitro with the CGCCGC sequence in ETT/ARF3 exon 1. In cells of leaf primordia, AS2 localizes at peripheral regions of the nucleolus as two AS2 bodies, which are partially overlapped with chromocenters that contain condensed 45S ribosomal DNA repeats. AS2 contains the AS2/LOB domain, which consists of three sequences conserved in the AS2/LOB family: the zinc finger (ZF) motif, the ICG sequence including the conserved glycine residue, and the LZL motif. AS2 and the genes NUCLEOLIN1 (NUC1), RNA HELICASE10 (RH10), and ROOT INITIATION DEFECTIVE2 (RID2) that encode nucleolar proteins coordinately act as repressors against the expression of ETT/ARF3. Here, we examined the formation and patterning of AS2 bodies made from as2 mutants with amino acid substitutions in the ZF motif and the ICG sequence in cells of cotyledons and leaf primordia. Our results showed that the amino acid residues next to the cysteine residues in the ZF motif were essential for both the formation of AS2 bodies and the interaction with ETT/ARF3 DNA. The conserved glycine residue in the ICG sequence was required for the formation of AS2 bodies, but not for the DNA interaction. We also examined the effects of nuc1, rh10, and rid2 mutations, which alter the metabolism of rRNA intermediates and the morphology of the nucleolus, and showed that more than two AS2 bodies were observed in the nucleolus and at its periphery. These results suggested that the patterning of AS2 bodies is tightly linked to the morphology and functions of the nucleolus and the development of flat symmetric leaves in plants.
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Affiliation(s)
- Sayuri Ando
- Graduate School of Bioscience and Biotechnology, Chubu University, Kasugai 487-8501, Japan; (S.A.); (H.I.); (S.V.-P.); (Y.M.)
| | - Mika Nomoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan; (M.N.); (L.L.); (Y.T.)
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
| | - Hidekazu Iwakawa
- Graduate School of Bioscience and Biotechnology, Chubu University, Kasugai 487-8501, Japan; (S.A.); (H.I.); (S.V.-P.); (Y.M.)
| | - Simon Vial-Pradel
- Graduate School of Bioscience and Biotechnology, Chubu University, Kasugai 487-8501, Japan; (S.A.); (H.I.); (S.V.-P.); (Y.M.)
| | - Lilan Luo
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan; (M.N.); (L.L.); (Y.T.)
| | - Michiko Sasabe
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Bunkyo-cho, Hirosaki 036-8561, Japan;
| | - Iwai Ohbayashi
- Department of Life Sciences, National Cheng Kung University, Tainan City 701, Taiwan;
| | - Kotaro T. Yamamoto
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Yasuomi Tada
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan; (M.N.); (L.L.); (Y.T.)
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
| | - Munetaka Sugiyama
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan;
| | - Yasunori Machida
- Graduate School of Bioscience and Biotechnology, Chubu University, Kasugai 487-8501, Japan; (S.A.); (H.I.); (S.V.-P.); (Y.M.)
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan; (M.N.); (L.L.); (Y.T.)
| | - Shoko Kojima
- Graduate School of Bioscience and Biotechnology, Chubu University, Kasugai 487-8501, Japan; (S.A.); (H.I.); (S.V.-P.); (Y.M.)
| | - Chiyoko Machida
- Graduate School of Bioscience and Biotechnology, Chubu University, Kasugai 487-8501, Japan; (S.A.); (H.I.); (S.V.-P.); (Y.M.)
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7
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Mahelka V, Kopecký D, Majka J, Krak K. Uniparental expression of ribosomal RNA in × Festulolium grasses: a link between the genome and nucleolar dominance. Front Plant Sci 2023; 14:1276252. [PMID: 37790792 PMCID: PMC10544908 DOI: 10.3389/fpls.2023.1276252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 08/30/2023] [Indexed: 10/05/2023]
Abstract
Genome or genomic dominance (GD) is a phenomenon observed in hybrids when one parental genome becomes dominant over the other. It is manifested by the replacement of chromatin of the submissive genome by that of the dominant genome and by biased gene expression. Nucleolar dominance (ND) - the functional expression of only one parental set of ribosomal genes in hybrids - is another example of an intragenomic competitive process which, however, concerns ribosomal DNA only. Although GD and ND are relatively well understood, the nature and extent of their potential interdependence is mostly unknown. Here, we ask whether hybrids showing GD also exhibit ND and, if so, whether the dominant genome is the same. To test this, we used hybrids between Festuca and Lolium grasses (Festulolium), and between two Festuca species in which GD has been observed (with Lolium as the dominant genome in Festulolium and F. pratensis in interspecific Festuca hybrids). Using amplicon sequencing of ITS1 and ITS2 of the 45S ribosomal DNA (rDNA) cluster and molecular cytogenetics, we studied the organization and expression of rDNA in leaf tissue in five hybrid combinations, four generations and 31 genotypes [F. pratensis × L. multiflorum (F1, F2, F3, BC1), L. multiflorum × F. pratensis (F1), L. multiflorum × F. glaucescens (F2), L. perenne × F. pratensis (F1), F. glaucescens × F. pratensis (F1)]. We have found that instant ND occurs in Festulolium, where expression of Lolium-type rDNA reached nearly 100% in all F1 hybrids and was maintained through subsequent generations. Therefore, ND and GD in Festulolium are manifested by the same dominant genome (Lolium). We also confirmed the concordance between GD and ND in an interspecific cross between two Festuca species.
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Affiliation(s)
- Václav Mahelka
- Czech Academy of Sciences, Institute of Botany, Průhonice, Czechia
| | - David Kopecký
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of Plant Structural and Functional Genomics, Olomouc, Czechia
| | - Joanna Majka
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of Plant Structural and Functional Genomics, Olomouc, Czechia
| | - Karol Krak
- Czech Academy of Sciences, Institute of Botany, Průhonice, Czechia
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Prague, Czechia
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Huang Y, Liu Y, Guo X, Fan C, Yi C, Shi Q, Su H, Liu C, Yuan J, Liu D, Yang W, Han F. New insights on the evolution of nucleolar dominance in newly resynthesized hexaploid wheat Triticum zhukovskyi. Plant J 2023; 115:1298-1315. [PMID: 37246611 DOI: 10.1111/tpj.16320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/11/2023] [Accepted: 05/23/2023] [Indexed: 05/30/2023]
Abstract
Nucleolar dominance (ND) is a widespread epigenetic phenomenon in hybridizations where nucleolus transcription fails at the nucleolus organizer region (NOR). However, the dynamics of NORs during the formation of Triticum zhukovskyi (GGAu Au Am Am ), another evolutionary branch of allohexaploid wheat, remains poorly understood. Here, we elucidated genetic and epigenetic changes occurring at the NOR loci within the Am , G, and D subgenomes during allopolyploidization by synthesizing hexaploid wheat GGAu Au Am Am and GGAu Au DD. In T. zhukovskyi, Au genome NORs from T. timopheevii (GGAu Au ) were lost, while the second incoming NORs from T. monococcum (Am Am ) were retained. Analysis of the synthesized T. zhukovskyi revealed that rRNA genes from the Am genome were silenced in F1 hybrids (GAu Am ) and remained inactive after genome doubling and subsequent self-pollinations. We observed increased DNA methylation accompanying the inactivation of NORs in the Am genome and found that silencing of NORs in the S1 generation could be reversed by a cytidine methylase inhibitor. Our findings provide insights into the ND process during the evolutionary period of T. zhukovskyi and highlight that inactive rDNA units may serve as a 'first reserve' in the form of R-loops, contributing to the successful evolution of T. zhukovskyi.
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Affiliation(s)
- Yuhong Huang
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yang Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xianrui Guo
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Chaolan Fan
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Congyang Yi
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qinghua Shi
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Handong Su
- Huazhong Agricultural University, Hubei, 430070, China
| | - Chang Liu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jing Yuan
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Dengcai Liu
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, 611130, China
| | - Wuyun Yang
- Crop Research Institute, Sichuan Academy of Agricultural Sciences, Chengdu, 610066, China
| | - Fangpu Han
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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9
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Pikaard CS, Chandrasekhara C, McKinlay A, Enganti R, Fultz D. Reaching for the off switch in nucleolar dominance. Plant J 2023; 115:1185-1192. [PMID: 37228042 PMCID: PMC10524600 DOI: 10.1111/tpj.16318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/18/2023] [Accepted: 05/23/2023] [Indexed: 05/27/2023]
Abstract
Nucleolus organizer regions (NORs) are eukaryotic chromosomal loci where ribosomal RNA (rRNA) genes are clustered, typically in hundreds to thousands of copies. Transcription of these rRNA genes by RNA polymerase I and processing of their transcripts results in the formation of the nucleolus, the sub-nuclear domain in which ribosomes are assembled. Approximately 90 years ago, cytogenetic observations revealed that NORs inherited from the different parents of an interspecific hybrid sometimes differ in morphology at metaphase. Fifty years ago, those chromosomal differences were found to correlate with differences in rRNA gene transcription and the phenomenon became known as nucleolar dominance. Studies of the past 30 years have revealed that nucleolar dominance results from selective rRNA gene silencing, involving repressive chromatin modifications, and occurs in pure species as well as hybrids. Recent evidence also indicates that silencing depends on the NOR in which an rRNA gene is located, and not on the gene's sequence. In this perspective, we discuss how our thinking about nucleolar dominance has shifted over time from the kilobase scale of individual genes to the megabase scale of NORs and chromosomes and questions that remain unanswered in the search for a genetic and biochemical understanding of the off switch.
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Affiliation(s)
- Craig S Pikaard
- Department of Biology, Indiana University, Bloomington, Indiana, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
- Howard Hughes Medical Institute, Indiana University, Bloomington, Indiana, USA
| | - Chinmayi Chandrasekhara
- Department of Biology, Indiana University, Bloomington, Indiana, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
| | - Anastasia McKinlay
- Department of Biology, Indiana University, Bloomington, Indiana, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
- Howard Hughes Medical Institute, Indiana University, Bloomington, Indiana, USA
| | - Ramya Enganti
- Department of Biology, Indiana University, Bloomington, Indiana, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
- Howard Hughes Medical Institute, Indiana University, Bloomington, Indiana, USA
| | - Dalen Fultz
- Department of Biology, Indiana University, Bloomington, Indiana, USA
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana, USA
- Howard Hughes Medical Institute, Indiana University, Bloomington, Indiana, USA
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10
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Delorme-Hinoux V, Mbodj A, Brando S, De Bures A, Llauro C, Covato F, Garrigue J, Guisset C, Borrut J, Mirouze M, Reichheld JP, Sáez-Vásquez J. 45S rDNA Diversity In Natura as One Step towards Ribosomal Heterogeneity in Arabidopsis thaliana. Plants (Basel) 2023; 12:2722. [PMID: 37514338 PMCID: PMC10386311 DOI: 10.3390/plants12142722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023]
Abstract
The keystone of ribosome biogenesis is the transcription of 45S rDNA. The Arabidopsis thaliana genome contains hundreds of 45S rDNA units; however, they are not all transcribed. Notably, 45S rDNA units contain insertions/deletions revealing the existence of heterogeneous rRNA genes and, likely, heterogeneous ribosomes for rRNAs. In order to obtain an overall picture of 45S rDNA diversity sustaining the synthesis of rRNAs and, subsequently, of ribosomes in natura, we took advantage of 320 new occurrences of Arabidopsis thaliana as a metapopulation named At66, sampled from 0 to 1900 m of altitude in the eastern Pyrenees in France. We found that the 45S rDNA copy number is very dynamic in natura and identified new genotypes for both 5' and 3' External Transcribed Spacers (ETS). Interestingly, the highest 5'ETS genotype diversity is found in altitude while the highest 3'ETS genotype diversity is found at sea level. Structural analysis of 45S rDNA also shows conservation in natura of specific 5'ETS and 3'ETS sequences/features required to control rDNA expression and the processing of rRNAs. In conclusion, At66 is a worthwhile natural laboratory, and unraveled 45S rDNA diversity represents an interesting starting material to select subsets for rDNA transcription and alter the rRNA composition of ribosomes both intra- and inter-site.
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Affiliation(s)
- Valérie Delorme-Hinoux
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- EMR LGDP/MANGO, Mechanisms of Adaptation and Genomics, IRD-CNRS-UPVD, 66860 Perpignan, France
- Association Charles Flahault, 66350 Toulouges, France
| | - Assane Mbodj
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- EMR LGDP/MANGO, Mechanisms of Adaptation and Genomics, IRD-CNRS-UPVD, 66860 Perpignan, France
- Institut de Recherche pour le Développement (IRD), ECOBIO, 34000 Montpellier, France
| | - Sophie Brando
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
| | - Anne De Bures
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
| | - Christel Llauro
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- EMR LGDP/MANGO, Mechanisms of Adaptation and Genomics, IRD-CNRS-UPVD, 66860 Perpignan, France
| | - Fabrice Covato
- FRNC, Fédération des Réserves Naturelles Catalanes, 66500 Prades, France
| | - Joseph Garrigue
- FRNC, Fédération des Réserves Naturelles Catalanes, 66500 Prades, France
| | - Claude Guisset
- Association Charles Flahault, 66350 Toulouges, France
- FRNC, Fédération des Réserves Naturelles Catalanes, 66500 Prades, France
| | | | - Marie Mirouze
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- EMR LGDP/MANGO, Mechanisms of Adaptation and Genomics, IRD-CNRS-UPVD, 66860 Perpignan, France
- Institut de Recherche pour le Développement (IRD), ECOBIO, 34000 Montpellier, France
| | - Jean-Philippe Reichheld
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
| | - Julio Sáez-Vásquez
- Université de Perpignan Via Domitia (UPVD), Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
- Centre National de la Recherche Scientifique, Laboratoire Génome et Développement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France
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11
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Borowska-Zuchowska N, Mykhailyk S, Robaszkiewicz E, Matysiak N, Mielanczyk L, Wojnicz R, Kovarik A, Hasterok R. Switch them off or not: selective rRNA gene repression in grasses. Trends Plant Sci 2023; 28:661-672. [PMID: 36764871 DOI: 10.1016/j.tplants.2023.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/31/2022] [Accepted: 01/11/2023] [Indexed: 05/13/2023]
Abstract
Nucleolar dominance (ND) is selective epigenetic silencing of 35-48S rDNA loci. In allopolyploids, it is frequently manifested at the cytogenetic level by the inactivation of nucleolar organiser region(s) (NORs) inherited from one or several evolutionary ancestors. Grasses are ecologically and economically one of the most important land plant groups, which have frequently evolved through hybridisation and polyploidisation events. Here we review common and unique features of ND phenomena in this monocot family from cytogenetic, molecular, and genomic perspectives. We highlight recent advances achieved by using an allotetraploid model grass, Brachypodium hybridum, where ND commonly occurs at a population level, and we cover modern genomic approaches that decipher structural features of core arrays of NORs.
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Affiliation(s)
- Natalia Borowska-Zuchowska
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice 40-032, Poland.
| | - Serhii Mykhailyk
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice 40-032, Poland
| | - Ewa Robaszkiewicz
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice 40-032, Poland
| | - Natalia Matysiak
- Department of Histology and Cell Pathology, the Medical University of Silesia in Katowice, School of Medicine with the Division of Dentistry, Zabrze, Poland
| | - Lukasz Mielanczyk
- Department of Histology and Cell Pathology, the Medical University of Silesia in Katowice, School of Medicine with the Division of Dentistry, Zabrze, Poland; Silesian Nanomicroscopy Centre in Zabrze, Silesia LabMed - Research and Implementation Centre, Medical University of Silesia, Katowice, Poland
| | - Romuald Wojnicz
- Department of Histology and Cell Pathology, the Medical University of Silesia in Katowice, School of Medicine with the Division of Dentistry, Zabrze, Poland; Silesian Nanomicroscopy Centre in Zabrze, Silesia LabMed - Research and Implementation Centre, Medical University of Silesia, Katowice, Poland
| | - Ales Kovarik
- Department of Molecular Epigenetics, Institute of Biophysics, Czech Academy of Sciences, CZ-61200 Brno, Czech Republic
| | - Robert Hasterok
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice 40-032, Poland.
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12
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Ding X, Chen J, Dai C, Shi P, Pan H, Lin Y, Chen Y, Gong L, Chen L, Wu W, Qiu X, Xu J, Huang Z, Liao B. Developing population identification tool based on polymorphism of rDNA for traditional Chinese medicine: Artemisia annua L. Phytomedicine 2023; 116:154882. [PMID: 37210961 DOI: 10.1016/j.phymed.2023.154882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/29/2023] [Accepted: 05/12/2023] [Indexed: 05/23/2023]
Abstract
BACKGROUND Artemisia annua, a well-known traditional Chinese medicine, is the main source for production of artemisinin, an anti-malaria drug. A. annua is distributed globally, with great diversity of morphological characteristics and artemisinin contents. Diverse traits among A. annua populations impeded the stable production of artemisinin, which needs an efficient tool to identify strains and assess population genetic homogeneity. PURPOSE In this study, ribosomal DNA (rDNA), were characterized for A. annua for strains identification and population genetic homogeneity assessment. METHODS The ribosomal RNA (rRNA) genes were identified using cmscan and assembled using rDNA unit of LQ-9 as a reference. rDNA among Asteraceae species were compared performing with 45S rDNA. The rDNA copy number was calculated based on sequencing depth. The polymorphisms of rDNA sequences were identified with bam-readcount, and confirmed by Sanger sequencing and restriction enzyme experiment. The ITS2 amplicon sequencing was used to verify the stability of ITS2 haplotype analysis. RESULTS Different from other Asteraceae species, 45S and 5S linked-type rDNA was only found in Artemisia genus. Rich polymorphisms of copy number and sequence of rDNA were identified in A. annua population. The haplotype composition of internal transcribed spacer 2 (ITS2) region which had moderate sequence polymorphism and relative short size was significantly different among A. annua strains. A population discrimination method was developed based on ITS2 haplotype analysis with high-throughput sequencing. CONCLUSION This study provides comprehensive characteristics of rDNA and suggests that ITS2 haplotype analysis is ideal tool for A. annua strain identification and population genetic homogeneity assessment.
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Affiliation(s)
- Xiaoxia Ding
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Jieting Chen
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Chunyan Dai
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Peiqi Shi
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Hengyu Pan
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Yanqi Lin
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Yikang Chen
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Lu Gong
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Linming Chen
- Guangzhou Huibiao Testing Technology Center, Guangzhou 510700, China
| | - Wenguang Wu
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Xiaohui Qiu
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China
| | - Jiang Xu
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing 100700, China.
| | - Zhihai Huang
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China.
| | - Baosheng Liao
- Key Laboratory of Quality Evaluation of Chinese Medicine of the Guangdong Provincial Medical Products Administration, the Second Clinical College, Guangzhou University of Chinese Medicine, Guangzhou 510006, China.
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13
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Morton EA, Hall AN, Cuperus JT, Queitsch C. Substantial rDNA copy number reductions alter timing of development and produce variable tissue-specific phenotypes in C. elegans. Genetics 2023; 224:iyad039. [PMID: 36919976 PMCID: PMC10474940 DOI: 10.1093/genetics/iyad039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/01/2023] [Accepted: 03/02/2023] [Indexed: 03/16/2023] Open
Abstract
The genes that encode ribosomal RNAs are present in several hundred copies in most eukaryotes. These vast arrays of repetitive ribosomal DNA (rDNA) have been implicated not just in ribosome biogenesis, but also aging, cancer, genome stability, and global gene expression. rDNA copy number is highly variable among and within species; this variability is thought to associate with traits relevant to human health and disease. Here we investigate the phenotypic consequences of multicellular life at the lower bounds of rDNA copy number. We use the model Caenorhabditis elegans, which has previously been found to complete embryogenesis using only maternally provided ribosomes. We find that individuals with rDNA copy number reduced to ∼5% of wild type are capable of further development with variable penetrance. Such individuals are sterile and exhibit severe morphological defects, particularly in post-embryonically dividing tissues such as germline and vulva. Developmental completion and fertility are supported by an rDNA copy number ∼10% of wild type, with substantially delayed development. Worms with rDNA copy number reduced to ∼33% of wild type display a subtle developmental timing defect that was absent in worms with higher copy numbers. Our results support the hypothesis that rDNA requirements vary across tissues and indicate that the minimum rDNA copy number for fertile adulthood is substantially less than the lowest naturally observed total copy number. The phenotype of individuals with severely reduced rDNA copy number is highly variable in penetrance and presentation, highlighting the need for continued investigation into the biological consequences of rDNA copy number variation.
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Affiliation(s)
| | - Ashley N Hall
- Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI 53726, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Josh T Cuperus
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Christine Queitsch
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
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14
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Saradadevi GP, Fultz D, Ramgopal MK, Subramanian AT, Prince G, Thakur V, Mohannath G. Structural variation among assembled genomes facilitates development of rapid and low-cost NOR-linked markers and NOR-telomere junction mapping in Arabidopsis. Plant Cell Rep 2023; 42:1059-1069. [PMID: 37074465 DOI: 10.1007/s00299-023-03012-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 03/27/2023] [Indexed: 05/03/2023]
Abstract
KEY MESSAGE Genome-wide structural variants we identified and new NOR-linked markers we developed would be useful for future genome-wide association studies (GWAS), and for new gene/trait mapping purposes. Bioinformatic alignment of the assembled genomes of Col-0 and Sha ecotypes of Arabidopsis thaliana revealed ~ 13,000 genome-wide structural variants involving simple insertions or deletions and repeat contractions or expansions. Using some of these structural variants, we developed new, rapid, and low-cost PCR-based molecular markers that are genetically linked to the nucleolus organizer regions (NORs). A. thaliana has two NORs, one each on chromosome 2 (NOR2) and chromosome 4 (NOR4). Both NORs are ~ 4 Mb each, and hundreds of 45S ribosomal RNA (rRNA) genes are tandemly arrayed at these loci. Using previously characterized recombinant inbred lines (RILs) derived from Sha x Col-0 crosses, we validated the utility of the newly developed NOR-linked markers in genetically mapping rRNA genes and the associated telomeres to either NOR2 or NOR4. Lastly, we sequenced Sha genome using Oxford Nanopore Technology (ONT) and used the data to obtain sequences of NOR-telomere junctions, and with the help of RILs, we mapped them as new genetic markers to their respective NORs (NOR2-TEL2N and NOR4-TEL4N). The structural variants obtained from this study would serve as valuable data for genome-wide association studies (GWAS), and to rapidly design more genome-wide genetic (molecular) markers for new gene/trait mapping purposes.
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Affiliation(s)
- Gargi Prasad Saradadevi
- Department of Biological Sciences, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, 500078, India
| | - Dalen Fultz
- Department of Biology and Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, 47405, USA
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, 47405, USA
| | - Murali Krishna Ramgopal
- Department of Biological Sciences, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, 500078, India
| | - Abirami T Subramanian
- Department of Biological Sciences, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, 500078, India
| | - Gerin Prince
- Department of Systems and Computational Biology, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Vivek Thakur
- Department of Systems and Computational Biology, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Gireesha Mohannath
- Department of Biological Sciences, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, Telangana, 500078, India.
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15
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Darriere T, Jobet E, Zavala D, Escande ML, Durut N, de Bures A, Blanco-Herrera F, Vidal EA, Rompais M, Carapito C, Gourbiere S, Sáez-Vásquez J. Upon heat stress processing of ribosomal RNA precursors into mature rRNAs is compromised after cleavage at primary P site in Arabidopsis thaliana. RNA Biol 2022; 19:719-734. [PMID: 35522061 PMCID: PMC9090299 DOI: 10.1080/15476286.2022.2071517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Transcription and processing of 45S rRNAs in the nucleolus are keystones of ribosome biogenesis. While these processes are severely impacted by stress conditions in multiple species, primarily upon heat exposure, we lack information about the molecular mechanisms allowing sessile organisms without a temperature-control system, like plants, to cope with such circumstances. We show that heat stress disturbs nucleolar structure, inhibits pre-rRNA processing and provokes imbalanced ribosome profiles in Arabidopsis thaliana plants. Notably, the accuracy of transcription initiation and cleavage at the primary P site in the 5’ETS (5’ External Transcribed Spacer) are not affected but the levels of primary 45S and 35S transcripts are, respectively, increased and reduced. In contrast, precursors of 18S, 5.8S and 25S RNAs are rapidly undetectable upon heat stress. Remarkably, nucleolar structure, pre-rRNAs from major ITS1 processing pathway and ribosome profiles are restored after returning to optimal conditions, shedding light on the extreme plasticity of nucleolar functions in plant cells. Further genetic and molecular analysis to identify molecular clues implicated in these nucleolar responses indicate that cleavage rate at P site and nucleolin protein expression can act as a checkpoint control towards a productive pre-rRNA processing pathway.
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Affiliation(s)
- T Darriere
- CNRS, Laboratoire Génome et D#x0E9;veloppement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France.,Univ. Perpignan Via Domitia, LGDP, UMR 5096, Perpignan, France
| | - E Jobet
- CNRS, Laboratoire Génome et D#x0E9;veloppement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France.,Univ. Perpignan Via Domitia, LGDP, UMR 5096, Perpignan, France
| | - D Zavala
- Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - M L Escande
- CNRS, Observatoire Océanologique de Banyuls s/ mer, Banyuls-sur-mer, France.,BioPIC Platform of the OOB, Banyuls-sur-mer, France
| | - N Durut
- CNRS, Laboratoire Génome et D#x0E9;veloppement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France.,Univ. Perpignan Via Domitia, LGDP, UMR 5096, Perpignan, France
| | - A de Bures
- CNRS, Laboratoire Génome et D#x0E9;veloppement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France.,Univ. Perpignan Via Domitia, LGDP, UMR 5096, Perpignan, France
| | - F Blanco-Herrera
- Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.,Millennium Institute for Integrative Biology (IBio), Santiago, Chile
| | - E A Vidal
- Millennium Institute for Integrative Biology (IBio), Santiago, Chile.,Bioinformática, Facultad de Ciencias, Universidad MayorCentro de Genómica y , Santiago, Chile
| | - M Rompais
- Laboratoire de Spectrométrie de Masse BioOrganique, Institut Pluridisciplinaire Hubert Curien, UMR7178 CNRS/Université de Strasbourg, Strasbourg, France
| | - C Carapito
- Laboratoire de Spectrométrie de Masse BioOrganique, Institut Pluridisciplinaire Hubert Curien, UMR7178 CNRS/Université de Strasbourg, Strasbourg, France
| | - S Gourbiere
- CNRS, Laboratoire Génome et D#x0E9;veloppement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France.,Univ. Perpignan Via Domitia, LGDP, UMR 5096, Perpignan, France
| | - J Sáez-Vásquez
- CNRS, Laboratoire Génome et D#x0E9;veloppement des Plantes (LGDP), UMR 5096, 66860 Perpignan, France.,Univ. Perpignan Via Domitia, LGDP, UMR 5096, Perpignan, France
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16
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Hall AN, Morton E, Queitsch C. First discovered, long out of sight, finally visible: ribosomal DNA. Trends Genet 2022; 38:587-597. [PMID: 35272860 PMCID: PMC10132741 DOI: 10.1016/j.tig.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 10/18/2022]
Abstract
With the advent of long-read sequencing, previously unresolvable genomic elements are being revisited in an effort to generate fully complete reference genomes. One such element is ribosomal DNA (rDNA), the highly conserved genomic region that encodes rRNAs. Genomic structure and content of the rDNA are variable in both prokarya and eukarya, posing interesting questions about the biology of rDNA. Here, we consider the types of variation observed in rDNA - including locus structure and number, copy number, and sequence variation - and their known phenotypic consequences. With recent advances in long-read sequencing technology, incorporating the full rDNA sequence into reference genomes is within reach. This knowledge will have important implications for understanding rDNA biology within the context of cell physiology and whole-organism phenotypes.
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17
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Tulpová Z, Kovařík A, Toegelová H, Navrátilová P, Kapustová V, Hřibová E, Vrána J, Macas J, Doležel J, Šimková H. Fine structure and transcription dynamics of bread wheat ribosomal DNA loci deciphered by a multi-omics approach. Plant Genome 2022; 15:e20191. [PMID: 35092350 DOI: 10.1002/tpg2.20191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
Three out of four RNA components of ribosomes are encoded by 45S ribosomal DNA (rDNA) loci, which are organized as long head-to-tail tandem arrays of nearly identical units, spanning several megabases of sequence. Due to this structure, the rDNA loci are the major sources of gaps in genome assemblies, and gene copy number, sequence composition, and expression status of particular arrays remain elusive, especially in complex genomes harboring multiple loci. Here we conducted a multi-omics study to decipher the 45S rDNA loci in hexaploid bread wheat. Coupling chromosomal genomics with optical mapping, we reconstructed individual rDNA arrays, enabling locus-specific analyses of transcription activity and methylation status from RNA- and bisulfite-sequencing data. We estimated a total of 6,650 rDNA units in the bread wheat genome, with approximately 2,321, 3,910, 253, and 50 gene copies located in short arms of chromosomes 1B, 6B, 5D, and 1A, respectively. Only 1B and 6B loci contributed substantially to rRNA transcription at a roughly 2:1 ratio. The ratio varied among five tissues analyzed (embryo, coleoptile, root tip, primary leaf, mature leaf), being the highest (2.64:1) in mature leaf and lowest (1.72:1) in coleoptile. Cytosine methylation was considerably higher in CHG context in the silenced 5D locus as compared with the active 1B and 6B loci. In conclusion, a fine genomic organization and tissue-specific expression of rDNA loci were deciphered, for the first time, in a complex polyploid species. The results are discussed in the context of wheat evolution and transcription regulation.
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Affiliation(s)
- Zuzana Tulpová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Aleš Kovařík
- Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic
| | - Helena Toegelová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Pavla Navrátilová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Veronika Kapustová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Eva Hřibová
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Jan Vrána
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Jiří Macas
- Biology Centre, Institute of Plant Molecular Biology, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Jaroslav Doležel
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
| | - Hana Šimková
- Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic
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18
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Rosselló JA, Maravilla AJ, Rosato M. The Nuclear 35S rDNA World in Plant Systematics and Evolution: A Primer of Cautions and Common Misconceptions in Cytogenetic Studies. Front Plant Sci 2022; 13:788911. [PMID: 35283933 PMCID: PMC8908318 DOI: 10.3389/fpls.2022.788911] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 01/27/2022] [Indexed: 05/04/2023]
Abstract
The ubiquitous presence of rRNA genes in nuclear, plastid, and mitochondrial genomes has provided an opportunity to use genomic markers to infer patterns of molecular and organismic evolution as well as to assess systematic issues throughout the tree of life. The number, size, location, and activity of the 35S rDNA cistrons in plant karyotypes have been used as conventional cytogenetic landmarks. Their scrutiny has been useful to infer patterns of chromosomal evolution and the data have been used as a proxy for assessing species discrimination, population differentiation and evolutionary relationships. The correct interpretation of rDNA markers in plant taxonomy and evolution is not free of drawbacks given the complexities derived from the lability of the genetic architecture, the diverse patterns of molecular change, and the fate and evolutionary dynamics of the rDNA units in hybrids and polyploid species. In addition, the terminology used by independent authors is somewhat vague, which often complicates comparisons. To date, no efforts have been reported addressing the potential problems and limitations involved in generating, utilizing, and interpreting the data from the 35S rDNA in cytogenetics. This review discusses the main technical and conceptual limitations of these rDNA markers obtained by cytological and karyological experimental work, in order to clarify biological and evolutionary inferences postulated in a systematic and phylogenetic context. Also, we provide clarification for some ambiguity and misconceptions in terminology usually found in published work that may help to improve the usage of the 35S ribosomal world in plant evolution.
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19
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Cockrell AJ, Gerton JL. Nucleolar Organizer Regions as Transcription-Based Scaffolds of Nucleolar Structure and Function. Results Probl Cell Differ 2022; 70:551-580. [PMID: 36348121 DOI: 10.1007/978-3-031-06573-6_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Eukaryotic genomes maintain multiple copies of ribosomal DNA gene repeats in tandem arrays to provide sufficient ribosomal RNAs to make ribosomes. These DNA repeats are the most highly transcribed regions of the genome, with dedicated transcriptional machinery to manage the enormous task of producing more than 50% of the total RNA in a proliferating cell. The arrays are called nucleolar organizer regions (NORs) and constitute the scaffold of the nucleolar compartment, where ribosome biogenesis occurs. Advances in molecular and cellular biology have brought great insights into how these arrays are transcribed and organized within genomes. Much of their biology is driven by their high transcription level, which has also driven the development of unique methods to understand rDNA gene activity, beginning with classic techniques such as silver staining and Miller spreads. However, the application of modern methodologies such as CRISPR gene editing, super-resolution microscopy, and long-read sequencing has enabled recent advances described herein, with many more discoveries possible soon. This chapter highlights what is known about NOR transcription and organization and the techniques applied historically and currently. Given the potential for NORs to impact organismal health and disease, as highlighted at the end of the chapter, the field must continue to develop and apply innovative analysis to understand genetic, epigenetic, and organizer properties of the ribosomal DNA repeats.
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Affiliation(s)
- Alexandria J Cockrell
- Stowers Institute for Medical Research, Kansas City, MO, USA
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Jennifer L Gerton
- Stowers Institute for Medical Research, Kansas City, MO, USA.
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA.
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20
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Abstract
Although commonly regarded as nearly identical in sequence, 45S ribosomal RNA genes represent a massive source of genetic variation at different levels. Unfortunately, due to their repetitive nature and the difficulty to assemble their multiple copies in tandem, these important genomic elements remain largely unexplored in sequencing projects. Here, I describe how to exploit next generation sequencing data to estimate their copy number in an organism and detect true polymorphic sites within and among individuals. Furthermore, for species that carry multiple 45S ribosomal RNA gene clusters, I show how to make use of experimental populations to assign some of these variants to their cluster of origin.
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Affiliation(s)
- Fernando A Rabanal
- Department of Molecular Biology, Max Planck Institute for Biology, Tübingen, Germany.
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21
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Hemleben V, Grierson D, Borisjuk N, Volkov RA, Kovarik A. Personal Perspectives on Plant Ribosomal RNA Genes Research: From Precursor-rRNA to Molecular Evolution. Front Plant Sci 2021; 12:797348. [PMID: 34992624 PMCID: PMC8724763 DOI: 10.3389/fpls.2021.797348] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/26/2021] [Indexed: 06/13/2023]
Abstract
The history of rDNA research started almost 90 years ago when the geneticist, Barbara McClintock observed that in interphase nuclei of maize the nucleolus was formed in association with a specific region normally located near the end of a chromosome, which she called the nucleolar organizer region (NOR). Cytologists in the twentieth century recognized the nucleolus as a common structure in all eukaryotic cells, using both light and electron microscopy and biochemical and genetic studies identified ribosomes as the subcellular sites of protein synthesis. In the mid- to late 1960s, the synthesis of nuclear-encoded rRNA was the only system in multicellular organisms where transcripts of known function could be isolated, and their synthesis and processing could be studied. Cytogenetic observations of NOR regions with altered structure in plant interspecific hybrids and detailed knowledge of structure and function of rDNA were prerequisites for studies of nucleolar dominance, epistatic interactions of rDNA loci, and epigenetic silencing. In this article, we focus on the early rDNA research in plants, performed mainly at the dawn of molecular biology in the 60 to 80-ties of the last century which presented a prequel to the modern genomic era. We discuss - from a personal view - the topics such as synthesis of rRNA precursor (35S pre-rRNA in plants), processing, and the organization of 35S and 5S rDNA. Cloning and sequencing led to the observation that the transcribed and processed regions of the rRNA genes vary enormously, even between populations and species, in comparison with the more conserved regions coding for the mature rRNAs. Epigenetic phenomena and the impact of hybridization and allopolyploidy on rDNA expression and homogenization are discussed. This historical view of scientific progress and achievements sets the scene for the other articles highlighting the immense progress in rDNA research published in this special issue of Frontiers in Plant Science on "Molecular organization, evolution, and function of ribosomal DNA."
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Affiliation(s)
- Vera Hemleben
- Center of Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Donald Grierson
- Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Nikolai Borisjuk
- School of Life Sciences, Huaiyin Normal University, Huai'an, China
| | - Roman A. Volkov
- Department of Molecular Genetics and Biotechnology, Yuriy Fedkovych Chernivtsi National University, Chernivtsi, Ukraine
| | - Ales Kovarik
- Laboratory of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
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22
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Abstract
Chromosomes are the carriers of inheritable traits and define cell function and development. This is not only based on the linear DNA sequence of chromosomes but also on the additional molecular information they are associated with, including the transcription machinery, histone modifications, and their three-dimensional folding. The synergistic application of experimental approaches and computer simulations has helped to unveil how these organizational layers of the genome interplay in various organisms. However, such multidisciplinary approaches are still rarely explored in the plant kingdom. Here, we provide an overview of our current knowledge on plant 3D genome organization and review recent efforts to integrate cutting-edge experiments from microscopy and next-generation sequencing approaches with theoretical models. Building on these recent approaches, we propose possible avenues to extend the application of theoretical modeling in the characterization of the 3D genome organization in plants.
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Affiliation(s)
- Marco Di Stefano
- Institute of Human Genetics, Centre National de la Recherche Scientifique, University of Montpellier, Montpellier, France
| | - Hans-Wilhelm Nützmann
- The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK
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23
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Luo Y, Shi DQ, Jia PF, Bao Y, Li HJ, Yang WC. Nucleolar histone deacetylases HDT1, HDT2 and HDT3 regulate plant reproductive development. J Genet Genomics 2021; 49:30-39. [PMID: 34699991 DOI: 10.1016/j.jgg.2021.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 12/15/2022]
Abstract
Nucleolus is a membrane-less organelle where ribosomes are assembled and rRNAs transcribed and processed. The assembled ribosomes composed of ribosomal proteins and rRNAs synthesize proteins for cell survival. In plants, the loss of nucleolar ribosomal proteins often causes gametophytically or embryonically lethality. The amount of rRNAs are under stringent regulation according to demand and partially switched off by epigenetic modifications. However, the molecular mechanism for the selective activation or silencing is still unclear, and the transcriptional coordination of rRNAs and ribosomal proteins is also unknown. Here we report the critical role of three Arabidopsis nucleolar protein HDT1, HDT2 and HDT3 in fertility and transcription of rDNAs and rRNA processing-related genes through histone acetylation. This study highlights the important roles of transcriptional repression of ribosome biogenesis-related genes for plant reproductive development.
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Affiliation(s)
- Yu Luo
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dong-Qiao Shi
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng-Fei Jia
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuan Bao
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hong-Ju Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei-Cai Yang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
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24
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Chaux-Jukic F, O'Donnell S, Craig RJ, Eberhard S, Vallon O, Xu Z. Architecture and evolution of subtelomeres in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2021; 49:7571-7587. [PMID: 34165564 PMCID: PMC8287924 DOI: 10.1093/nar/gkab534] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/01/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
In most eukaryotes, subtelomeres are dynamic genomic regions populated by multi-copy sequences of different origins, which can promote segmental duplications and chromosomal rearrangements. However, their repetitive nature has complicated the efforts to sequence them, analyse their structure and infer how they evolved. Here, we use recent genome assemblies of Chlamydomonas reinhardtii based on long-read sequencing to comprehensively describe the subtelomere architecture of the 17 chromosomes of this model unicellular green alga. We identify three main repeated elements present at subtelomeres, which we call Sultan, Subtile and Suber, alongside three chromosome extremities with ribosomal DNA as the only identified component of their subtelomeres. The most common architecture, present in 27 out of 34 subtelomeres, is a heterochromatic array of Sultan elements adjacent to the telomere, followed by a transcribed Spacer sequence, a G-rich microsatellite and transposable elements. Sequence similarity analyses suggest that Sultan elements underwent segmental duplications within each subtelomere and rearranged between subtelomeres at a much lower frequency. Analysis of other green algae reveals species-specific repeated elements that are shared across subtelomeres, with an overall organization similar to C. reinhardtii. This work uncovers the complexity and evolution of subtelomere architecture in green algae.
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Affiliation(s)
- Frédéric Chaux-Jukic
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Samuel O'Donnell
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3FL, Edinburgh, UK
| | - Stephan Eberhard
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Olivier Vallon
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Zhou Xu
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
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25
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Franek M, Kilar A, Fojtík P, Olšinová M, Benda A, Rotrekl V, Dvořáčková M, Fajkus J. Super-resolution microscopy of chromatin fibers and quantitative DNA methylation analysis of DNA fiber preparations. J Cell Sci 2021; 134:jcs258374. [PMID: 34350964 DOI: 10.1242/jcs.258374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 07/05/2021] [Indexed: 11/20/2022] Open
Abstract
Analysis of histone variants and epigenetic marks is dominated by genome-wide approaches in the form of chromatin immunoprecipitation-sequencing (ChIP-seq) and related methods. Although uncontested in their value for single-copy genes, mapping the chromatin of DNA repeats is problematic for biochemical techniques that involve averaging of cell populations or analysis of clusters of tandem repeats in a single-cell analysis. Extending chromatin and DNA fibers allows us to study the epigenetics of individual repeats in their specific chromosomal context, and thus constitutes an important tool for gaining a complete understanding of the epigenetic organization of genomes. We report that using an optimized fiber extension protocol is essential in order to obtain more reproducible data and to minimize the clustering of fibers. We also demonstrate that the use of super-resolution microscopy is important for reliable evaluation of the distribution of histone modifications on individual fibers. Furthermore, we introduce a custom script for the analysis of methylation levels on DNA fibers and apply it to map the methylation of telomeres, ribosomal genes and centromeres.
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Affiliation(s)
- Michal Franek
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
| | - Agata Kilar
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, CZ-61137 Brno, Czech Republic
| | - Petr Fojtík
- International Clinical Research Center (ICRC) at St. Anne's University Hospital, Pekařská 53, CZ-65691 Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
| | - Marie Olšinová
- Charles University, Faculty of Science, Biology Section, Imaging methods core facility at BIOCEV, Průmyslová 595, 252 50 Vestec, Czech Republic
| | - Aleš Benda
- Charles University, Faculty of Science, Biology Section, Imaging methods core facility at BIOCEV, Průmyslová 595, 252 50 Vestec, Czech Republic
| | - Vladimír Rotrekl
- International Clinical Research Center (ICRC) at St. Anne's University Hospital, Pekařská 53, CZ-65691 Brno, Czech Republic
- Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
| | - Jíří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, CZ-62500 Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, CZ-61137 Brno, Czech Republic
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26
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Chaux-Jukic F, O'Donnell S, Craig RJ, Eberhard S, Vallon O, Xu Z. Architecture and evolution of subtelomeres in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2021. [PMID: 34165564 DOI: 10.1101/2021.01.29.428817)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
In most eukaryotes, subtelomeres are dynamic genomic regions populated by multi-copy sequences of different origins, which can promote segmental duplications and chromosomal rearrangements. However, their repetitive nature has complicated the efforts to sequence them, analyse their structure and infer how they evolved. Here, we use recent genome assemblies of Chlamydomonas reinhardtii based on long-read sequencing to comprehensively describe the subtelomere architecture of the 17 chromosomes of this model unicellular green alga. We identify three main repeated elements present at subtelomeres, which we call Sultan, Subtile and Suber, alongside three chromosome extremities with ribosomal DNA as the only identified component of their subtelomeres. The most common architecture, present in 27 out of 34 subtelomeres, is a heterochromatic array of Sultan elements adjacent to the telomere, followed by a transcribed Spacer sequence, a G-rich microsatellite and transposable elements. Sequence similarity analyses suggest that Sultan elements underwent segmental duplications within each subtelomere and rearranged between subtelomeres at a much lower frequency. Analysis of other green algae reveals species-specific repeated elements that are shared across subtelomeres, with an overall organization similar to C. reinhardtii. This work uncovers the complexity and evolution of subtelomere architecture in green algae.
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Affiliation(s)
- Frédéric Chaux-Jukic
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Samuel O'Donnell
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, EH9 3FL, Edinburgh, UK
| | - Stephan Eberhard
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Olivier Vallon
- Sorbonne Université, CNRS, UMR7141, Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light-Sensing in Microalgae, 75005 Paris, France
| | - Zhou Xu
- Sorbonne Université, CNRS, UMR7238, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, 75005 Paris, France
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27
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Lopez FB, Fort A, Tadini L, Probst AV, McHale M, Friel J, Ryder P, Pontvianne F, Pesaresi P, Sulpice R, McKeown P, Brychkova G, Spillane C. Gene dosage compensation of rRNA transcript levels in Arabidopsis thaliana lines with reduced ribosomal gene copy number. Plant Cell 2021; 33:1135-1150. [PMID: 33793816 PMCID: PMC8225240 DOI: 10.1093/plcell/koab020] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 12/24/2020] [Indexed: 05/08/2023]
Abstract
The 45S rRNA genes (rDNA) are among the largest repetitive elements in eukaryotic genomes. rDNA consists of tandem arrays of rRNA genes, many of which are transcriptionally silenced. Silent rDNA repeats may act as 'back-up' copies for ribosome biogenesis and have nuclear organization roles. Through Cas9-mediated genome editing in the Arabidopsis thaliana female gametophyte, we reduced 45S rDNA copy number (CN) to a plateau of ∼10%. Two independent lines had rDNA CNs reduced by up to 90% at the T7 generation, named low copy number (LCN) lines. Despite drastic reduction of rDNA copies, rRNA transcriptional rates, and steady-state levels remained the same as wild-type plants. Gene dosage compensation of rRNA transcript levels was associated with reduction of silencing histone marks at rDNA loci and altered Nucleolar Organiser Region 2 organization. Although overall genome integrity of LCN lines appears unaffected, a chromosome segmental duplication occurred in one of the lines. Transcriptome analysis of LCN seedlings identified several shared dysregulated genes and pathways in both independent lines. Cas9 genome editing of rRNA repeats to generate LCN lines provides a powerful technique to elucidate rDNA dosage compensation mechanisms and impacts of low rDNA CN on genome stability, development, and cellular processes.
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Affiliation(s)
- Francesca B Lopez
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Antoine Fort
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
- Systems Biology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Luca Tadini
- Dipartimento di Bioscienze, Universit� degli Studi di Milano, 20133 Milano, Italy
| | - Aline V Probst
- CNRS, GReD, Universit� Clermont Auvergne, INSERM, 63001 Clermont–Ferrand, France
| | - Marcus McHale
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
- Systems Biology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - James Friel
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Peter Ryder
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Fr�d�ric Pontvianne
- CNRS, Laboratoire G�nome et D�veloppement des Plantes (LGDP), Universit� de Perpignan Via Domitia, Perpignan, France
| | - Paolo Pesaresi
- Dipartimento di Bioscienze, Universit� degli Studi di Milano, 20133 Milano, Italy
| | - Ronan Sulpice
- Systems Biology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Peter McKeown
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Galina Brychkova
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
| | - Charles Spillane
- Genetics and Biotechnology Laboratory, Plant & AgriBiosciences Research Centre (PABC), Ryan Institute, National University of Ireland Galway, Galway H91 REW4, Ireland
- Author for correspondence:
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28
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Benoit M. The right dose: molecular compensation maintains rRNA homeostasis upon reduction of ribosomal gene dosage in Arabidopsis. Plant Cell 2021; 33:1089-1090. [PMID: 35234967 PMCID: PMC8889994 DOI: 10.1093/plcell/koab019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 06/14/2023]
Affiliation(s)
- Matthias Benoit
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA
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29
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McKinlay A, Fultz D, Wang F, Pikaard CS. Targeted Enrichment of rRNA Gene Tandem Arrays for Ultra-Long Sequencing by Selective Restriction Endonuclease Digestion. Front Plant Sci 2021; 12:656049. [PMID: 33995452 PMCID: PMC8113872 DOI: 10.3389/fpls.2021.656049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/06/2021] [Indexed: 05/26/2023]
Abstract
Large regions of nearly identical repeats, such as the 45S ribosomal RNA (rRNA) genes of Nucleolus Organizer Regions (NORs), can account for major gaps in sequenced genomes. To assemble these regions, ultra-long sequencing reads that span multiple repeats have the potential to reveal sets of repeats that collectively have sufficient sequence variation to unambiguously define that interval and recognize overlapping reads. Because individual repetitive loci typically represent a small proportion of the genome, methods to enrich for the regions of interest are desirable. Here we describe a simple method that achieves greater than tenfold enrichment of Arabidopsis thaliana 45S rRNA gene sequences among ultra-long Oxford Nanopore Technology sequencing reads. This method employs agarose-embedded genomic DNA that is subjected to restriction endonucleases digestion using a cocktail of enzymes predicted to be non-cutters of rRNA genes. Most of the genome is digested into small fragments that diffuse out of the agar plugs, whereas rRNA gene arrays are retained. In principle, the approach can also be adapted for sequencing other repetitive loci for which gaps exist in a reference genome.
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Affiliation(s)
- Anastasia McKinlay
- Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, United States
| | - Dalen Fultz
- Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, United States
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, United States
| | - Feng Wang
- Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, United States
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, United States
| | - Craig S. Pikaard
- Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, United States
- Howard Hughes Medical Institute, Indiana University, Bloomington, IN, United States
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30
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Kutashev KO, Franek M, Diamanti K, Komorowski J, Olšinová M, Dvořáčková M. Nucleolar rDNA folds into condensed foci with a specific combination of epigenetic marks. Plant J 2021; 105:1534-1548. [PMID: 33314374 DOI: 10.1111/tpj.15130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 11/30/2020] [Indexed: 05/15/2023]
Abstract
Arabidopsis thaliana 45S ribosomal genes (rDNA) are located in tandem arrays called nucleolus organizing regions on the termini of chromosomes 2 and 4 (NOR2 and NOR4) and encode rRNA, a crucial structural element of the ribosome. The current model of rDNA organization suggests that inactive rRNA genes accumulate in the condensed chromocenters in the nucleus and at the nucleolar periphery, while the nucleolus delineates active genes. We challenge the perspective that all intranucleolar rDNA is active by showing that a subset of nucleolar rDNA assembles into condensed foci marked by H3.1 and H3.3 histones that also contain the repressive H3K9me2 histone mark. By using plant lines containing a low number of rDNA copies, we further found that the condensed foci relate to the folding of rDNA, which appears to be a common mechanism of rDNA regulation inside the nucleolus. The H3K9me2 histone mark found in condensed foci represents a typical modification of bulk inactive rDNA, as we show by genome-wide approaches, similar to the H2A.W histone variant. The euchromatin histone marks H3K27me3 and H3K4me3, in contrast, do not colocalize with nucleolar foci and their overall levels in the nucleolus are very low. We further demonstrate that the rDNA promoter is an important regulatory region of the rDNA, where the distribution of histone variants and histone modifications are modulated in response to rDNA activity.
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Affiliation(s)
- Konstantin O Kutashev
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, Brno, 61137, Czech Republic
| | - Michal Franek
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic
| | - Klev Diamanti
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, 751 24, Sweden
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, 751 08, Sweden
| | - Jan Komorowski
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, 751 24, Sweden
- Institute of Computer Science, Polish Academy of Sciences, Warsaw, 012-48, Poland
| | - Marie Olšinová
- BioCEV Imaging Methods Core Facility, Průmyslová 595, Vestec, 252 50, Czech Republic
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno, 62500, Czech Republic
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31
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Goffová I, Fajkus J. The rDNA Loci-Intersections of Replication, Transcription, and Repair Pathways. Int J Mol Sci 2021; 22:1302. [PMID: 33525595 PMCID: PMC7865372 DOI: 10.3390/ijms22031302] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 01/25/2021] [Accepted: 01/25/2021] [Indexed: 12/28/2022] Open
Abstract
Genes encoding ribosomal RNA (rDNA) are essential for cell survival and are particularly sensitive to factors leading to genomic instability. Their repetitive character makes them prone to inappropriate recombinational events arising from collision of transcriptional and replication machineries, resulting in unstable rDNA copy numbers. In this review, we summarize current knowledge on the structure and organization of rDNA, its role in sensing changes in the genome, and its linkage to aging. We also review recent findings on the main factors involved in chromatin assembly and DNA repair in the maintenance of rDNA stability in the model plants Arabidopsis thaliana and the moss Physcomitrella patens, providing a view across the plant evolutionary tree.
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Affiliation(s)
- Ivana Goffová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, CZ-61137 Brno, Czech Republic;
- Chromatin Molecular Complexes, Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Jiří Fajkus
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, CZ-61137 Brno, Czech Republic;
- Chromatin Molecular Complexes, Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, CZ-61265 Brno, Czech Republic
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32
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Sims J, Sestini G, Elgert C, von Haeseler A, Schlögelhofer P. Sequencing of the Arabidopsis NOR2 reveals its distinct organization and tissue-specific rRNA ribosomal variants. Nat Commun 2021; 12:387. [PMID: 33452254 DOI: 10.1038/s41467-020-20728-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 12/15/2020] [Indexed: 11/20/2022] Open
Abstract
Despite vast differences between organisms, some characteristics of their genomes are conserved, such as the nucleolus organizing region (NOR). The NOR is constituted of multiple, highly repetitive rDNA genes, encoding the catalytic ribosomal core RNAs which are transcribed from 45S rDNA units. Their precise sequence information and organization remain uncharacterized. Here, using a combination of long- and short-read sequencing technologies we assemble contigs of the Arabidopsis NOR2 rDNA domain. We identify several expressed rRNA gene variants which are integrated into translating ribosomes in a tissue-specific manner. These findings support the concept of tissue specific ribosome subpopulations that differ in their rRNA composition and provide insights into the higher order organization of NOR2. The nucleolus organizing region (NOR) consists of multiple, highly repetitive rDNA genes. Here Sims et al. use both long- and short-read sequencing to determine the organization and sequence of Arabidopsis NOR2 rDNA and show that different rRNA gene variants are integrated into translating ribosomes in a tissue-specific manner.
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33
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Sims J, Rabanal FA, Elgert C, von Haeseler A, Schlögelhofer P. It Is Just a Matter of Time: Balancing Homologous Recombination and Non-homologous End Joining at the rDNA Locus During Meiosis. Front Plant Sci 2021; 12:773052. [PMID: 34777453 PMCID: PMC8580885 DOI: 10.3389/fpls.2021.773052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/04/2021] [Indexed: 05/17/2023]
Abstract
Ribosomal RNA genes (rDNAs) are located in large domains of hundreds of rDNA units organized in a head-to-tail manner. The proper and stable inheritance of rDNA clusters is of paramount importance for survival. Yet, these highly repetitive elements pose a potential risk to the genome since they can undergo non-allelic exchanges. Here, we review the current knowledge of the organization of the rDNA clusters in Arabidopsis thaliana and their stability during meiosis. Recent findings suggest that during meiosis, all rDNA loci are embedded within the nucleolus favoring non-homologous end joining (NHEJ) as a repair mechanism, while DNA repair via homologous recombination (HR) appears to be a rare event. We propose a model where (1) frequent meiotic NHEJ events generate abundant single nucleotide polymorphisms and insertions/deletions within the rDNA, resulting in a heterogeneous population of rDNA units and (2) rare HR events dynamically change rDNA unit numbers, only to be observed in large populations over many generations. Based on the latest efforts to delineate the entire rDNA sequence in A. thaliana, we discuss evidence supporting this model. The results compiled so far draw a surprising picture of rDNA sequence heterogeneity between individual units. Furthermore, rDNA cluster sizes have been recognized as relatively stable when observing less than 10 generations, yet emerged as major determinant of genome size variation between different A. thaliana ecotypes. The sequencing efforts also revealed that transcripts from the diverse rDNA units yield heterogenous ribosome populations with potential functional implications. These findings strongly motivate further research to understand the mechanisms that maintain the metastable state of rDNA loci.
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Affiliation(s)
- Jason Sims
- Department of Chromosome Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Vienna, Austria
- *Correspondence: Jason Sims,
| | - Fernando A. Rabanal
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Christiane Elgert
- Center for Integrative Bioinformatics Vienna (CIBIV), Max Perutz Labs, University of Vienna and Medical University of Vienna, Vienna BioCenter, Vienna, Austria
| | - Arndt von Haeseler
- Center for Integrative Bioinformatics Vienna (CIBIV), Max Perutz Labs, University of Vienna and Medical University of Vienna, Vienna BioCenter, Vienna, Austria
- Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria
| | - Peter Schlögelhofer
- Department of Chromosome Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Vienna, Austria
- Peter Schlögelhofer,
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34
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Borowska-Zuchowska N, Robaszkiewicz E, Mykhailyk S, Wartini J, Pinski A, Kovarik A, Hasterok R. To Be or Not to Be Expressed: The First Evidence of a Nucleolar Dominance Tissue-Specificity in Brachypodium hybridum. Front Plant Sci 2021; 12:768347. [PMID: 34938308 PMCID: PMC8685274 DOI: 10.3389/fpls.2021.768347] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/09/2021] [Indexed: 05/20/2023]
Abstract
Nucleolar dominance (ND) is an epigenetic, developmentally regulated phenomenon that describes the selective inactivation of 35S rDNA loci derived from one progenitor of a hybrid or allopolyploid. The presence of ND was documented in an allotetraploid grass, Brachypodium hybridum (genome composition DDSS), which is a polyphyletic species that arose from crosses between two putative ancestors that resembled the modern B. distachyon (DD) and B. stacei (SS). In this work, we investigated the developmental stability of ND in B. hybridum genotype 3-7-2 and compared it with the reference genotype ABR113. We addressed the question of whether the ND is established in generative tissues such as pollen mother cells (PMC). We examined condensation of rDNA chromatin by fluorescence in situ hybridization employing state-of-art confocal microscopy. The transcription of rDNA homeologs was determined by reverse-transcription cleaved amplified polymorphic sequence analysis. In ABR113, the ND was stable in all tissues analyzed (primary and adventitious root, leaf, and spikes). In contrast, the 3-7-2 individuals showed a strong upregulation of the S-genome units in adventitious roots but not in other tissues. Microscopic analysis of the 3-7-2 PMCs revealed extensive decondensation of the D-genome loci and their association with the nucleolus in meiosis. As opposed, the S-genome loci were always highly condensed and localized outside the nucleolus. These results indicate that genotype-specific loss of ND in B. hybridum occurs probably after fertilization during developmental processes. This finding supports our view that B. hybridum is an attractive model to study ND in grasses.
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Affiliation(s)
- Natalia Borowska-Zuchowska
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
- *Correspondence: Natalia Borowska-Zuchowska,
| | - Ewa Robaszkiewicz
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Serhii Mykhailyk
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Joanna Wartini
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Artur Pinski
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Ales Kovarik
- Department of Molecular Epigenetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czechia
| | - Robert Hasterok
- Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
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35
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Havlová K, Fajkus J. G4 Structures in Control of Replication and Transcription of rRNA Genes. Front Plant Sci 2020; 11:593692. [PMID: 33133121 PMCID: PMC7579416 DOI: 10.3389/fpls.2020.593692] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
Genes encoding 45S ribosomal RNA (rDNA) are known for their abundance within eukaryotic genomes and for their unstable copy numbers in response to changes in various genetic and epigenetic factors. Commonly, we understand as epigenetic factors (affecting gene expression without a change in DNA sequence), namely DNA methylation, histone posttranslational modifications, histone variants, RNA interference, nucleosome remodeling and assembly, and chromosome position effect. All these were actually shown to affect activity and stability of rDNA. Here, we focus on another phenomenon - the potential of DNA containing shortly spaced oligo-guanine tracts to form quadruplex structures (G4). Interestingly, sites with a high propensity to form G4 were described in yeast, animal, and plant rDNAs, in addition to G4 at telomeres, some gene promoters, and transposons, suggesting the evolutionary ancient origin of G4 as a regulatory module. Here, we present examples of rDNA promoter regions with extremely high potential to form G4 in two model plants, Arabidopsis thaliana and Physcomitrella patens. The high G4 potential is balanced by the activity of G4-resolving enzymes. The ability of rDNA to undergo these "structural gymnastics" thus represents another layer of the rich repertoire of epigenetic regulations, which is pronounced in rDNA due to its highly repetitive character.
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Affiliation(s)
- Kateřina Havlová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
- Chromatin Molecular Complexes, Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Jiří Fajkus
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
- Chromatin Molecular Complexes, Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Brno, Czechia
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
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36
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Picart-Picolo A, Grob S, Picault N, Franek M, Llauro C, Halter T, Maier TR, Jobet E, Descombin J, Zhang P, Paramasivan V, Baum TJ, Navarro L, Dvořáčková M, Mirouze M, Pontvianne F. Large tandem duplications affect gene expression, 3D organization, and plant-pathogen response. Genome Res 2020; 30:1583-1592. [PMID: 33033057 PMCID: PMC7605254 DOI: 10.1101/gr.261586.120] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 09/15/2020] [Indexed: 02/07/2023]
Abstract
Rapid plant genome evolution is crucial to adapt to environmental changes. Chromosomal rearrangements and gene copy number variation (CNV) are two important tools for genome evolution and sources for the creation of new genes. However, their emergence takes many generations. In this study, we show that in Arabidopsis thaliana, a significant loss of ribosomal RNA (rRNA) genes with a past history of a mutation for the chromatin assembly factor 1 (CAF1) complex causes rapid changes in the genome structure. Using long-read sequencing and microscopic approaches, we have identified up to 15 independent large tandem duplications in direct orientation (TDDOs) ranging from 60 kb to 1.44 Mb. Our data suggest that these TDDOs appeared within a few generations, leading to the duplication of hundreds of genes. By subsequently focusing on a line only containing 20% of rRNA gene copies (20rDNA line), we investigated the impact of TDDOs on 3D genome organization, gene expression, and cytosine methylation. We found that duplicated genes often accumulate more transcripts. Among them, several are involved in plant–pathogen response, which could explain why the 20rDNA line is hyper-resistant to both bacterial and nematode infections. Finally, we show that the TDDOs create gene fusions and/or truncations and discuss their potential implications for the evolution of plant genomes.
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Affiliation(s)
- Ariadna Picart-Picolo
- CNRS, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France
| | - Stefan Grob
- Institute of Plant and Microbial Biology, University of Zurich, CH-8008 Zurich, Switzerland
| | - Nathalie Picault
- CNRS, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France
| | - Michal Franek
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, 625 00 Brno, Czech Republic
| | - Christel Llauro
- CNRS, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France
| | - Thierry Halter
- ENS, IBENS, CNRS/INSERM, PSL Research University, 75005 Paris, France
| | - Tom R Maier
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa 50011, USA
| | - Edouard Jobet
- CNRS, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France
| | - Julie Descombin
- CNRS, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France
| | - Panpan Zhang
- UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,IRD, UMR232 DIADE, 34394 Montpellier, France
| | | | - Thomas J Baum
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa 50011, USA
| | - Lionel Navarro
- ENS, IBENS, CNRS/INSERM, PSL Research University, 75005 Paris, France
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, 625 00 Brno, Czech Republic
| | - Marie Mirouze
- UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,IRD, UMR232 DIADE, 34394 Montpellier, France
| | - Frédéric Pontvianne
- CNRS, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France.,UPVD, LGDP UMR5096, Université de Perpignan, 66860 Perpignan, France
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37
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Iwakawa H, Takahashi H, Machida Y, Machida C. Roles of ASYMMETRIC LEAVES2 (AS2) and Nucleolar Proteins in the Adaxial-Abaxial Polarity Specification at the Perinucleolar Region in Arabidopsis. Int J Mol Sci 2020; 21:E7314. [PMID: 33022996 PMCID: PMC7582388 DOI: 10.3390/ijms21197314] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/27/2020] [Accepted: 09/29/2020] [Indexed: 12/14/2022] Open
Abstract
Leaves of Arabidopsis develop from a shoot apical meristem grow along three (proximal-distal, adaxial-abaxial, and medial-lateral) axes and form a flat symmetric architecture. ASYMMETRIC LEAVES2 (AS2), a key regulator for leaf adaxial-abaxial partitioning, encodes a plant-specific nuclear protein and directly represses the abaxial-determining gene ETTIN/AUXIN RESPONSE FACTOR3 (ETT/ARF3). How AS2 could act as a critical regulator, however, has yet to be demonstrated, although it might play an epigenetic role. Here, we summarize the current understandings of the genetic, molecular, and cellular functions of AS2. A characteristic genetic feature of AS2 is the presence of a number of (about 60) modifier genes, mutations of which enhance the leaf abnormalities of as2. Although genes for proteins that are involved in diverse cellular processes are known as modifiers, it has recently become clear that many modifier proteins, such as NUCLEOLIN1 (NUC1) and RNA HELICASE10 (RH10), are localized in the nucleolus. Some modifiers including ribosomal proteins are also members of the small subunit processome (SSUP). In addition, AS2 forms perinucleolar bodies partially colocalizing with chromocenters that include the condensed inactive 45S ribosomal RNA genes. AS2 participates in maintaining CpG methylation in specific exons of ETT/ARF3. NUC1 and RH10 genes are also involved in maintaining the CpG methylation levels and repressing ETT/ARF3 transcript levels. AS2 and nucleolus-localizing modifiers might cooperatively repress ETT/ARF3 to develop symmetric flat leaves. These results raise the possibility of a nucleolus-related epigenetic repression system operating for developmental genes unique to plants and predict that AS2 could be a molecule with novel functions that cannot be explained by the conventional concept of transcription factors.
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Affiliation(s)
- Hidekazu Iwakawa
- Graduate School of Bioscience and Biotechnology, Chubu University, 1200, Matsumoto-cho, Kasugai, Aichi 487-8501, Japan;
| | - Hiro Takahashi
- Graduate School of Medical Sciences, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan;
| | - Yasunori Machida
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Chiyoko Machida
- Graduate School of Bioscience and Biotechnology, Chubu University, 1200, Matsumoto-cho, Kasugai, Aichi 487-8501, Japan;
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38
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Santos AP, Gaudin V, Mozgová I, Pontvianne F, Schubert D, Tek AL, Dvořáčková M, Liu C, Fransz P, Rosa S, Farrona S. Tidying-up the plant nuclear space: domains, functions, and dynamics. J Exp Bot 2020; 71:5160-5178. [PMID: 32556244 PMCID: PMC8604271 DOI: 10.1093/jxb/eraa282] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 06/12/2020] [Indexed: 05/07/2023]
Abstract
Understanding how the packaging of chromatin in the nucleus is regulated and organized to guide complex cellular and developmental programmes, as well as responses to environmental cues is a major question in biology. Technological advances have allowed remarkable progress within this field over the last years. However, we still know very little about how the 3D genome organization within the cell nucleus contributes to the regulation of gene expression. The nuclear space is compartmentalized in several domains such as the nucleolus, chromocentres, telomeres, protein bodies, and the nuclear periphery without the presence of a membrane around these domains. The role of these domains and their possible impact on nuclear activities is currently under intense investigation. In this review, we discuss new data from research in plants that clarify functional links between the organization of different nuclear domains and plant genome function with an emphasis on the potential of this organization for gene regulation.
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Affiliation(s)
- Ana Paula Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova
de Lisboa, Oeiras, Portugal
| | - Valérie Gaudin
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, Versailles, France
| | - Iva Mozgová
- Biology Centre of the Czech Academy of Sciences, České
Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České
Budějovice, Czech Republic
| | - Frédéric Pontvianne
- CNRS, Laboratoire Génome et Développement des Plantes (LGDP), Université de
Perpignan Via Domitia, Perpignan, France
| | - Daniel Schubert
- Institute for Biology, Freie Universität Berlin, Berlin, Germany
| | - Ahmet L Tek
- Agricultural Genetic Engineering Department, Niğde Ömer Halisdemir
University, Niğde, Turkey
| | | | - Chang Liu
- Center for Plant Molecular Biology (ZMBP), University of
Tübingen, Tübingen, Germany
- Institute of Biology, University of Hohenheim, Stuttgart,
Germany
| | - Paul Fransz
- University of Amsterdam, Amsterdam, The
Netherlands
| | - Stefanie Rosa
- Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Sara Farrona
- Plant and AgriBiosciences Centre, Ryan Institute, NUI Galway,
Galway, Ireland
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39
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Abstract
In recent years, the study of plant three-dimensional nuclear architecture received increasing attention. Enabled by technological advances, our knowledge on nuclear architecture has greatly increased and we can now access large data sets describing its manifold aspects. The principles of nuclear organization in plants do not significantly differ from those in animals. Plant nuclear organization comprises various scales, ranging from gene loops to topologically associating domains to nuclear compartmentalization. However, whether plant three-dimensional chromosomal features also exert similar functions as in animals is less clear. This review discusses recent advances in the fields of three-dimensional chromosome folding and nuclear compartmentalization and describes a novel silencing mechanism, which is closely linked to nuclear architecture.
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Affiliation(s)
- Frédéric Pontvianne
- UPVD, LGDP, UMR5096, Université de Perpignan, Perpignan, France.
- CNRS, LGDP, UMR5096, Université de Perpignan, Perpignan, France.
| | - Stefan Grob
- Institute of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland.
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40
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Picart-Picolo A, Picart C, Picault N, Pontvianne F. Nucleolus-associated chromatin domains are maintained under heat stress, despite nucleolar reorganization in Arabidopsis thaliana. J Plant Res 2020; 133:463-470. [PMID: 32372397 DOI: 10.1007/s10265-020-01201-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 04/17/2020] [Indexed: 05/23/2023]
Abstract
Several layers of mechanisms participate in plant adaptation to heat-stress. For example, the plant metabolism switches from cell growth mode to stress adaptation mode. Ribosome biogenesis is one of the most energy costly pathways. That biogenesis process occurs in the nucleolus, the largest nuclear compartment, whose structure is highly dependent on this pathway. We used a nucleolar marker to track the structure of the nucleolus, and revealed a change in its sub-nucleolar distribution under heat stress. In addition, the nucleolus is implicated in other cellular processes, such as genome organization within the nucleus. However, our analyses of nucleolus-associated chromatin domains under heat stress did not reveal significant differences compared to the control plants, suggesting a lack of connection between two of the main functions of the nucleolus: ribosome biogenesis and nuclear organization.
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Affiliation(s)
- Ariadna Picart-Picolo
- CNRS, LGDP UMR5096, Université de Perpignan, Perpignan, France
- UPVD, LGDP UMR5096, Université de Perpignan, Perpignan, France
| | - Claire Picart
- CNRS, LGDP UMR5096, Université de Perpignan, Perpignan, France
- UPVD, LGDP UMR5096, Université de Perpignan, Perpignan, France
| | - Nathalie Picault
- CNRS, LGDP UMR5096, Université de Perpignan, Perpignan, France
- UPVD, LGDP UMR5096, Université de Perpignan, Perpignan, France
| | - Frederic Pontvianne
- CNRS, LGDP UMR5096, Université de Perpignan, Perpignan, France.
- UPVD, LGDP UMR5096, Université de Perpignan, Perpignan, France.
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Ibiapino A, García MÁ, Costea M, Stefanović S, Guerra M. Intense proliferation of rDNA sites and heterochromatic bands in two distantly related Cuscuta species (Convolvulaceae) with very large genomes and symmetric karyotypes. Genet Mol Biol 2020; 43:e20190068. [PMID: 32542306 PMCID: PMC7295182 DOI: 10.1590/1678-4685-gmb-2019-0068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/06/2020] [Indexed: 11/21/2022] Open
Abstract
The genome size varies widely among angiosperms but only a few clades present huge variation at a low phylogenetic level. Among diploid species of the genus Cuscuta the genome size increased enormously in at least two independent lineages: in species of subgenus Monogynella and in at least one species (C. indecora) of the subgenus Grammica. Curiously, the independent events lead to similar karyotypes, with 2n = 30 mostly metacentric chromosomes. In this paper we compared the patterns of heterochromatic bands and rDNA sites of C. indecora and C. monogyna, aiming to evaluate the role of these repetitive fractions in these karyotypes. We found out that the large genomes of these species were incremented by a huge number of small heterochromatic CMA+ and DAPI+ bands and 5S and 35 rDNA sites, most of them clearly colocalized with CMA+ bands. Silver nitrate impregnation revealed that the maximum number of nucleoli per nucleus was low in both species, suggesting that some of these sites may be inactive. Noteworthy, the tandem repeats did not generate large bands or sites but rather dozens of small blocks dispersed throughout the chromosomes, apparently contributing to conserve the original karyotype symmetry.
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Affiliation(s)
- Amália Ibiapino
- Universidade Federal de Pernambuco, Departamento de Botânica,
Recife, PE, Brazil
| | - Miguel Ángel García
- University of Toronto Mississauga, Department of Biology,
Mississauga, ON, Canada
- Royal Botanic Gardens Kew, Richmond, Surrey, United Kingdom
| | - Mihai Costea
- Wilfrid Laurier University, Department of Biology, Waterloo, ON,
Canada
| | - Saša Stefanović
- University of Toronto Mississauga, Department of Biology,
Mississauga, ON, Canada
| | - Marcelo Guerra
- Universidade Federal de Pernambuco, Departamento de Botânica,
Recife, PE, Brazil
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42
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van Sluis M, van Vuuren C, Mangan H, McStay B. NORs on human acrocentric chromosome p-arms are active by default and can associate with nucleoli independently of rDNA. Proc Natl Acad Sci U S A 2020; 117:10368-77. [PMID: 32332163 DOI: 10.1073/pnas.2001812117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
A detailed description of how the genome is organized within the human nucleus is a major research goal. Nucleolar organizer regions (NORs) comprising ribosomal DNA (rDNA) arrays are located on the p-arms of the five human acrocentric chromosomes. Here we characterize the rules of engagement between NORs and nucleoli. We reveal variation in rDNA distribution, with some primary cell lines containing as many as four acrocentrics devoid of rDNA. We establish the default status of NORs as active and show that acrocentric p-arms devoid of rDNA retain nucleolar association potential. Based on our data, we propose that in diploid human cells, all 10 acrocentric chromosomes are nucleolar-associated, with involvement of non-rDNA sequences buffering against variable rDNA distribution. Nucleoli, the sites of ribosome biogenesis and the largest structures in human nuclei, form around nucleolar organizer regions (NORs) comprising ribosomal DNA (rDNA) arrays. NORs are located on the p-arms of the five human acrocentric chromosomes. Defining the rules of engagement between these p-arms and nucleoli takes on added significance as describing the three-dimensional organization of the human genome represents a major research goal. Here we used fluorescent in situ hybridization (FISH) and immuno-FISH on metaphase chromosomes from karyotypically normal primary and hTERT-immortalized human cell lines to catalog NORs in terms of their relative rDNA content and activity status. We demonstrate that a proportion of acrocentric p-arms in cell lines and from normal human donors have no detectable rDNA. Surprisingly, we found that all NORs with detectable rDNA are active, as defined by upstream binding factor loading. We determined the nucleolar association status of all NORs during interphase, and found that nucleolar association of acrocentric p-arms can occur independently of rDNA content, suggesting that sequences elsewhere on these chromosome arms drive nucleolar association. In established cancer lines, we characterize a variety of chromosomal rearrangements involving acrocentric p-arms and observe silent, rDNA-containing NORs that are dissociated from nucleoli. In conclusion, our findings indicate that within human nuclei, positioning of all 10 acrocentric chromosomes is dictated by nucleolar association. Furthermore, these nucleolar associations are buffered against interindividual variation in the distribution of rDNA.
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Báez M, Souza G, Guerra M. Does the chromosomal position of 35S rDNA sites influence their transcription? A survey on Nothoscordum species (Amaryllidaceae). Genet Mol Biol 2020; 43:e20180194. [PMID: 31469154 PMCID: PMC7197985 DOI: 10.1590/1678-4685-gmb-2018-0194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 03/21/2019] [Indexed: 11/22/2022] Open
Abstract
35S ribosomal DNA (rDNA) sites are the regions where the ribosomal genes 18S, 5.8S and 25S, responsible for the formation of the nucleoli, are found. The fact that rDNA sites have non-random distribution on chromosomes suggests that their positions may influence their transcription. To identify if the preferentially transcribed rDNA sites occupy specific position, six species (nine cytotypes) of the genus Nothoscordum were analyzed using two different techniques to impregnate the nucleolar organizer regions (NORs) with silver nitrate. Both techniques strongly stained NORs, but one of them also stained the proximal region of all chromosomes, suggesting the existence of another group of argentophilic proteins in this region. In species with rDNA sites in acrocentric and metacentric chromosomes, sites located on the short arms of the acrocentric chromosomes were preferentially activated. On the other hand, in species with rDNA sites restricted to the short arms of the acrocentrics, all of them were activated, whereas in those species with sites restricted to the terminal region of metacentric chromosomes, the frequency of active sites was always lower than expected. This indicate that, at least in Nothoscordum, the transcription of an rDNA site is influenced by its chromosomal position, and may explain, at least partially, the strongly non-random distribution of these sites in plant and animal chromosomes.
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Affiliation(s)
- Mariana Báez
- Universidade Federal de Pernambuco, Departamento de Botânica, Laboratório de Citogenética e Evolução de Plantas, Recife, PE, Brazil
| | - Gustavo Souza
- Universidade Federal de Pernambuco, Departamento de Botânica, Laboratório de Citogenética e Evolução de Plantas, Recife, PE, Brazil
| | - Marcelo Guerra
- Universidade Federal de Pernambuco, Departamento de Botânica, Laboratório de Citogenética e Evolução de Plantas, Recife, PE, Brazil
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Warsinger-Pepe N, Li D, Yamashita YM. Regulation of Nucleolar Dominance in Drosophila melanogaster. Genetics 2020; 214:991-1004. [PMID: 32122935 DOI: 10.1534/genetics.119.302471] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 02/26/2020] [Indexed: 12/18/2022] Open
Abstract
In eukaryotic genomes, ribosomal RNA (rRNA) genes exist as tandemly repeated clusters, forming ribosomal DNA (rDNA) loci. Each rDNA locus typically contains hundreds of rRNA genes to meet the high demand of ribosome biogenesis. Nucleolar dominance is a phenomenon whereby individual rDNA loci are entirely silenced or transcribed, and is believed to be a mechanism to control rRNA dosage. Nucleolar dominance was originally noted to occur in interspecies hybrids, and has been shown to occur within a species (i.e., nonhybrid context). However, studying nucleolar dominance within a species has been challenging due to the highly homogenous sequence across rDNA loci. By utilizing single nucleotide polymorphisms between X rDNA and Y rDNA loci in males, as well as sequence variations between two X rDNA loci in females, we conducted a thorough characterization of nucleolar dominance throughout development of Drosophila melanogaster. We demonstrate that nucleolar dominance is a developmentally regulated program that occurs in nonhybrid, wild-type D. melanogaster, where Y rDNA dominance is established during male embryogenesis, whereas females normally do not exhibit dominance between two X rDNA loci. By utilizing various chromosomal complements (e.g., X/Y, X/X, X/X/Y) and a chromosome rearrangement, we show that the short arm of the Y chromosome including the Y rDNA likely contains information that instructs the state of nucleolar dominance. Our study begins to reveal the mechanisms underlying the selection of rDNA loci for activation/silencing in nucleolar dominance in the context of nonhybrid D. melanogaster.
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Luo L, Ando S, Sakamoto Y, Suzuki T, Takahashi H, Ishibashi N, Kojima S, Kurihara D, Higashiyama T, Yamamoto KT, Matsunaga S, Machida C, Sasabe M, Machida Y. The formation of perinucleolar bodies is important for normal leaf development and requires the zinc-finger DNA-binding motif in Arabidopsis ASYMMETRIC LEAVES2. Plant J 2020; 101:1118-1134. [PMID: 31639235 PMCID: PMC7155070 DOI: 10.1111/tpj.14579] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/30/2019] [Accepted: 10/08/2019] [Indexed: 05/27/2023]
Abstract
In Arabidopsis, the ASYMMETRIC LEAVES2 (AS2) protein plays a key role in the formation of flat symmetric leaves via direct repression of the abaxial gene ETT/ARF3. AS2 encodes a plant-specific nuclear protein that contains the AS2/LOB domain, which includes a zinc-finger (ZF) motif that is conserved in the AS2/LOB family. We have shown that AS2 binds to the coding DNA of ETT/ARF3, which requires the ZF motif. AS2 is co-localized with AS1 in perinucleolar bodies (AS2 bodies). To identify the amino acid signals in AS2 required for formation of AS2 bodies and function(s) in leaf formation, we constructed recombinant DNAs that encoded mutant AS2 proteins fused to yellow fluorescent protein. We examined the subcellular localization of these proteins in cells of cotyledons and leaf primordia of transgenic plants and cultured cells. The amino acid signals essential for formation of AS2 bodies were located within and adjacent to the ZF motif. Mutant AS2 that failed to form AS2 bodies also failed to rescue the as2-1 mutation. Our results suggest the importance of the formation of AS2 bodies and the nature of interactions of AS2 with its target DNA and nucleolar factors including NUCLEOLIN1. The partial overlap of AS2 bodies with perinucleolar chromocenters with condensed ribosomal RNA genes implies a correlation between AS2 bodies and the chromatin state. Patterns of AS2 bodies in cells during interphase and mitosis in leaf primordia were distinct from those in cultured cells, suggesting that the formation and distribution of AS2 bodies are developmentally modulated in plants.
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Affiliation(s)
- Lilan Luo
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
- Present address:
Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing100101China
| | - Sayuri Ando
- Graduate School of Bioscience and BiotechnologyChubu UniversityKasugaiAichi487‐8501Japan
| | - Yuki Sakamoto
- Department of Applied Biological ScienceFaculty of Science and TechnologyTokyo University of ScienceNodaChiba278‐8510Japan
- Department of Biological SciencesGraduate School of ScienceOsaka University1‐1 Machikaneyama‐choToyonakaOsaka560‐0043Japan
| | - Takanori Suzuki
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
- Central Research InstituteIshihara Sangyo Kaisha, Ltd.2‐3‐1 Nishi‐ShibukawaKusatsuShiga525‐0025Japan
| | - Hiro Takahashi
- Graduate School of Medical SciencesKanazawa UniversityKakuma‐machiKanazawaIshikawa920‐1192Japan
| | - Nanako Ishibashi
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
| | - Shoko Kojima
- Graduate School of Bioscience and BiotechnologyChubu UniversityKasugaiAichi487‐8501Japan
| | - Daisuke Kurihara
- JST, PRESTOFuro‐cho, Chikusa‐kuNagoyaAichi464‐8601Japan
- Institute of Transformative Bio‐Molecules (ITbM)Nagoya UniversityFuro‐cho, Chiku00sa‐kuNagoyaAichi464‐8601Japan
| | - Tetsuya Higashiyama
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
- Institute of Transformative Bio‐Molecules (ITbM)Nagoya UniversityFuro‐cho, Chiku00sa‐kuNagoyaAichi464‐8601Japan
- Department of Biological SciencesGraduate School of ScienceUniversity of Tokyo7‐3‐1 Hongo, Bukyo‐kuTokyo113‐0033Japan
| | - Kotaro T. Yamamoto
- Division of Biological SciencesFaculty of ScienceHokkaido UniversitySapporo060‐0810Japan
| | - Sachihiro Matsunaga
- Department of Applied Biological ScienceFaculty of Science and TechnologyTokyo University of ScienceNodaChiba278‐8510Japan
| | - Chiyoko Machida
- Graduate School of Bioscience and BiotechnologyChubu UniversityKasugaiAichi487‐8501Japan
| | - Michiko Sasabe
- Department of BiologyFaculty of Agriculture and Life ScienceHirosaki University3 Bunkyo‐choHirosaki036‐8561Japan
| | - Yasunori Machida
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaAichi464‐8602Japan
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Glombik M, Bačovský V, Hobza R, Kopecký D. Competition of Parental Genomes in Plant Hybrids. Front Plant Sci 2020; 11:200. [PMID: 32158461 PMCID: PMC7052263 DOI: 10.3389/fpls.2020.00200] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/11/2020] [Indexed: 05/17/2023]
Abstract
Interspecific hybridization represents one of the main mechanisms of plant speciation. Merging of two genomes from different subspecies, species, or even genera is frequently accompanied by whole-genome duplication (WGD). Besides its evolutionary role, interspecific hybridization has also been successfully implemented in multiple breeding programs. Interspecific hybrids combine agronomic traits of two crop species or can be used to introgress specific loci of interests, such as those for resistance against abiotic or biotic stresses. The genomes of newly established interspecific hybrids (both allopolyploids and homoploids) undergo dramatic changes, including chromosome rearrangements, amplifications of tandem repeats, activation of mobile repetitive elements, and gene expression modifications. To ensure genome stability and proper transmission of chromosomes from both parental genomes into subsequent generations, allopolyploids often evolve mechanisms regulating chromosome pairing. Such regulatory systems allow only pairing of homologous chromosomes and hamper pairing of homoeologs. Despite such regulatory systems, several hybrid examples with frequent homoeologous chromosome pairing have been reported. These reports open a way for the replacement of one parental genome by the other. In this review, we provide an overview of the current knowledge of genomic changes in interspecific homoploid and allopolyploid hybrids, with strictly homologous pairing and with relaxed pairing of homoeologs.
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Affiliation(s)
- Marek Glombik
- Institute of Experimental Botany, Czech Academy of Sciences, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czechia
| | - Václav Bačovský
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
| | - Roman Hobza
- Institute of Experimental Botany, Czech Academy of Sciences, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czechia
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
| | - David Kopecký
- Institute of Experimental Botany, Czech Academy of Sciences, Centre of the Region Hana for Biotechnological and Agricultural Research, Olomouc, Czechia
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Matyášek R, Krumpolcová A, Lunerová J, Mikulášková E, Rosselló JA, Kovařík A. Unique Epigenetic Features of Ribosomal RNA Genes (rDNA) in Early Diverging Plants (Bryophytes). Front Plant Sci 2019; 10:1066. [PMID: 31543890 PMCID: PMC6739443 DOI: 10.3389/fpls.2019.01066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 08/06/2019] [Indexed: 05/03/2023]
Abstract
Introduction: In plants, the multicopy genes encoding ribosomal RNA (rDNA) typically exhibit heterochromatic features and high level of DNA methylation. Here, we explored rDNA methylation in early diverging land plants from Bryophyta (15 species, 14 families) and Marchantiophyta (4 species, 4 families). DNA methylation was investigated by methylation-sensitive Southern blot hybridization in all species. We also carried out whole genomic bisulfite sequencing in Polytrichum formosum (Polytrichaceae) and Dicranum scoparium (Dicranaceae) and used available model plant methyloms (Physcomitrella patents and Marchantia polymorpha) to determine rDNA unit-wide methylation patterns. Chromatin structure was analyzed using fluorescence in situ hybridization (FISH) and immunoprecipitation (CHIP) assays. Results: In contrast to seed plants, bryophyte rDNAs were efficiently digested with methylation-sensitive enzymes indicating no or low levels of CG and CHG methylation in these loci. The rDNA methylom analyses revealed variation between species ranging from negligible (<3%, P. formosum, P. patens) to moderate (7 and 17% in M. polymorpha and D. scoparium, respectively) methylation levels. There were no differences between coding and noncoding parts of rDNA units and between gametophyte and sporophyte tissues. However, major satellite repeat and transposable elements were heavily methylated in P. formosum and D. scoparium. In P. formosum rDNA, the euchromatic H3K4m3 and heterochromatic H3K9m2 histone marks were nearly balanced contrasting the angiosperms data where H3K9m2 typically dominates rDNA chromatin. In moss interphase nuclei, rDNA was localized at the nucleolar periphery and its condensation level was high. Conclusions: Unlike seed plants, the rRNA genes seem to escape global methylation machinery in bryophytes. Distinct epigenetic features may be related to rDNA expression and the physiology of these early diverging plants that exist in haploid state for most of their life cycles.
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Affiliation(s)
- Roman Matyášek
- Department of Molecular Epigenetics, Institute of Biophysics of the Czech Academy of Sciences, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
| | - Alice Krumpolcová
- Department of Molecular Epigenetics, Institute of Biophysics of the Czech Academy of Sciences, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
| | - Jana Lunerová
- Department of Molecular Epigenetics, Institute of Biophysics of the Czech Academy of Sciences, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
| | - Eva Mikulášková
- Department of Botany and Zoology, Masaryk University, Brno, Czechia
| | - Josep A. Rosselló
- Jardín Botánico, ICBiBE-Unidad Asociada CSIC, Universidad de Valencia, Valencia, Spain
| | - Aleš Kovařík
- Department of Molecular Epigenetics, Institute of Biophysics of the Czech Academy of Sciences, Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
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48
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Sáez-Vásquez J, Delseny M. Ribosome Biogenesis in Plants: From Functional 45S Ribosomal DNA Organization to Ribosome Assembly Factors. Plant Cell 2019; 31:1945-1967. [PMID: 31239391 PMCID: PMC6751116 DOI: 10.1105/tpc.18.00874] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 05/28/2019] [Accepted: 06/25/2019] [Indexed: 05/11/2023]
Abstract
The transcription of 18S, 5.8S, and 18S rRNA genes (45S rDNA), cotranscriptional processing of pre-rRNA, and assembly of mature rRNA with ribosomal proteins are the linchpins of ribosome biogenesis. In yeast (Saccharomyces cerevisiae) and animal cells, hundreds of pre-rRNA processing factors have been identified and their involvement in ribosome assembly determined. These studies, together with structural analyses, have yielded comprehensive models of the pre-40S and pre-60S ribosome subunits as well as the largest cotranscriptionally assembled preribosome particle: the 90S/small subunit processome. Here, we present the current knowledge of the functional organization of 45S rDNA, pre-rRNA transcription, rRNA processing activities, and ribosome assembly factors in plants, focusing on data from Arabidopsis (Arabidopsis thaliana). Based on yeast and mammalian cell studies, we describe the ribonucleoprotein complexes and RNA-associated activities and discuss how they might specifically affect the production of 40S and 60S subunits. Finally, we review recent findings concerning pre-rRNA processing pathways and a novel mechanism involved in a ribosome stress response in plants.
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Affiliation(s)
- Julio Sáez-Vásquez
- CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, 66860 Perpignan, France, and Universite Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, F-66860 Perpignan, France
| | - Michel Delseny
- CNRS, Laboratoire Génome et Développement des Plantes, UMR 5096, 66860 Perpignan, France, and Universite Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, F-66860 Perpignan, France
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Abstract
The nucleolus is the largest substructure in the nucleus, where ribosome biogenesis takes place, and forms around the nucleolar organizer regions (NORs) that comprise ribosomal RNA (rRNA) genes. Each cell contains hundreds of rRNA genes, which are organized in three distinct chromatin and transcriptional states—silent, inactive and active. Increasing evidence indicates that the role of the nucleolus and rRNA genes goes beyond the control of ribosome biogenesis. Recent results highlighted the nucleolus as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we aim to describe the crosstalk between the nucleolus and the rest of the genome and how distinct rRNA gene chromatin states affect nucleolus structure and are implicated in genome stability, genome architecture, and cell fate decision.
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50
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He S, Vickers M, Zhang J, Feng X. Natural depletion of histone H1 in sex cells causes DNA demethylation, heterochromatin decondensation and transposon activation. eLife 2019; 8:42530. [PMID: 31135340 PMCID: PMC6594752 DOI: 10.7554/elife.42530] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 05/26/2019] [Indexed: 01/09/2023] Open
Abstract
Transposable elements (TEs), the movement of which can damage the genome, are epigenetically silenced in eukaryotes. Intriguingly, TEs are activated in the sperm companion cell - vegetative cell (VC) - of the flowering plant Arabidopsis thaliana. However, the extent and mechanism of this activation are unknown. Here we show that about 100 heterochromatic TEs are activated in VCs, mostly by DEMETER-catalyzed DNA demethylation. We further demonstrate that DEMETER access to some of these TEs is permitted by the natural depletion of linker histone H1 in VCs. Ectopically expressed H1 suppresses TEs in VCs by reducing DNA demethylation and via a methylation-independent mechanism. We demonstrate that H1 is required for heterochromatin condensation in plant cells and show that H1 overexpression creates heterochromatic foci in the VC progenitor cell. Taken together, our results demonstrate that the natural depletion of H1 during male gametogenesis facilitates DEMETER-directed DNA demethylation, heterochromatin relaxation, and TE activation.
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Affiliation(s)
- Shengbo He
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom
| | - Martin Vickers
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom
| | - Jingyi Zhang
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom
| | - Xiaoqi Feng
- Department of Cell and Developmental Biology, John Innes Centre, Norwich, United Kingdom
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