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Merker L, Feller L, Dorn A, Puchta H. Deficiency of both classical and alternative end-joining pathways leads to a synergistic defect in double-strand break repair but not to an increase in homology-dependent gene targeting in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:242-254. [PMID: 38179887 DOI: 10.1111/tpj.16604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 10/13/2023] [Accepted: 12/12/2023] [Indexed: 01/06/2024]
Abstract
In eukaryotes, double-strand breaks (DSBs) are either repaired by homologous recombination (HR) or non-homologous end-joining (NHEJ). In somatic plant cells, HR is very inefficient. Therefore, the vast majority of DSBs are repaired by two different pathways of NHEJ. The classical (cNHEJ) pathway depends on the heterodimer KU70/KU80, while polymerase theta (POLQ) is central to the alternative (aNHEJ) pathway. Surprisingly, Arabidopsis plants are viable, even when both pathways are impaired. However, they exhibit severe growth retardation and reduced fertility. Analysis of mitotic anaphases indicates that the double mutant is characterized by a dramatic increase in chromosome fragmentation due to defective DSB repair. In contrast to the single mutants, the double mutant was found to be highly sensitive to the DSB-inducing genotoxin bleomycin. Thus, both pathways can complement for each other efficiently in DSB repair. We speculated that in the absence of both NHEJ pathways, HR might be enhanced. This would be especially attractive for gene targeting (GT) in which predefined changes are introduced using a homologous template. Unexpectedly, the polq single mutant as well as the double mutant showed significantly lower GT frequencies in comparison to wildtype plants. Accordingly, we were able to show that elimination of both NHEJ pathways does not pose an attractive approach for Agrobacterium-mediated GT. However, our results clearly indicate that a loss of cNHEJ leads to an increase in GT frequency, which is especially drastic and attractive for practical applications, in which the in planta GT strategy is used.
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Affiliation(s)
- Laura Merker
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
| | - Laura Feller
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
| | - Annika Dorn
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
| | - Holger Puchta
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
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2
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Vladejić J, Kovacik M, Zwyrtková J, Szurman-Zubrzycka M, Doležel J, Pecinka A. Zeocin-induced DNA damage response in barley and its dependence on ATR. Sci Rep 2024; 14:3119. [PMID: 38326519 PMCID: PMC10850495 DOI: 10.1038/s41598-024-53264-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 01/30/2024] [Indexed: 02/09/2024] Open
Abstract
DNA damage response (DDR) is an essential mechanism by which living organisms maintain their genomic stability. In plants, DDR is important also for normal growth and yield. Here, we explored the DDR of a temperate model crop barley (Hordeum vulgare) at the phenotypic, physiological, and transcriptomic levels. By a series of in vitro DNA damage assays using the DNA strand break (DNA-SB) inducing agent zeocin, we showed reduced root growth and expansion of the differentiated zone to the root tip. Genome-wide transcriptional profiling of barley wild-type and plants mutated in DDR signaling kinase ATAXIA TELANGIECTASIA MUTATED AND RAD3-RELATED (hvatr.g) revealed zeocin-dependent, ATR-dependent, and zeocin-dependent/ATR-independent transcriptional responses. Transcriptional changes were scored also using the newly developed catalog of 421 barley DDR genes with the phylogenetically-resolved relationships of barley SUPRESSOR OF GAMMA 1 (SOG1) and SOG1-LIKE (SGL) genes. Zeocin caused up-regulation of specific DDR factors and down-regulation of cell cycle and histone genes, mostly in an ATR-independent manner. The ATR dependency was obvious for some factors associated with DDR during DNA replication and for many genes without an obvious connection to DDR. This provided molecular insight into the response to DNA-SB induction in the large and complex barley genome.
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Affiliation(s)
- Jovanka Vladejić
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czechia
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Martin Kovacik
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czechia
- Department of Cell Biology and Genetics, Faculty of Science, Palacký University, Olomouc, Czechia
| | - Jana Zwyrtková
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czechia
| | - Miriam Szurman-Zubrzycka
- Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Jaroslav Doležel
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czechia
| | - Ales Pecinka
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czechia.
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3
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Schubert I. Macromutations Yielding Karyotype Alterations (and the Process(es) behind Them) Are the Favored Route of Carcinogenesis and Speciation. Cancers (Basel) 2024; 16:554. [PMID: 38339305 PMCID: PMC10854648 DOI: 10.3390/cancers16030554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/12/2024] Open
Abstract
It is argued that carcinogenesis and speciation are evolutionary events which are based on changes in the 'karyotypic code' through a phase of 'genome instability', followed by a bottleneck of selection for the viability and adaptability of the initial cells. Genomic (i.e., chromosomal) instability is caused by (massive) DNA breakage and the subsequent mis-repair of DNA double-strand breaks (DSBs) resulting in various chromosome rearrangements. Potential tumor cells are selected for rapid somatic proliferation. Cells eventually yielding a novel species need not only to be viable and proliferation proficient, but also to have a balanced genome which, after passing meiosis as another bottleneck and fusing with an identical gamete, can result in a well-adapted organism. Such new organisms should be genetically or geographically isolated from the ancestral population and possess or develop an at least partial sexual barrier.
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Affiliation(s)
- Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 04644 Gatersleben, Germany
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4
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Saini H, Thakur R, Gill R, Tyagi K, Goswami M. CRISPR/Cas9-gene editing approaches in plant breeding. GM CROPS & FOOD 2023; 14:1-17. [PMID: 37725519 PMCID: PMC10512805 DOI: 10.1080/21645698.2023.2256930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 09/05/2023] [Indexed: 09/21/2023]
Abstract
CRISPR/Cas9 gene editing system is recently developed robust genome editing technology for accelerating plant breeding. Various modifications of this editing system have been established for adaptability in plant varieties as well as for its improved efficiency and portability. This review provides an in-depth look at the various strategies for synthesizing gRNAs for efficient delivery in plant cells, including chemical synthesis and in vitro transcription. It also covers traditional analytical tools and emerging developments in detection methods to analyze CRISPR/Cas9 mediated mutation in plant breeding. Additionally, the review outlines the various analytical tools which are used to detect and analyze CRISPR/Cas9 mediated mutations, such as next-generation sequencing, restriction enzyme analysis, and southern blotting. Finally, the review discusses emerging detection methods, including digital PCR and qPCR. Hence, CRISPR/Cas9 has great potential for transforming agriculture and opening avenues for new advancements in the system for gene editing in plants.
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Affiliation(s)
- Himanshu Saini
- School of Applied Natural Science, Adama Science and Technology University, Adama, Ethiopia
- School of Agriculture, Forestry & Fisheries, Himgiri Zee University, Dehradun, Uttarakhand, India
| | - Rajneesh Thakur
- Department of Plant Pathology, Dr Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India
| | - Rubina Gill
- Department of Agronomy, School of Agriculture, Lovely professional university, Phagwara, Punjab, India
| | - Kalpana Tyagi
- Division of Genetics and Tree Improvement, Forest Research Institute, Dehradun, Uttarakhand, India
| | - Manika Goswami
- Department of Fruit Science, Dr Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India
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5
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The Interplay between the Cellular Response to DNA Double-Strand Breaks and Estrogen. Cells 2022; 11:cells11193097. [PMID: 36231059 PMCID: PMC9563627 DOI: 10.3390/cells11193097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/28/2022] [Accepted: 09/29/2022] [Indexed: 11/17/2022] Open
Abstract
Cancer development is often connected to impaired DNA repair and DNA damage signaling pathways. The presence of DNA damage in cells activates DNA damage response, which is a complex cellular signaling network that includes DNA repair, activation of the cell cycle checkpoints, cellular senescence, and apoptosis. DNA double-strand breaks (DSBs) are toxic lesions that are mainly repaired by the non-homologous end joining and homologous recombination repair (HRR) pathways. Estrogen-dependent cancers, like breast and ovarian cancers, are frequently associated with mutations in genes that play a role in HRR. The female sex hormone estrogen binds and activates the estrogen receptors (ERs), ERα, ERβ and G-protein-coupled ER 1 (GPER1). ERα drives proliferation, while ERβ inhibits cell growth. Estrogen regulates the transcription, stability and activity of numerus DDR factors and DDR factors in turn modulate ERα expression, stability and transcriptional activity. Additionally, estrogen stimulates DSB formation in cells as part of its metabolism and proliferative effect. In this review, we will present an overview on the crosstalk between estrogen and the cellular response to DSBs. We will discuss how estrogen regulates DSB signaling and repair, and how DDR factors modulate the expression, stability and activity of estrogen. We will also discuss how the regulation of HRR genes by estrogen promotes the development of estrogen-dependent cancers.
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6
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Ma L, Kong F, Sun K, Wang T, Guo T. From Classical Radiation to Modern Radiation: Past, Present, and Future of Radiation Mutation Breeding. Front Public Health 2022; 9:768071. [PMID: 34993169 PMCID: PMC8725632 DOI: 10.3389/fpubh.2021.768071] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/15/2021] [Indexed: 12/12/2022] Open
Abstract
Radiation mutation breeding has been used for nearly 100 years and has successfully improved crops by increasing genetic variation. Global food production is facing a series of challenges, such as rapid population growth, environmental pollution and climate change. How to feed the world's enormous human population poses great challenges to breeders. Although advanced technologies, such as gene editing, have provided effective ways to breed varieties, by editing a single or multiple specific target genes, enhancing germplasm diversity through mutation is still indispensable in modern and classical radiation breeding because it is more likely to produce random mutations in the whole genome. In this short review, the current status of classical radiation, accelerated particle and space radiation mutation breeding is discussed, and the molecular mechanisms of radiation-induced mutation are demonstrated. This review also looks into the future development of radiation mutation breeding, hoping to deepen our understanding and provide new vitality for the further development of radiation mutation breeding.
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Affiliation(s)
- Liqiu Ma
- Department of Nuclear Physics, China Institute of Atomic Energy, Beijing, China.,National Innovation Center of Radiation Application, Beijing, China
| | - Fuquan Kong
- Department of Nuclear Physics, China Institute of Atomic Energy, Beijing, China.,National Innovation Center of Radiation Application, Beijing, China
| | - Kai Sun
- National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangdong, China
| | - Ting Wang
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Tao Guo
- National Engineering Research Center of Plant Space Breeding, South China Agricultural University, Guangdong, China
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7
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Kitamura S, Satoh K, Oono Y. Detection and characterization of genome-wide mutations in M1 vegetative cells of gamma-irradiated Arabidopsis. PLoS Genet 2022; 18:e1009979. [PMID: 35051177 PMCID: PMC8775353 DOI: 10.1371/journal.pgen.1009979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 12/04/2021] [Indexed: 11/20/2022] Open
Abstract
Radiation-induced mutations have been detected by whole-genome sequencing analyses of self-pollinated generations of mutagenized plants. However, large DNA alterations and mutations in non-germline cells were likely missed. In this study, in order to detect various types of mutations in mutagenized M1 plants, anthocyanin pigmentation was used as a visible marker of mutations. Arabidopsis seeds heterozygous for the anthocyanin biosynthetic genes were irradiated with gamma-rays. Anthocyanin-less vegetative sectors resulting from a loss of heterozygosity were isolated from the gamma-irradiated M1 plants. The whole-genome sequencing analysis of the sectors detected various mutations, including structural variations (SVs) and large deletions (≥100 bp), both of which have been less characterized in the previous researches using gamma-irradiated plant genomes of M2 or later generations. Various types of rejoined sites were found in SVs, including no-insertion/deletion (indel) sites, only-deletion sites, only-insertion sites, and indel sites, but the rejoined sites with 0–5 bp indels represented most of the SVs. Examinations of the junctions of rearrangements (SVs and large deletions), medium deletions (10–99 bp), and small deletions (2–9 bp) revealed unique features (i.e., frequency of insertions and microhomology) at the rejoined sites. These results suggest that they were formed preferentially via different processes. Additionally, mutations that occurred in putative single M1 cells were identified according to the distribution of their allele frequency. The estimated mutation frequencies and spectra of the M1 cells were similar to those of previously analyzed M2 cells, with the exception of the greater proportion of rearrangements in the M1 cells. These findings suggest there are no major differences in the small mutations (<100 bp) between vegetative and germline cells. Thus, this study generated valuable information that may help clarify the nature of gamma-irradiation-induced mutations and their occurrence in cells that develop into vegetative or reproductive tissues. Mutations that occur in plant genome are not only related to plant evolution and speciation in nature, and also useful to identify novel gene functions and to develop new cultivars. Ionizing radiations induce various types of mutations throughout genomes in individual cells of an irradiated/mutagenized plant. However, current knowledge on radiation-induced genome-wide mutations in plants relied on the analyses of self-pollinated generations (M2 or later generations) of the mutagenized plants (M1 generation). Thus, mutations that are hardly transmitted to the next generation and those occurred in non-germline cells could not be investigated. Here, using anthocyanin pigmentation as a visible marker to reduce the genomic complexity in M1 plants, we achieved reliable detection of radiation-induced genome-wide mutations. We demonstrated that rearrangements, which were hardly detected in previous analyses using M2 genomes, occurred substantially often in gamma-irradiated M1 cells. We also revealed that mutation profile of the M1 cells was comparable with that of M2 genomes reported in previous analyses, except for the higher proportion of rearrangements in the M1 genome. Together with unique features at rejoined sites of rearrangements, medium deletions, and small deletions in the M1 genome, our findings are helpful to know the nature of genome-wide mutations induced by gamma-irradiation.
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Affiliation(s)
- Satoshi Kitamura
- Project “Ion Beam Mutagenesis”, Department of Radiation-Applied Biology Research, Takasaki Advanced Radiation Research Institute, National Institutes for Quantum Science and Technology, Takasaki, Japan
- * E-mail:
| | - Katsuya Satoh
- Project “Ion Beam Mutagenesis”, Department of Radiation-Applied Biology Research, Takasaki Advanced Radiation Research Institute, National Institutes for Quantum Science and Technology, Takasaki, Japan
| | - Yutaka Oono
- Project “Ion Beam Mutagenesis”, Department of Radiation-Applied Biology Research, Takasaki Advanced Radiation Research Institute, National Institutes for Quantum Science and Technology, Takasaki, Japan
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8
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Targeted Inter-Homologs Recombination in Arabidopsis Euchromatin and Heterochromatin. Int J Mol Sci 2021; 22:ijms222212096. [PMID: 34829981 PMCID: PMC8622013 DOI: 10.3390/ijms222212096] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 12/20/2022] Open
Abstract
Homologous recombination (HR) typically occurs during meiosis between homologs, at a few unplanned locations along the chromosomes. In this study, we tested whether targeted recombination between homologous chromosomes can be achieved via Clustered Regulatory Interspaced Short Palindromic Repeat associated protein Cas9 (CRISPR-Cas9)-induced DNA double-strand break (DSB) repair in Arabidopsis thaliana. Our experimental system includes targets for DSB induction in euchromatic and heterochromatic genomic regions of hybrid F1 plants, in one or both parental chromosomes, using phenotypic and molecular markers to measure Non-Homologous End Joining and HR repair. We present a series of evidence showing that targeted DSBs can be repaired via HR using a homologous chromosome as the template in various chromatin contexts including in pericentric regions. Targeted crossover was rare, but gene conversion events were the most frequent outcome of HR and were found in both “hot and cold” regions. The length of the conversion tracts was variable, ranging from 5 to 7505 bp. In addition, a typical feature of these tracks was that they often were interrupted. Our findings pave the way for the use of targeted gene-conversion for precise breeding.
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9
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Lawrenson T, Hinchliffe A, Clarke M, Morgan Y, Harwood W. In-planta Gene Targeting in Barley Using Cas9 With and Without Geminiviral Replicons. Front Genome Ed 2021; 3:663380. [PMID: 34713258 PMCID: PMC8525372 DOI: 10.3389/fgeed.2021.663380] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/29/2021] [Indexed: 11/13/2022] Open
Abstract
Advances in the use of RNA-guided Cas9-based genome editing in plants have been rapid over the last few years. A desirable application of genome editing is gene targeting (GT), as it allows a wide range of precise modifications; however, this remains inefficient especially in key crop species. Here, we describe successful, heritable gene targeting in barley at the target site of Cas9 using an in-planta strategy but fail to achieve the same using a wheat dwarf virus replicon to increase the copy number of the repair template. Without the replicon, we were able to delete 150 bp of the coding sequence of our target gene whilst simultaneously fusing in-frame mCherry in its place. Starting from 14 original transgenic plants, two plants appeared to have the required gene targeting event. From one of these T0 plants, three independent gene targeting events were identified, two of which were heritable. When the replicon was included, 39 T0 plants were produced and shown to have high copy numbers of the repair template. However, none of the 17 lines screened in T1 gave rise to significant or heritable gene targeting events despite screening twice the number of plants in T1 compared with the non-replicon strategy. Investigation indicated that high copy numbers of repair template created by the replicon approach cause false-positive PCR results which are indistinguishable at the sequence level to true GT events in junction PCR screens widely used in GT studies. In the successful non-replicon approach, heritable gene targeting events were obtained in T1, and subsequently, the T-DNA was found to be linked to the targeted locus. Thus, physical proximity of target and donor sites may be a factor in successful gene targeting.
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Affiliation(s)
- Tom Lawrenson
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | | | - Martha Clarke
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Yvie Morgan
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Wendy Harwood
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
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10
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Wang X, Morton JA, Pellicer J, Leitch IJ, Leitch AR. Genome downsizing after polyploidy: mechanisms, rates and selection pressures. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 107:1003-1015. [PMID: 34077584 DOI: 10.1111/tpj.15363] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/07/2021] [Accepted: 05/13/2021] [Indexed: 05/20/2023]
Abstract
An analysis of over 10 000 plant genome sizes (GSs) indicates that most species have smaller genomes than expected given the incidence of polyploidy in their ancestries, suggesting selection for genome downsizing. However, comparing ancestral GS with the incidence of ancestral polyploidy suggests that the rate of DNA loss following polyploidy is likely to have been very low (4-70 Mb/million years, 4-482 bp/generation). This poses a problem. How might such small DNA losses be visible to selection, overcome the power of genetic drift and drive genome downsizing? Here we explore that problem, focussing on the role that double-strand break (DSB) repair pathways (non-homologous end joining and homologous recombination) may have played. We also explore two hypotheses that could explain how selection might favour genome downsizing following polyploidy: to reduce (i) nitrogen (N) and phosphate (P) costs associated with nucleic acid synthesis in the nucleus and the transcriptome and (ii) the impact of scaling effects of GS on cell size, which influences CO2 uptake and water loss. We explore the hypothesis that losses of DNA must be fastest in early polyploid generations. Alternatively, if DNA loss is a more continuous process over evolutionary time, then we propose it is a byproduct of selection elsewhere, such as limiting the damaging activity of repetitive DNA. If so, then the impact of GS on photosynthesis, water use efficiency and/or nutrient costs at the nucleus level may be emergent properties, which have advantages, but not ones that could have been selected for over generational timescales.
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Affiliation(s)
- Xiaotong Wang
- Royal Botanic Gardens, Kew, Surrey, TW9 3AB, UK
- Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Joseph A Morton
- Royal Botanic Gardens, Kew, Surrey, TW9 3AB, UK
- Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Jaume Pellicer
- Royal Botanic Gardens, Kew, Surrey, TW9 3AB, UK
- Institut Botànic de Barcelona (IBB, CSIC-Ajuntament de Barcelona), Passeig del Migdia sn, Barcelona, 08038, Spain
| | | | - Andrew R Leitch
- Queen Mary University of London, Mile End Road, London, E1 4NS, UK
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11
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Čermák T. Sequence modification on demand: search and replace tools for precise gene editing in plants. Transgenic Res 2021; 30:353-379. [PMID: 34086167 DOI: 10.1007/s11248-021-00253-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/05/2021] [Indexed: 12/26/2022]
Abstract
Until recently, our ability to generate allelic diversity in plants was limited to introduction of variants from domesticated and wild species by breeding via uncontrolled recombination or the use of chemical and physical mutagens-processes that are lengthy and costly or lack specificity, respectively. Gene editing provides a faster and more precise way to create new variation, although its application in plants has been dominated by the creation of short insertion and deletion mutations leading to loss of gene function, mostly due to the dependence of editing outcomes on DNA repair pathway choices intrinsic to higher eukaryotes. Other types of edits such as point mutations and precise and pre-designed targeted sequence insertions have rarely been implemented, despite providing means to modulate the expression of target genes or to engineer the function and stability of their protein products. Several advancements have been developed in recent years to facilitate custom editing by regulation of repair pathway choices or by taking advantage of alternative types of DNA repair. We have seen the advent of novel gene editing tools that are independent of DNA double-strand break repair, and methods completely independent of host DNA repair processes are being increasingly explored. With the aim to provide a comprehensive review of the state-of-the-art methodology for allele replacement in plants, I discuss the adoption of these improvements for plant genome engineering.
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12
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Ohtsuki N, Kizawa K, Mori A, Nishizawa-Yokoi A, Komatsuda T, Yoshida H, Hayakawa K, Toki S, Saika H. Precise Genome Editing in miRNA Target Site via Gene Targeting and Subsequent Single-Strand-Annealing-Mediated Excision of the Marker Gene in Plants. Front Genome Ed 2021; 2:617713. [PMID: 34713238 PMCID: PMC8525353 DOI: 10.3389/fgeed.2020.617713] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 12/10/2020] [Indexed: 12/31/2022] Open
Abstract
Gene targeting (GT) enables precise genome modification-e.g., the introduction of base substitutions-using donor DNA as a template. Combined with clean excision of the selection marker used to select GT cells, GT is expected to become a standard, generally applicable, base editing system. Previously, we demonstrated marker excision via a piggyBac transposon from GT-modified loci in rice. However, piggyBac-mediated marker excision has the limitation that it recognizes only the sequence TTAA. Recently, we proposed a novel and universal precise genome editing system consisting of GT with subsequent single-strand annealing (SSA)-mediated marker excision, which has, in principle, no limitation of target sequences. In this study, we introduced base substitutions into the microRNA miR172 target site of the OsCly1 gene-an ortholog of the barley Cleistogamy1 gene involved in cleistogamous flowering. To ensure efficient SSA, the GT vector harbors 1.2-kb overlapped sequences at both ends of a selection marker. The frequency of positive-negative selection-mediated GT using the vector with overlapped sequences was comparable with that achieved using vectors for piggyBac-mediated marker excision without overlapped sequences, with the frequency of SSA-mediated marker excision calculated as ~40% in the T0 generation. This frequency is thought to be adequate to produce marker-free cells, although it is lower than that achieved with piggyBac-mediated marker excision, which approaches 100%. To date, introduction of precise substitutions in discontinuous multiple bases of a targeted gene using base editors and the prime editing system based on CRISPR/Cas9 has been quite difficult. Here, using GT and our SSA-mediated marker excision system, we succeeded in the precise base substitution not only of single bases but also of artificial discontinuous multiple bases in the miR172 target site of the OsCly1 gene. Precise base substitution of miRNA target sites in target genes using this precise genome editing system will be a powerful tool in the production of valuable crops with improved traits.
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Affiliation(s)
- Namie Ohtsuki
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | | | - Akiko Mori
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | - Ayako Nishizawa-Yokoi
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
- Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), Kawaguchi, Japan
| | | | - Hitoshi Yoshida
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
| | | | - Seiichi Toki
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
- Graduate School of Nanobioscience, Yokohama City University, Yokohama, Japan
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan
| | - Hiroaki Saika
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Japan
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13
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Bariah I, Keidar-Friedman D, Kashkush K. Identification and characterization of large-scale genomic rearrangements during wheat evolution. PLoS One 2020; 15:e0231323. [PMID: 32287287 PMCID: PMC7156093 DOI: 10.1371/journal.pone.0231323] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 03/20/2020] [Indexed: 12/25/2022] Open
Abstract
Following allopolyploidization, nascent polyploid wheat species react with massive genomic rearrangements, including deletion of transposable element-containing sequences. While such massive rearrangements are considered to be a prominent process in wheat genome evolution and speciation, their structure, extent, and underlying mechanisms remain poorly understood. In this study, we retrieved ~3500 insertions of a specific variant of Fatima, one of the most dynamic gypsy long-terminal repeat retrotransposons in wheat from the recently available high-quality genome drafts of Triticum aestivum (bread wheat) and Triticum turgidum ssp. dicoccoides or wild emmer, the allotetraploid mother of all modern wheats. The dynamic nature of Fatima facilitated the identification of large (i.e., up to ~ 1 million bases) Fatima-containing insertions/deletions (indels) upon comparison of bread wheat and wild emmer genomes. We characterized 11 such indels using computer-assisted analysis followed by PCR validation, and found that they might have occurred via unequal intra-strand recombination or double-strand break (DSB) events. Additionally, we observed one case of introgression of novel DNA fragments from an unknown source into the wheat genome. Our data thus indicate that massive large-scale DNA rearrangements might play a prominent role in wheat speciation.
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Affiliation(s)
- Inbar Bariah
- Department of Life Sciences, Ben-Gurion University, Beer-Sheva, Israel
| | | | - Khalil Kashkush
- Department of Life Sciences, Ben-Gurion University, Beer-Sheva, Israel
- * E-mail:
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14
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Trimidal SG, Benjamin R, Bae JE, Han MV, Kong E, Singer A, Williams TS, Yang B, Schiller MR. Can Designer Indels Be Tailored by Gene Editing?: Can Indels Be Customized? Bioessays 2019; 41:e1900126. [PMID: 31693213 PMCID: PMC7202862 DOI: 10.1002/bies.201900126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/01/2019] [Indexed: 12/23/2022]
Abstract
Genome editing with engineered nucleases (GEENs) introduce site-specific DNA double-strand breaks (DSBs) and repairs DSBs via nonhomologous end-joining (NHEJ) pathways that eventually create indels (insertions/deletions) in a genome. Whether the features of indels resulting from gene editing could be customized is asked. A review of the literature reveals how gene editing technologies via NHEJ pathways impact gene editing. The survey consolidates a body of literature that suggests that the type (insertion, deletion, and complex) and the approximate length of indel edits can be somewhat customized with different GEENs and by manipulating the expression of key NHEJ genes. Structural data suggest that binding of GEENs to DNA may interfere with binding of key components of DNA repair complexes, favoring either classical- or alternative-NHEJ. The hypotheses have some limitations, but if validated, will enable scientists to better control indel makeup, holding promise for basic science and clinical applications of gene editing. Also see the video abstract here https://youtu.be/vTkJtUsLi3w.
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Affiliation(s)
- Sara G Trimidal
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Ronald Benjamin
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Ji Eun Bae
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Mira V Han
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Elizabeth Kong
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Aaron Singer
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Tyler S Williams
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Bing Yang
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
| | - Martin R Schiller
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
- Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
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15
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Durut N, Mittelsten Scheid O. The Role of Noncoding RNAs in Double-Strand Break Repair. FRONTIERS IN PLANT SCIENCE 2019; 10:1155. [PMID: 31611891 PMCID: PMC6776598 DOI: 10.3389/fpls.2019.01155] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 08/23/2019] [Indexed: 06/10/2023]
Abstract
Genome stability is constantly threatened by DNA lesions generated by different environmental factors as well as endogenous processes. If not properly and timely repaired, damaged DNA can lead to mutations or chromosomal rearrangements, well-known reasons for genetic diseases or cancer in mammals, or growth abnormalities and/or sterility in plants. To prevent deleterious consequences of DNA damage, a sophisticated system termed DNA damage response (DDR) detects DNA lesions and initiates DNA repair processes. In addition to many well-studied canonical proteins involved in this process, noncoding RNA (ncRNA) molecules have recently been discovered as important regulators of the DDR pathway, extending the broad functional repertoire of ncRNAs to the maintenance of genome stability. These ncRNAs are mainly connected with double-strand breaks (DSBs), the most dangerous type of DNA lesions. The possibility to intentionally generate site-specific DSBs in the genome with endonucleases constitutes a powerful tool to study, in vivo, how DSBs are processed and how ncRNAs participate in this crucial event. In this review, we will summarize studies reporting the different roles of ncRNAs in DSB repair and discuss how genome editing approaches, especially CRISPR/Cas systems, can assist DNA repair studies. We will summarize knowledge concerning the functional significance of ncRNAs in DNA repair and their contribution to genome stability and integrity, with a focus on plants.
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16
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Koeppel I, Hertig C, Hoffie R, Kumlehn J. Cas Endonuclease Technology-A Quantum Leap in the Advancement of Barley and Wheat Genetic Engineering. Int J Mol Sci 2019; 20:ijms20112647. [PMID: 31146387 PMCID: PMC6600890 DOI: 10.3390/ijms20112647] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 05/24/2019] [Accepted: 05/24/2019] [Indexed: 12/21/2022] Open
Abstract
Domestication and breeding have created productive crops that are adapted to the climatic conditions of their growing regions. Initially, this process solely relied on the frequent occurrence of spontaneous mutations and the recombination of resultant gene variants. Later, treatments with ionizing radiation or mutagenic chemicals facilitated dramatically increased mutation rates, which remarkably extended the genetic diversity of crop plants. However, a major drawback of conventionally induced mutagenesis is that genetic alterations occur simultaneously across the whole genome and at very high numbers per individual plant. By contrast, the newly emerging Cas endonuclease technology allows for the induction of mutations at user-defined positions in the plant genome. In fundamental and breeding-oriented research, this opens up unprecedented opportunities for the elucidation of gene functions and the targeted improvement of plant performance. This review covers historical aspects of the development of customizable endonucleases, information on the mechanisms of targeted genome modification, as well as hitherto reported applications of Cas endonuclease technology in barley and wheat that are the agronomically most important members of the temperate cereals. Finally, current trends in the further development of this technology and some ensuing future opportunities for research and biotechnological application are presented.
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Affiliation(s)
- Iris Koeppel
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466 Seeland, Germany.
| | - Christian Hertig
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466 Seeland, Germany.
| | - Robert Hoffie
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466 Seeland, Germany.
| | - Jochen Kumlehn
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466 Seeland, Germany.
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Fernandes JB, Wlodzimierz P, Henderson IR. Meiotic recombination within plant centromeres. CURRENT OPINION IN PLANT BIOLOGY 2019; 48:26-35. [PMID: 30954771 DOI: 10.1016/j.pbi.2019.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/21/2019] [Accepted: 02/28/2019] [Indexed: 05/18/2023]
Abstract
Meiosis is a conserved eukaryotic cell division that increases genetic diversity in sexual populations. During meiosis homologous chromosomes pair and undergo recombination that can result in reciprocal genetic exchange, termed crossover. The frequency of crossover is highly variable along chromosomes, with hot spots and cold spots. For example, the centromeres that contain the kinetochore, which attach chromosomes to the microtubular spindle, are crossover cold spots. Plant centromeres typically consist of large tandemly repeated arrays of satellite sequences and retrotransposons, a subset of which assemble CENH3-variant nucleosomes, which bind to kinetochore proteins. Although crossovers are suppressed in centromeres, there is abundant evidence for gene conversion and homologous recombination between repeats, which plays a role in satellite array change. We review the evidence for recombination within plant centromeres and the implications for satellite sequence evolution. We speculate on the genetic and epigenetic features of centromeres that may influence meiotic recombination in these regions. We also highlight unresolved questions relating to centromere function and sequence change and how the advent of new technologies promises to provide insights.
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Affiliation(s)
- Joiselle B Fernandes
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Piotr Wlodzimierz
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom.
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18
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Abstract
Genome engineering involves methods of genetic modification of cells at predefined genomic sites. Here, we used transcription activator-like effector nucleases (TALENs) for the site-directed mutagenesis in barley. Target gene-specific TALEN-encoding expression units were designed and delivered to totipotent cells of either cultivated embryogenic pollen or immature embryos. The analysis of resulting transgenic plants revealed that the described approach allows for the generation of site-specific, heritable mutations at reasonable efficiency.
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Affiliation(s)
- Goetz Hensel
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany
| | - Jochen Kumlehn
- Plant Reproductive Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany.
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19
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Schmidt C, Pacher M, Puchta H. DNA Break Repair in Plants and Its Application for Genome Engineering. Methods Mol Biol 2019; 1864:237-266. [PMID: 30415341 DOI: 10.1007/978-1-4939-8778-8_17] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Genome engineering is a biotechnological approach to precisely modify the genetic code of a given organism in order to change the context of an existing sequence or to create new genetic resources, e.g., for obtaining improved traits or performance. Efficient targeted genome alterations are mainly based on the induction of DNA double-strand breaks (DSBs) or adjacent single-strand breaks (SSBs). Naturally, all organisms continuously have to deal with DNA-damaging factors challenging the genetic integrity, and therefore a wide range of DNA repair mechanisms have evolved. A profound understanding of the different repair pathways is a prerequisite to control and enhance targeted gene modifications. DSB repair can take place by nonhomologous end joining (NHEJ) or homology-dependent repair (HDR). As the main outcome of NHEJ-mediated repair is accompanied by small insertions and deletions, it is applicable to specifically knock out genes or to rearrange linkage groups or whole chromosomes. The basic requirement for HDR is the presence of a homologous template; thus this process can be exploited for targeted integration of ectopic sequences into the plant genome. The development of different types of artificial site-specific nucleases allows for targeted DSB induction in the plant genome. Such synthetic nucleases have been used for both qualitatively studying DSB repair in vivo with respect to mechanistic differences and quantitatively in order to determine the role of key factors for NHEJ and HR, respectively. The conclusions drawn from these studies allow for a better understanding of genome evolution and help identifying synergistic or antagonistic genetic interactions while supporting biotechnological applications for transiently modifying the plant DNA repair machinery in favor of targeted genome engineering.
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Affiliation(s)
- Carla Schmidt
- Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Michael Pacher
- Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Holger Puchta
- Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany.
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20
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Shams I, Raskina O. Intraspecific and intraorganismal copy number dynamics of retrotransposons and tandem repeat in Aegilops speltoides Tausch (Poaceae, Triticeae). PROTOPLASMA 2018; 255:1023-1038. [PMID: 29374788 DOI: 10.1007/s00709-018-1212-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/14/2018] [Indexed: 06/07/2023]
Abstract
Transposable elements (TE) and tandem repeats (TR) compose the largest fraction of the plant genome. The abundance and repatterning of repetitive DNA underlie intrapopulation polymorphisms and intraspecific diversification; however, the dynamics of repetitive elements in ontogenesis is not fully understood. Here, we addressed the genotype-specific and tissue-specific abundances and dynamics of the Ty1-copia, Ty3-gypsy, and LINE retrotransposons and species-specific Spelt1 tandem repeat in wild diploid goatgrass, Aegilops speltoides Tausch. Copy numbers of TEs and TR were estimated by real-time quantitative PCR in vegetative and generative tissues in original plants from contrasting allopatric populations and artificial intraspecific hybrids. The results showed that between leaves and somatic spike tissues as well as in progressive microsporogenesis of individual genotypes, the copy numbers of three TEs correlatively oscillated between 2- to 4-fold and the TR copy numbers fluctuated by 18- to 440-fold. Inter-individual and intraorganismal TEs and TR copy number dynamics demonstrate large-scale parallelism with extensive chromosomal rearrangements that were detected using fluorescent in situ hybridization in parental and hybrid genotypes. The data obtained indicate that tissue-specific differences in the abundance and pattern of repetitive sequences emerge during cell proliferation and differentiation in ontogenesis and reflect the reorganization of individual genomes in changing environments, especially in small peripheral population(s) under the influence of rapid climatic changes.
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Affiliation(s)
- Imad Shams
- Institute of Evolution and Department of Evolutionary and Environmental Biology, University of Haifa, Aba-Hushi Avenue 199, 3498838, Haifa, Mount Carmel, Israel
| | - Olga Raskina
- Institute of Evolution and Department of Evolutionary and Environmental Biology, University of Haifa, Aba-Hushi Avenue 199, 3498838, Haifa, Mount Carmel, Israel.
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21
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What is behind “centromere repositioning”? Chromosoma 2018; 127:229-234. [DOI: 10.1007/s00412-018-0672-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/17/2018] [Accepted: 04/19/2018] [Indexed: 12/11/2022]
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Vu GTH, Cao HX, Fauser F, Reiss B, Puchta H, Schubert I. Endogenous sequence patterns predispose the repair modes of CRISPR/Cas9-induced DNA double-stranded breaks in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:57-67. [PMID: 28696528 DOI: 10.1111/tpj.13634] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 07/03/2017] [Accepted: 07/07/2017] [Indexed: 05/20/2023]
Abstract
The possibility to predict the outcome of targeted DNA double-stranded break (DSB) repair would be desirable for genome editing. Furthermore the consequences of mis-repair of potentially cell-lethal DSBs and the underlying pathways are not yet fully understood. Here we study the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-induced mutation spectra at three selected endogenous loci in Arabidopsis thaliana by deep sequencing of long amplicon libraries. Notably, we found sequence-dependent genomic features that affected the DNA repair outcome. Deletions of 1-bp to <1000-bp size and/or very short insertions, deletions >1 kbp (all due to NHEJ) and deletions combined with insertions between 5-bp to >100 bp [caused by a synthesis-dependent strand annealing (SDSA)-like mechanism] occurred most frequently at all three loci. The appearance of single-stranded annealing events depends on the presence and distance between repeats flanking the DSB. The frequency and size of insertions is increased if a sequence with high similarity to the target site was available in cis. Most deletions were linked to pre-existing microhomology. Deletion and/or insertion mutations were blunt-end ligated or via de novo generated microhomology. While most mutation types and, to some degree, their predictability are comparable with animal systems, the broad range of deletion mutations seems to be a peculiar feature of the plant A. thaliana.
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Affiliation(s)
- Giang T H Vu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D 06466, Gatersleben, Stadt Seeland, Germany
| | - Hieu X Cao
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D 06466, Gatersleben, Stadt Seeland, Germany
| | - Friedrich Fauser
- Botanical Institute II, Karlsruhe Institute of Technology, POB 6980, Karlsruhe, 76049, Germany
| | - Bernd Reiss
- Max Planck Institute for Plant Breeding Research, 50829, Köln, Germany
| | - Holger Puchta
- Botanical Institute II, Karlsruhe Institute of Technology, POB 6980, Karlsruhe, 76049, Germany
| | - Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D 06466, Gatersleben, Stadt Seeland, Germany
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23
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Vu GTH, Cao HX, Reiss B, Schubert I. Deletion-bias in DNA double-strand break repair differentially contributes to plant genome shrinkage. THE NEW PHYTOLOGIST 2017; 214:1712-1721. [PMID: 28245065 DOI: 10.1111/nph.14490] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/22/2017] [Indexed: 06/06/2023]
Abstract
In order to prevent genome instability, cells need to be protected by a number of repair mechanisms, including DNA double-strand break (DSB) repair. The extent to which DSB repair, biased towards deletions or insertions, contributes to evolutionary diversification of genome size is still under debate. We analyzed mutation spectra in Arabidopsis thaliana and in barley (Hordeum vulgare) by PacBio sequencing of three DSB-targeted loci each, uncovering repair via gene conversion, single strand annealing (SSA) or nonhomologous end-joining (NHEJ). Furthermore, phylogenomic comparisons between A. thaliana and two related species were used to detect naturally occurring deletions during Arabidopsis evolution. Arabidopsis thaliana revealed significantly more and larger deletions after DSB repair than barley, and barley displayed more and larger insertions. Arabidopsis displayed a clear net loss of DNA after DSB repair, mainly via SSA and NHEJ. Barley revealed a very weak net loss of DNA, apparently due to less active break-end resection and easier copying of template sequences into breaks. Comparative phylogenomics revealed several footprints of SSA in the A. thaliana genome. Quantitative assessment of DNA gain and loss through DSB repair processes suggests deletion-biased DSB repair causing ongoing genome shrinking in A. thaliana, whereas genome size in barley remains nearly constant.
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Affiliation(s)
- Giang T H Vu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466, Gatersleben, Germany
| | - Hieu X Cao
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466, Gatersleben, Germany
| | - Bernd Reiss
- Max Planck Institute for Plant Breeding Research, 50829, Köln, Germany
| | - Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466, Gatersleben, Germany
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24
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Targeted recombination between homologous chromosomes for precise breeding in tomato. Nat Commun 2017; 8:15605. [PMID: 28548094 PMCID: PMC5458649 DOI: 10.1038/ncomms15605] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/05/2017] [Indexed: 01/10/2023] Open
Abstract
Homologous recombination (HR) between parental chromosomes occurs stochastically. Here, we report on targeted recombination between homologous chromosomes upon somatic induction of DNA double-strand breaks (DSBs) via CRISPR-Cas9. We demonstrate this via a visual and molecular assay whereby DSB induction between two alleles carrying different mutations in the PHYTOENE SYNTHASE (PSY1) gene results in yellow fruits with wild type red sectors forming via HR-mediated DSB repair. We also show that in heterozygote plants containing one psy1 allele immune and one sensitive to CRISPR, repair of the broken allele using the unbroken allele sequence template is a common outcome. In another assay, we show evidence of a somatically induced DSB in a cross between a psy1 edible tomato mutant and wild type Solanum pimpinellifolium, targeting only the S. pimpinellifolium allele. This enables characterization of germinally transmitted targeted somatic HR events, demonstrating that somatically induced DSBs can be exploited for precise breeding of crops. Targeted homologous recombination between parental chromosomes could facilitate precision breeding of crop plants. Here, Filler Hayut et al. show that CRISPR-Cas9 can be used to induce DNA double strand breaks in somatic tissue and achieve targeted recombination between homologs at an endogenous locus in tomato.
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Horvath M, Steinbiss HH, Reiss B. Gene Targeting Without DSB Induction Is Inefficient in Barley. FRONTIERS IN PLANT SCIENCE 2017; 7:1973. [PMID: 28105032 PMCID: PMC5214849 DOI: 10.3389/fpls.2016.01973] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/13/2016] [Indexed: 05/29/2023]
Abstract
Double strand-break (DSB) induction allowed efficient gene targeting in barley (Hordeum vulgare), but little is known about efficiencies in its absence. To obtain such data, an assay system based on the acetolactate synthase (ALS) gene was established, a target gene which had been used previously in rice and Arabidopsis thaliana. Expression of recombinases RAD51 and RAD54 had been shown to improve gene targeting in A. thaliana and positive-negative (P-N) selection allows the routine production of targeted mutants without DSB induction in rice. We implemented these approaches in barley and analysed gene targeting with the ALS gene in wild type and RAD51 and RAD54 transgenic lines. In addition, P-N selection was tested. In contrast to the high gene targeting efficiencies obtained in the absence of DSB induction in A. thaliana or rice, not one single gene targeting event was obtained in barley. These data suggest that gene targeting efficiencies are very low in barley and can substantially differ between different plants, even at the same target locus. They also suggest that the amount of labour and time would become unreasonably high to use these methods as a tool in routine applications. This is particularly true since DSB induction offers efficient alternatives. Barley, unlike rice and A. thaliana has a large, complex genome, suggesting that genome size or complexity could be the reason for the low efficiencies. We discuss to what extent transformation methods, genome size or genome complexity could contribute to the striking differences in the gene targeting efficiencies between barley, rice and A. thaliana.
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Affiliation(s)
| | | | - Bernd Reiss
- Plant DNA Recombination Group, Max Planck Institute for Plant Breeding ResearchCologne, Germany
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26
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Shen H, Strunks GD, Klemann BJPM, Hooykaas PJJ, de Pater S. CRISPR/Cas9-Induced Double-Strand Break Repair in Arabidopsis Nonhomologous End-Joining Mutants. G3 (BETHESDA, MD.) 2017; 7:193-202. [PMID: 27866150 PMCID: PMC5217109 DOI: 10.1534/g3.116.035204] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 11/03/2016] [Indexed: 01/31/2023]
Abstract
Double-strand breaks (DSBs) are one of the most harmful DNA lesions. Cells utilize two main pathways for DSB repair: homologous recombination (HR) and nonhomologous end-joining (NHEJ). NHEJ can be subdivided into the KU-dependent classical NHEJ (c-NHEJ) and the more error-prone KU-independent backup-NHEJ (b-NHEJ) pathways, involving the poly (ADP-ribose) polymerases (PARPs). However, in the absence of these factors, cells still seem able to adequately maintain genome integrity, suggesting the presence of other b-NHEJ repair factors or pathways independent from KU and PARPs. The outcome of DSB repair by NHEJ pathways can be investigated by using artificial sequence-specific nucleases such as CRISPR/Cas9 to induce DSBs at a target of interest. Here, we used CRISPR/Cas9 for DSB induction at the Arabidopsis cruciferin 3 (CRU3) and protoporphyrinogen oxidase (PPO) genes. DSB repair outcomes via NHEJ were analyzed using footprint analysis in wild-type plants and plants deficient in key factors of c-NHEJ (ku80), b-NHEJ (parp1 parp2), or both (ku80 parp1 parp2). We found that larger deletions of >20 bp predominated after DSB repair in ku80 and ku80 parp1 parp2 mutants, corroborating with a role of KU in preventing DSB end resection. Deletion lengths did not significantly differ between ku80 and ku80 parp1 parp2 mutants, suggesting that a KU- and PARP-independent b-NHEJ mechanism becomes active in these mutants. Furthermore, microhomologies and templated insertions were observed at the repair junctions in the wild type and all mutants. Since these characteristics are hallmarks of polymerase θ-mediated DSB repair, we suggest a possible role for this recently discovered polymerase in DSB repair in plants.
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Affiliation(s)
- Hexi Shen
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, 2333 BE, The Netherlands
| | - Gary D Strunks
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, 2333 BE, The Netherlands
| | - Bart J P M Klemann
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, 2333 BE, The Netherlands
| | - Paul J J Hooykaas
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, 2333 BE, The Netherlands
| | - Sylvia de Pater
- Department of Molecular and Developmental Genetics, Institute of Biology, Leiden University, 2333 BE, The Netherlands
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27
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Schubert V. Super-resolution Microscopy - Applications in Plant Cell Research. FRONTIERS IN PLANT SCIENCE 2017; 8:531. [PMID: 28450874 PMCID: PMC5390026 DOI: 10.3389/fpls.2017.00531] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/24/2017] [Indexed: 05/10/2023]
Abstract
Most of the present knowledge about cell organization and function is based on molecular and genetic methods as well as cytological investigations. While electron microscopy allows identifying cell substructures until a resolution of ∼1 nm, the resolution of fluorescence microscopy is restricted to ∼200 nm due to the diffraction limit of light. However, the advantage of this technique is the possibility to identify and co-localize specifically labeled structures and molecules. The recently developed super-resolution microscopy techniques, such as Structured Illumination Microscopy, Photoactivated Localization Microscopy, Stochastic Optical Reconstruction Microscopy, and Stimulated Emission Depletion microscopy allow analyzing structures and molecules beyond the diffraction limit of light. Recently, there is an increasing application of these techniques in cell biology. This review evaluates and summarizes especially the data achieved until now in analyzing the organization and function of plant cells, chromosomes and interphase nuclei using super-resolution techniques.
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Cao HX, Wang W, Le HTT, Vu GTH. The Power of CRISPR-Cas9-Induced Genome Editing to Speed Up Plant Breeding. Int J Genomics 2016; 2016:5078796. [PMID: 28097123 PMCID: PMC5206445 DOI: 10.1155/2016/5078796] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/17/2016] [Accepted: 11/01/2016] [Indexed: 12/26/2022] Open
Abstract
Genome editing with engineered nucleases enabling site-directed sequence modifications bears a great potential for advanced plant breeding and crop protection. Remarkably, the RNA-guided endonuclease technology (RGEN) based on the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) is an extremely powerful and easy tool that revolutionizes both basic research and plant breeding. Here, we review the major technical advances and recent applications of the CRISPR-Cas9 system for manipulation of model and crop plant genomes. We also discuss the future prospects of this technology in molecular plant breeding.
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Affiliation(s)
- Hieu X. Cao
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, Gatersleben, 06466 Stadt Seeland, Germany
| | - Wenqin Wang
- School of Agriculture and Biology, Shanghai Jiaotong University, 800 Dong Chuan Road, Shanghai 200240, China
| | - Hien T. T. Le
- Institute of Genome Research, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Vietnam
| | - Giang T. H. Vu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, Gatersleben, 06466 Stadt Seeland, Germany
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Analysis of Repair Mechanisms following an Induced Double-Strand Break Uncovers Recessive Deleterious Alleles in the Candida albicans Diploid Genome. mBio 2016; 7:mBio.01109-16. [PMID: 27729506 PMCID: PMC5061868 DOI: 10.1128/mbio.01109-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The diploid genome of the yeast Candida albicans is highly plastic, exhibiting frequent loss-of-heterozygosity (LOH) events. To provide a deeper understanding of the mechanisms leading to LOH, we investigated the repair of a unique DNA double-strand break (DSB) in the laboratory C. albicans SC5314 strain using the I-SceI meganuclease. Upon I-SceI induction, we detected a strong increase in the frequency of LOH events at an I-SceI target locus positioned on chromosome 4 (Chr4), including events spreading from this locus to the proximal telomere. Characterization of the repair events by single nucleotide polymorphism (SNP) typing and whole-genome sequencing revealed a predominance of gene conversions, but we also observed mitotic crossover or break-induced replication events, as well as combinations of independent events. Importantly, progeny that had undergone homozygosis of part or all of Chr4 haplotype B (Chr4B) were inviable. Mining of genome sequencing data for 155 C. albicans isolates allowed the identification of a recessive lethal allele in the GPI16 gene on Chr4B unique to C. albicans strain SC5314 which is responsible for this inviability. Additional recessive lethal or deleterious alleles were identified in the genomes of strain SC5314 and two clinical isolates. Our results demonstrate that recessive lethal alleles in the genomes of C. albicans isolates prevent the occurrence of specific extended LOH events. While these and other recessive lethal and deleterious alleles are likely to accumulate in C. albicans due to clonal reproduction, their occurrence may in turn promote the maintenance of corresponding nondeleterious alleles and, consequently, heterozygosity in the C. albicans species. IMPORTANCE Recessive lethal alleles impose significant constraints on the biology of diploid organisms. Using a combination of an I-SceI meganuclease-mediated DNA DSB, a fluorescence-activated cell sorter (FACS)-optimized reporter of LOH, and a compendium of 155 genome sequences, we were able to unmask and identify recessive lethal and deleterious alleles in isolates of Candida albicans, a diploid yeast and the major fungal pathogen of humans. Accumulation of recessive deleterious mutations upon clonal reproduction of C. albicans could contribute to the maintenance of heterozygosity despite the high frequency of LOH events in this species.
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Schubert I, Vu GTH. Genome Stability and Evolution: Attempting a Holistic View. TRENDS IN PLANT SCIENCE 2016; 21:749-757. [PMID: 27427334 DOI: 10.1016/j.tplants.2016.06.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/06/2016] [Accepted: 06/15/2016] [Indexed: 05/02/2023]
Abstract
The reason why the DNA content, chromosome number and shape, and gene content of eukaryotic genomes vary independently remains a matter of speculation. The same is true for the questions of whether there is a general tendency for increase or decrease of genome size and chromosome number and whether genome size and/or chromosome number have an adaptive value and, if so, what this value is. Here we assume that three strategies of genome evolution (shrinkage, expansion, and equilibrium) have developed to find the optimal balance between genomic stability and plasticity. We suggest various modes of DNA double-strand break (DSB) repair in combination with whole-genome duplication (WGD) and dysploid chromosome number alteration to explain the different strategies of genome size and karyotype evolution.
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Affiliation(s)
- Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D 06466 Gatersleben, Stadt Seeland, Germany.
| | - Giang T H Vu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D 06466 Gatersleben, Stadt Seeland, Germany
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Watanabe K, Breier U, Hensel G, Kumlehn J, Schubert I, Reiss B. Stable gene replacement in barley by targeted double-strand break induction. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:1433-45. [PMID: 26712824 PMCID: PMC4762383 DOI: 10.1093/jxb/erv537] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Gene targeting is becoming an important tool for precision genome engineering in plants. During gene replacement, a variant of gene targeting, transformed DNA integrates into the genome by homologous recombination (HR) to replace resident sequences. We have analysed gene targeting in barley (Hordeum vulgare) using a model system based on double-strand break (DSB) induction by the meganuclease I-SceI and a transgenic, artificial target locus. In the plants we obtained, the donor construct was inserted at the target locus by homology-directed DNA integration in at least two transformants obtained in a single experiment and was stably inherited as a single Mendelian trait. Both events were produced by one-sided integration. Our data suggest that gene replacement can be achieved in barley with a frequency suitable for routine application. The use of a codon-optimized nuclease and co-transfer of the nuclease gene together with the donor construct are probably the components important for efficient gene targeting. Such an approach, employing the recently developed synthetic nucleases/nickases that allow DSB induction at almost any sequence of a genome of interest, sets the stage for precision genome engineering as a routine tool even for important crops such as barley.
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Affiliation(s)
- Koichi Watanabe
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Stadt Seeland, Germany
| | - Ulrike Breier
- Max-Planck-Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, D-50829 Cologne, Germany
| | - Götz Hensel
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Stadt Seeland, Germany
| | - Jochen Kumlehn
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Stadt Seeland, Germany
| | - Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Stadt Seeland, Germany Faculty of Science and Central European Institute of Technology, Masaryk University, 61137 Brno, Czech Republic
| | - Bernd Reiss
- Max-Planck-Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, D-50829 Cologne, Germany
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Nishizawa-Yokoi A, Cermak T, Hoshino T, Sugimoto K, Saika H, Mori A, Osakabe K, Hamada M, Katayose Y, Starker C, Voytas DF, Toki S. A Defect in DNA Ligase4 Enhances the Frequency of TALEN-Mediated Targeted Mutagenesis in Rice. PLANT PHYSIOLOGY 2016; 170:653-66. [PMID: 26668331 PMCID: PMC4734567 DOI: 10.1104/pp.15.01542] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 12/10/2015] [Indexed: 05/02/2023]
Abstract
We have established methods for site-directed mutagenesis via transcription activator-like effector nucleases (TALENs) in the endogenous rice (Oryza sativa) waxy gene and demonstrated stable inheritance of TALEN-induced somatic mutations to the progeny. To analyze the role of classical nonhomologous end joining (cNHEJ) and alternative nonhomologous end joining (altNHEJ) pathways in TALEN-induced mutagenesis in plant cells, we investigated whether a lack of DNA Ligase4 (Lig4) affects the kinetics of TALEN-induced double-strand break repair in rice cells. Deep-sequencing analysis revealed that the frequency of all types of mutations, namely deletion, insertion, combination of insertion with deletion, and substitution, in lig4 null mutant calli was higher than that in a lig4 heterozygous mutant or the wild type. In addition, the ratio of large deletions (greater than 10 bp) and deletions repaired by microhomology-mediated end joining (MMEJ) to total deletion mutations in lig4 null mutant calli was higher than that in the lig4 heterozygous mutant or wild type. Furthermore, almost all insertions (2 bp or greater) were shown to be processed via copy and paste of one or more regions around the TALENs cleavage site and rejoined via MMEJ regardless of genetic background. Taken together, our findings indicate that the dysfunction of cNHEJ leads to a shift in the repair pathway from cNHEJ to altNHEJ or synthesis-dependent strand annealing.
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Affiliation(s)
- Ayako Nishizawa-Yokoi
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Tomas Cermak
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Tomoki Hoshino
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Kazuhiko Sugimoto
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Hiroaki Saika
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Akiko Mori
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Keishi Osakabe
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Masao Hamada
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Yuichi Katayose
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Colby Starker
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Daniel F Voytas
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
| | - Seiichi Toki
- Plant Genome Engineering Research Unit (A.N.-Y., H.S., A.M., S.T.), Rice Applied Genomics Research Unit (T.H., K.S.), and Advanced Genomics Laboratory (M.H., Y.K.), National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan;Department of Genetics, Cell Biology, and Development and Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (T.C., C.S., D.F.V.);Center for Collaboration among Agriculture, Industry, and Commerce, University of Tokushima, Tokushima 770-8503, Japan (K.O.); andKihara Institute for Biological Research, Yokohama City University, Yokohama 244-0813, Japan (S.T.)
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Vu GTH, Schmutzer T, Bull F, Cao HX, Fuchs J, Tran TD, Jovtchev G, Pistrick K, Stein N, Pecinka A, Neumann P, Novak P, Macas J, Dear PH, Blattner FR, Scholz U, Schubert I. Comparative Genome Analysis Reveals Divergent Genome Size Evolution in a Carnivorous Plant Genus. THE PLANT GENOME 2015; 8:eplantgenome2015.04.0021. [PMID: 33228273 DOI: 10.3835/plantgenome2015.04.0021] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/19/2015] [Indexed: 06/11/2023]
Abstract
The C-value paradox remains incompletely resolved after >40 yr and is exemplified by 2,350-fold variation in genome sizes of flowering plants. The carnivorous Lentibulariaceae genus Genlisea, displaying a 25-fold range of genome sizes, is a promising subject to study mechanisms and consequences of evolutionary genome size variation. Applying genomic, phylogenetic, and cytogenetic approaches, we uncovered bidirectional genome size evolution within the genus Genlisea. The Genlisea nigrocaulis Steyerm. genome (86 Mbp) has probably shrunk by retroelement silencing and deletion-biased double-strand break (DSB) repair, from an ancestral size of 400 to 800 Mbp to become one of the smallest among flowering plants. The G. hispidula Stapf genome has expanded by whole-genome duplication (WGD) and retrotransposition to 1550 Mbp. Genlisea hispidula became allotetraploid after the split from the G. nigrocaulis clade ∼29 Ma. Genlisea pygmaea A. St.-Hil. (179 Mbp), a close relative of G. nigrocaulis, proved to be a recent (auto)tetraploid. Our analyses suggest a common ancestor of the genus Genlisea with an intermediate 1C value (400-800 Mbp) and subsequent rapid genome size evolution in opposite directions. Many abundant repeats of the larger genome are absent in the smaller, casting doubt on their functionality for the organism, while recurrent WGD seems to safeguard against the loss of essential elements in the face of genome shrinkage. We cannot identify any consistent differences in habitat or life strategy that correlate with genome size changes, raising the possibility that these changes may be selectively neutral.
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Affiliation(s)
- Giang T H Vu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- Max Planck Institute for Plant Breeding Research (MPIPZ), Carl-von-Linné-Weg 10, 50829, Köln, Germany
| | - Thomas Schmutzer
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Fabian Bull
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Hieu X Cao
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Jörg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Trung D Tran
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Gabriele Jovtchev
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- Institute for Biodiversity and Ecosystem Research, 2 Yurii Gagarin Street, Sofia, 1113, Bulgaria
| | - Klaus Pistrick
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Nils Stein
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Ales Pecinka
- Max Planck Institute for Plant Breeding Research (MPIPZ), Carl-von-Linné-Weg 10, 50829, Köln, Germany
| | - Pavel Neumann
- Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Plant Molecular Biology, 370 05, Cˇeske Budejovicé, Czech Republic
| | - Petr Novak
- Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Plant Molecular Biology, 370 05, Cˇeske Budejovicé, Czech Republic
| | - Jiri Macas
- Biology Centre of the Academy of Sciences of the Czech Republic, Institute of Plant Molecular Biology, 370 05, Cˇeske Budejovicé, Czech Republic
| | - Paul H Dear
- MRC Lab. of Molecular Biology, Francis Crick Ave., Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Frank R Blattner
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany
| | - Uwe Scholz
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
| | - Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany
- Faculty of Science and Central European Institute of Technology, Masaryk Univ., 61137, Brno, Czech Republic
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Nandy S, Zhao S, Pathak BP, Manoharan M, Srivastava V. Gene stacking in plant cell using recombinases for gene integration and nucleases for marker gene deletion. BMC Biotechnol 2015; 15:93. [PMID: 26452472 PMCID: PMC4600305 DOI: 10.1186/s12896-015-0212-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/01/2015] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Practical approaches for multigene transformation and gene stacking are extremely important for engineering complex traits and adding new traits in transgenic crops. Trait deployment by gene stacking would greatly simplify downstream plant breeding and trait introgression into cultivars. Gene stacking into pre-determined genomic sites depends on mechanisms of targeted DNA integration and recycling of selectable marker genes. Targeted integrations into chromosomal breaks, created by nucleases, require large transformation efforts. Recombinases such as Cre-lox, on the other hand, efficiently drive site-specific integrations in plants. However, the reversibility of Cre-lox recombination, due to the incorporation of two cis-positioned lox sites, presents a major bottleneck in its application in gene stacking. Here, we describe a strategy of resolving this bottleneck through excision of one of the cis-positioned lox, embedded in the marker gene, by nuclease activity. METHODS All transgenic lines were developed by particle bombardment of rice callus with plasmid constructs. Standard molecular approach was used for building the constructs. Transgene loci were analyzed by PCR, Southern hybridization, and DNA sequencing. RESULTS We developed a highly efficient gene stacking method by utilizing powerful recombinases such as Cre-lox and FLP-FRT, for site-specific gene integrations, and nucleases for marker gene excisions. We generated Cre-mediated site-specific integration locus in rice and showed excision of marker gene by I-SceI at ~20 % efficiency, seamlessly connecting genes in the locus. Next, we showed ZFN could be used for marker excision, and the locus can be targeted again by recombinases. Hence, we extended the power of recombinases to gene stacking application in plants. Finally, we show that heat-inducible I-SceI is also suitable for marker excision, and therefore could serve as an important tool in streamlining this gene stacking platform. CONCLUSIONS A practical approach for gene stacking in plant cell was developed that allows targeted gene insertions through rounds of transformation, a method needed for introducing new traits into transgenic lines for their rapid deployment in the field. By using Cre-lox, a powerful site-specific recombination system, this method greatly improves gene stacking efficiency, and through the application of nucleases develops marker-free, seamless stack of genes at pre-determined chromosomal sites.
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Affiliation(s)
- Soumen Nandy
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Shan Zhao
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Bhuvan P Pathak
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Muthusamy Manoharan
- Department of Agriculture, 144 Woodard Hall, University of Arkansas at Pine Bluff, Pine Bluff, AR, 71601, USA.
| | - Vibha Srivastava
- Department of Crop, Soil & Environmental Science, 115 Plant Science Building, University of Arkansas, Fayetteville, AR, 72701, USA.
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Targeted Modification of Gene Function Exploiting Homology-Directed Repair of TALEN-Mediated Double-Strand Breaks in Barley. G3-GENES GENOMES GENETICS 2015; 5:1857-63. [PMID: 26153077 PMCID: PMC4555222 DOI: 10.1534/g3.115.018762] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Transcription activator-like effector nucleases open up new opportunities for targeted mutagenesis in eukaryotic genomes. Similar to zinc-finger nucleases, sequence-specific DNA-binding domains can be fused with effector domains like the nucleolytically active part of FokI to induce double-strand breaks and thereby modify the host genome on a predefined target site via nonhomologous end joining. More sophisticated applications of programmable endonucleases involve the use of a DNA repair template facilitating homology-directed repair (HDR) so as to create predefined rather than random DNA sequence modifications. The aim of this study was to demonstrate the feasibility of editing the barley genome by precisely modifying a defined target DNA sequence resulting in a predicted alteration of gene function. We used gfp-specific transcription activator-like effector nucleases along with a repair template that, via HDR, facilitates conversion of gfp into yfp, which is associated with a single amino acid exchange in the gene product. As a result of co-bombardment of leaf epidermis, we detected yellow fluorescent protein accumulation in about three of 100 mutated cells. The creation of a functional yfp gene via HDR was unambiguously confirmed by sequencing of the respective genomic site. In addition to the allele conversion accomplished in planta, a readily screenable marker system is introduced that might be useful for optimization approaches in the field of genome editing.
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Dvořáčková M, Fojtová M, Fajkus J. Chromatin dynamics of plant telomeres and ribosomal genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:18-37. [PMID: 25752316 DOI: 10.1111/tpj.12822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 05/03/2023]
Abstract
Telomeres and genes encoding 45S ribosomal RNA (rDNA) are frequently located adjacent to each other on eukaryotic chromosomes. Although their primary roles are different, they show striking similarities with respect to their features and additional functions. Both genome domains have remarkably dynamic chromatin structures. Both are hypersensitive to dysfunctional histone chaperones, responding at the genomic and epigenomic levels. Both generate non-coding transcripts that, in addition to their epigenetic roles, may induce gross chromosomal rearrangements. Both give rise to chromosomal fragile sites, as their replication is intrinsically problematic. However, at the same time, both are essential for maintenance of genomic stability and integrity. Here we discuss the structural and functional inter-connectivity of telomeres and rDNA, with a focus on recent results obtained in plants.
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Affiliation(s)
- Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Kamenice 5, 62500, Brno, Czech Republic
- Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265, Brno, Czech Republic
| | - Miloslava Fojtová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Kamenice 5, 62500, Brno, Czech Republic
- Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265, Brno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Kamenice 5, 62500, Brno, Czech Republic
- Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265, Brno, Czech Republic
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Xu RF, Li H, Qin RY, Li J, Qiu CH, Yang YC, Ma H, Li L, Wei PC, Yang JB. Generation of inheritable and "transgene clean" targeted genome-modified rice in later generations using the CRISPR/Cas9 system. Sci Rep 2015; 5:11491. [PMID: 26089199 PMCID: PMC5155577 DOI: 10.1038/srep11491] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/26/2015] [Indexed: 12/23/2022] Open
Abstract
The CRISPR/Cas9 system is becoming an important genome editing tool for crop breeding. Although it has been demonstrated that target mutations can be transmitted to the next generation, their inheritance pattern has not yet been fully elucidated. Here, we describe the CRISPR/Cas9-mediated genome editing of four different rice genes with the help of online target-design tools. High-frequency mutagenesis and a large percentage of putative biallelic mutations were observed in T0 generations. Nonetheless, our results also indicate that the progeny genotypes of biallelic T0 lines are frequently difficult to predict and that the transmission of mutations largely does not conform to classical genetic laws, which suggests that the mutations in T0 transgenic rice are mainly somatic mutations. Next, we followed the inheritance pattern of T1 plants. Regardless of the presence of the CRISPR/Cas9 transgene, the mutations in T1 lines were stably transmitted to later generations, indicating a standard germline transmission pattern. Off-target effects were also evaluated, and our results indicate that with careful target selection, off-target mutations are rare in CRISPR/Cas9-mediated rice gene editing. Taken together, our results indicate the promising production of inheritable and "transgene clean" targeted genome-modified rice in the T1 generation using the CRISPR/Cas9 system.
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Affiliation(s)
- Rong-Fang Xu
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Hao Li
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Rui-Ying Qin
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Juan Li
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Chun-Hong Qiu
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Ya-Chun Yang
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Hui Ma
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Li Li
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Peng-Cheng Wei
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
| | - Jian-Bo Yang
- Key Laboratory of Rice Genetic Breeding of Anhui Province, Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei, 230031, China
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Roffler S, Wicker T. Genome-wide comparison of Asian and African rice reveals high recent activity of DNA transposons. Mob DNA 2015; 6:8. [PMID: 25954322 PMCID: PMC4423477 DOI: 10.1186/s13100-015-0040-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/16/2015] [Indexed: 12/18/2022] Open
Abstract
Background DNA (Class II) transposons are ubiquitous in plant genomes. However, unlike for (Class I) retrotransposons, only little is known about their proliferation mechanisms, activity, and impact on genomes. Asian and African rice (Oryza sativa and O. glaberrima) diverged approximately 600,000 years ago. Their fully sequenced genomes therefore provide an excellent opportunity to study polymorphisms introduced from recent transposon activity. Results We manually analyzed 1,821 transposon related polymorphisms among which we identified 487 loci which clearly resulted from DNA transposon insertions and excisions. In total, we estimate about 4,000 (3.5% of all DNA transposons) to be polymorphic between the two species, indicating a high level of transposable element (TE) activity. The vast majority of the recently active elements are non-autonomous. Nevertheless, we identified multiple potentially functional autonomous elements. Furthermore, we quantified the impacts of insertions and excisions on the adjacent sequences. Transposon insertions were found to be generally precise, creating simple target site duplications. In contrast, excisions almost always go along with the deletion of flanking sequences and/or the insertion of foreign ‘filler’ segments. Some of the excision-triggered deletions ranged from hundreds to thousands of bp flanking the excision site. Furthermore, we found in some superfamilies unexpectedly low numbers of excisions. This suggests that some excisions might cause such large-scale rearrangements so that they cannot be detected anymore. Conclusions We conclude that the activity of DNA transposons (particularly the excision process) is a major evolutionary force driving the generation of genetic diversity. Electronic supplementary material The online version of this article (doi:10.1186/s13100-015-0040-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stefan Roffler
- Institute for Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Thomas Wicker
- Institute for Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
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Ladics GS, Bartholomaeus A, Bregitzer P, Doerrer NG, Gray A, Holzhauser T, Jordan M, Keese P, Kok E, Macdonald P, Parrott W, Privalle L, Raybould A, Rhee SY, Rice E, Romeis J, Vaughn J, Wal JM, Glenn K. Genetic basis and detection of unintended effects in genetically modified crop plants. Transgenic Res 2015; 24:587-603. [PMID: 25716164 PMCID: PMC4504983 DOI: 10.1007/s11248-015-9867-7] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 02/14/2015] [Indexed: 11/26/2022]
Abstract
In January 2014, an international meeting sponsored by the International Life Sciences Institute/Health and Environmental Sciences Institute and the Canadian Food Inspection Agency titled “Genetic Basis of Unintended Effects in Modified Plants” was held in Ottawa, Canada, bringing together over 75 scientists from academia, government, and the agro-biotech industry. The objectives of the meeting were to explore current knowledge and identify areas requiring further study on unintended effects in plants and to discuss how this information can inform and improve genetically modified (GM) crop risk assessments. The meeting featured presentations on the molecular basis of plant genome variability in general, unintended changes at the molecular and phenotypic levels, and the development and use of hypothesis-driven evaluations of unintended effects in assessing conventional and GM crops. The development and role of emerging “omics” technologies in the assessment of unintended effects was also discussed. Several themes recurred in a number of talks; for example, a common observation was that no system for genetic modification, including conventional methods of plant breeding, is without unintended effects. Another common observation was that “unintended” does not necessarily mean “harmful”. This paper summarizes key points from the information presented at the meeting to provide readers with current viewpoints on these topics.
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Affiliation(s)
- Gregory S. Ladics
- DuPont Pioneer Agricultural Biotechnology, DuPont Experimental Station, 200 Powder Mill Road, Wilmington, DE 19803 USA
| | - Andrew Bartholomaeus
- Therapeutics Research Centre, School of Medicine, Queensland University, Brisbane, QLD 4072 Australia
- Faculty of Health, School of Pharmacy, University of Canberra, Locked Bag 1, Canberra, ACT 2601 Australia
| | - Phil Bregitzer
- National Small Grains Germplasm Research Facility, US Department of Agriculture – Agricultural Research Service, 1691 S. 2700 W., Aberdeen, ID 83210 USA
| | - Nancy G. Doerrer
- ILSI Health and Environmental Sciences Institute, 1156 15th St., NW, Suite 200, Washington, DC 20005 USA
| | - Alan Gray
- Centre for Ecology and Hydrology, CEH Wallingford, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB UK
| | - Thomas Holzhauser
- Division of Allergology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, 63225 Langen, Germany
| | - Mark Jordan
- Cereal Research Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB R6M 1Y5 Canada
| | - Paul Keese
- Office of the Gene Technology Regulator, Australian Government, MDP54, GPO Box 9848, Canberra, ACT 2601 Australia
| | - Esther Kok
- RIKILT Wageningen UR, P.O. Box 230, 6700 AE Wageningen, The Netherlands
| | - Phil Macdonald
- Canadian Food Inspection Agency, 1400 Merivale Rd, Ottawa, ON K1A 0Y9 Canada
| | - Wayne Parrott
- Center for Applied Genetic Technologies, University of Georgia, 111 Riverbend Road, Athens, GA 30602 USA
| | - Laura Privalle
- Bayer CropScience, 407 Davis Drive, Morrisville, NC 27560 USA
| | - Alan Raybould
- Syngenta Ltd, Jealott’s Hill International Research Centre, Bracknell, RG42 6EY UK
- Present Address: Syngenta Crop Protection AG, Schwarzwaldallee 215, 4058 Basel, Switzerland
| | - Seung Yon Rhee
- Department of Plant Biology, Carnegie Institution for Science, 260 Panama St., Stanford, CA 94305 USA
| | - Elena Rice
- Monsanto Company, 700 Chesterfield Pkwy W., CC5A, Chesterfield, MO 63017 USA
| | - Jörg Romeis
- Agroscope, Institute for Sustainability Sciences ISS, Reckenholzstr. 191, 8046 Zurich, Switzerland
| | - Justin Vaughn
- University of Georgia, 111 Riverbend Road, Athens, GA 30602 USA
| | - Jean-Michel Wal
- Dept. SVS, AgroParisTech, 16 rue Claude Bernard, 75231 Paris, France
| | - Kevin Glenn
- Monsanto Company, 800 N. Lindbergh Blvd, U4NA, St. Louis, MO 63167 USA
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