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Kamoen L, Kralemann LEM, van Schendel R, van Tol N, Hooykaas PJJ, de Pater S, Tijsterman M. Genetic dissection of mutagenic repair and T-DNA capture at CRISPR-induced DNA breaks in Arabidopsis thaliana. PNAS NEXUS 2024; 3:pgae094. [PMID: 38463035 PMCID: PMC10923293 DOI: 10.1093/pnasnexus/pgae094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 02/13/2024] [Indexed: 03/12/2024]
Abstract
A practical and powerful approach for genome editing in plants is delivery of CRISPR reagents via Agrobacterium tumefaciens transformation. The double-strand break (DSB)-inducing enzyme is expressed from a transferred segment of bacterial DNA, the T-DNA, which upon transformation integrates at random locations into the host genome or is captured at the self-inflicted DSB site. To develop efficient strategies for precise genome editing, it is thus important to define the mechanisms that repair CRISPR-induced DSBs, as well as those that govern random and targeted integration of T-DNA. In this study, we present a detailed and comprehensive genetic analysis of Cas9-induced DSB repair and T-DNA capture in the model plant Arabidopsis thaliana. We found that classical nonhomologous end joining (cNHEJ) and polymerase theta-mediated end joining (TMEJ) are both, and in part redundantly, acting on CRISPR-induced DSBs to produce very different mutational outcomes. We used newly developed CISGUIDE technology to establish that 8% of mutant alleles have captured T-DNA at the induced break site. In addition, we find T-DNA shards within genomic DSB repair sites indicative of frequent temporary interactions during TMEJ. Analysis of thousands of plant genome-T-DNA junctions, followed up by genetic dissection, further reveals that TMEJ is responsible for attaching the 3' end of T-DNA to a CRISPR-induced DSB, while the 5' end can be attached via TMEJ as well as cNHEJ. By identifying the mechanisms that act to connect recombinogenic ends of DNA molecules at chromosomal breaks, and quantifying their contributions, our study supports the development of tailor-made strategies toward predictable engineering of crop plants.
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Affiliation(s)
- Lycka Kamoen
- Department of Plant Sciences, Institute of Biology Leiden, Leiden University, Leiden 2333 BE, The Netherlands
| | - Lejon E M Kralemann
- Department of Plant Sciences, Institute of Biology Leiden, Leiden University, Leiden 2333 BE, The Netherlands
- Department of Human Genetics, Leiden University Medical Center, Leiden 2300 RC, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden 2300 RC, The Netherlands
| | - Niels van Tol
- Department of Plant Sciences, Institute of Biology Leiden, Leiden University, Leiden 2333 BE, The Netherlands
- Department of Human Genetics, Leiden University Medical Center, Leiden 2300 RC, The Netherlands
| | - Paul J J Hooykaas
- Department of Plant Sciences, Institute of Biology Leiden, Leiden University, Leiden 2333 BE, The Netherlands
| | - Sylvia de Pater
- Department of Plant Sciences, Institute of Biology Leiden, Leiden University, Leiden 2333 BE, The Netherlands
| | - Marcel Tijsterman
- Department of Plant Sciences, Institute of Biology Leiden, Leiden University, Leiden 2333 BE, The Netherlands
- Department of Human Genetics, Leiden University Medical Center, Leiden 2300 RC, The Netherlands
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2
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Thomson G, Dickinson L, Jacob Y. Genomic consequences associated with Agrobacterium-mediated transformation of plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:342-363. [PMID: 37831618 PMCID: PMC10841553 DOI: 10.1111/tpj.16496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/22/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023]
Abstract
Attenuated strains of the naturally occurring plant pathogen Agrobacterium tumefaciens can transfer virtually any DNA sequence of interest to model plants and crops. This has made Agrobacterium-mediated transformation (AMT) one of the most commonly used tools in agricultural biotechnology. Understanding AMT, and its functional consequences, is of fundamental importance given that it sits at the intersection of many fundamental fields of study, including plant-microbe interactions, DNA repair/genome stability, and epigenetic regulation of gene expression. Despite extensive research and use of AMT over the last 40 years, the extent of genomic disruption associated with integrating exogenous DNA into plant genomes using this method remains underappreciated. However, new technologies like long-read sequencing make this disruption more apparent, complementing previous findings from multiple research groups that have tackled this question in the past. In this review, we cover progress on the molecular mechanisms involved in Agrobacterium-mediated DNA integration into plant genomes. We also discuss localized mutations at the site of insertion and describe the structure of these DNA insertions, which can range from single copy insertions to large concatemers, consisting of complex DNA originating from different sources. Finally, we discuss the prevalence of large-scale genomic rearrangements associated with the integration of DNA during AMT with examples. Understanding the intended and unintended effects of AMT on genome stability is critical to all plant researchers who use this methodology to generate new genetic variants.
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Affiliation(s)
- Geoffrey Thomson
- Yale University, Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences; New Haven, Connecticut 06511, USA
| | - Lauren Dickinson
- Yale University, Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences; New Haven, Connecticut 06511, USA
| | - Yannick Jacob
- Yale University, Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences; New Haven, Connecticut 06511, USA
- Yale Cancer Center, Yale School of Medicine; New Haven, Connecticut 06511, USA
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3
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Ferenczi A, Chew YP, Kroll E, von Koppenfels C, Hudson A, Molnar A. Mechanistic and genetic basis of single-strand templated repair at Cas12a-induced DNA breaks in Chlamydomonas reinhardtii. Nat Commun 2021; 12:6751. [PMID: 34799578 PMCID: PMC8604939 DOI: 10.1038/s41467-021-27004-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/26/2021] [Indexed: 12/12/2022] Open
Abstract
Single-stranded oligodeoxynucleotides (ssODNs) are widely used as DNA repair templates in CRISPR/Cas precision genome editing. However, the underlying mechanisms of single-strand templated DNA repair (SSTR) are inadequately understood, constraining rational improvements to precision editing. Here we study SSTR at CRISPR/Cas12a-induced DNA double-strand breaks (DSBs) in the eukaryotic model green microalga Chlamydomonas reinhardtii. We demonstrate that ssODNs physically incorporate into the genome during SSTR at Cas12a-induced DSBs. This process is genetically independent of the Rad51-dependent homologous recombination and Fanconi anemia pathways, is strongly antagonized by non-homologous end-joining, and is mediated almost entirely by the alternative end-joining enzyme polymerase θ. These findings suggest differences in SSTR between C. reinhardtii and animals. Our work illustrates the promising potentially of C. reinhardtii as a model organism for studying nuclear DNA repair.
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Affiliation(s)
- Aron Ferenczi
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Yen Peng Chew
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Erika Kroll
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK
- Department of Biointeractions and Crop Protection, Rothamsted Research, Harpenden, AL5 2JQ, UK
| | | | - Andrew Hudson
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Attila Molnar
- Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, EH9 3BF, UK.
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4
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Nishizawa-Yokoi A, Saika H, Hara N, Lee LY, Toki S, Gelvin SB. Agrobacterium T-DNA integration in somatic cells does not require the activity of DNA polymerase θ. THE NEW PHYTOLOGIST 2021; 229:2859-2872. [PMID: 33105034 DOI: 10.1111/nph.17032] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Integration of Agrobacterium tumefaciens transferred DNA (T-DNA) into the plant genome is the last step required for stable plant genetic transformation. The mechanism of T-DNA integration remains controversial, although scientists have proposed the participation of various nonhomologous end-joining (NHEJ) pathways. Recent evidence suggests that in Arabidopsis, DNA polymerase θ (PolQ) may be a crucial enzyme involved in T-DNA integration. We conducted quantitative transformation assays of wild-type and polQ mutant Arabidopsis and rice, analyzed T-DNA/plant DNA junction sequences, and (for Arabidopsis) measured the amount of integrated T-DNA in mutant and wild-type tissue. Unexpectedly, we were able to generate stable transformants of all tested lines, although the transformation frequency of polQ mutants was c. 20% that of wild-type plants. T-DNA/plant DNA junctions from these transformed rice and Arabidopsis polQ mutants closely resembled those from wild-type plants, indicating that loss of PolQ activity does not alter the characteristics of T-DNA integration events. polQ mutant plants show growth and developmental defects, perhaps explaining previous unsuccessful attempts at their stable transformation. We suggest that either multiple redundant pathways function in T-DNA integration, and/or that integration requires some yet unknown pathway.
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Affiliation(s)
- Ayako Nishizawa-Yokoi
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba, 305-8634, Japan
- Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Hiroaki Saika
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba, 305-8634, Japan
| | - Naho Hara
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba, 305-8634, Japan
| | - Lan-Ying Lee
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907-1392, USA
| | - Seiichi Toki
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 1-2 Owashi, Tsukuba, 305-8634, Japan
- Kihara Institute for Biological Research, Yokohama City University, 641-12, Maioka-cho, Yokohama, 244-0813, Japan
| | - Stanton B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907-1392, USA
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5
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Pereman I, Melamed-Bessudo C, Dahan-Meir T, Herz E, Elbaum M, Levy AA. Single Molecule Imaging of T-DNA Intermediates Following Agrobacterium tumefaciens Infection in Nicotiana benthamiana. Int J Mol Sci 2019; 20:ijms20246209. [PMID: 31835367 PMCID: PMC6940882 DOI: 10.3390/ijms20246209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/27/2019] [Accepted: 12/04/2019] [Indexed: 12/20/2022] Open
Abstract
Plant transformation mediated by Agrobacterium tumefaciens is a well-studied phenomenon in which a bacterial DNA fragment (T-DNA), is transferred to the host plant cell, as a single strand, via type IV secretion system and has the potential to reach the nucleus and to be integrated into its genome. While Agrobacterium-mediated transformation has been widely used for laboratory-research and in breeding, the time-course of its journey from the bacterium to the nucleus, the conversion from single- to double-strand intermediates and several aspects of the integration in the genome remain obscure. In this study, we sought to follow T-DNA infection directly using single-molecule live imaging. To this end, we applied the LacO-LacI imaging system in Nicotiana benthamiana, which enabled us to identify double-stranded T-DNA (dsT-DNA) molecules as fluorescent foci. Using confocal microscopy, we detected progressive accumulation of dsT-DNA foci in the nucleus, starting 23 h after transfection and reaching an average of 5.4 and 8 foci per nucleus at 48 and 72 h post-infection, respectively. A time-course diffusion analysis of the T-DNA foci has demonstrated their spatial confinement.
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Affiliation(s)
- Idan Pereman
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
- Migal, Galilee Research Institute, Kiryat Shmona 11016, Israel
- Correspondence: (I.P.); (M.E); (A.A.L.)
| | - Cathy Melamed-Bessudo
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tal Dahan-Meir
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Elad Herz
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Michael Elbaum
- Department of Chemical and Biological Physics, The Weizmann Institute of Science, Rehovot 76100, Israel
- Correspondence: (I.P.); (M.E); (A.A.L.)
| | - Avraham A. Levy
- Department of Plant and Environmental Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
- Correspondence: (I.P.); (M.E); (A.A.L.)
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6
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The Mechanism of T-DNA Integration: Some Major Unresolved Questions. Curr Top Microbiol Immunol 2018; 418:287-317. [DOI: 10.1007/82_2018_98] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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7
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Abstract
Agrobacterium strains transfer a single-strand form of T-DNA (T-strands) and Virulence (Vir) effector proteins to plant cells. Following transfer, T-strands likely form complexes with Vir and plant proteins that traffic through the cytoplasm and enter the nucleus. T-strands may subsequently randomly integrate into plant chromosomes and permanently express encoded transgenes, a process known as stable transformation. The molecular processes by which T-strands integrate into the host genome remain unknown. Although integration resembles DNA repair processes, the requirement of known DNA repair pathways for integration is controversial. The configuration and genomic position of integrated T-DNA molecules likely affect transgene expression, and control of integration is consequently important for basic research and agricultural biotechnology applications. This article reviews our current knowledge of the process of T-DNA integration and proposes ways in which this knowledge may be manipulated for genome editing and synthetic biology purposes.
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Affiliation(s)
- Stanton B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA;
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8
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Volokhina I, Gusev Y, Mazilov S, Moiseeva Y, Chumakov M. Computer evaluation of VirE2 protein complexes for ssDNA transfer ability. Comput Biol Chem 2017; 68:64-70. [DOI: 10.1016/j.compbiolchem.2017.01.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 01/23/2017] [Accepted: 01/23/2017] [Indexed: 11/16/2022]
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9
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Abstract
Historically, the members of the Agrobacterium genus have been considered the only bacterial species naturally able to transfer and integrate DNA into the genomes of their eukaryotic hosts. Yet, increasing evidence suggests that this ability to genetically transform eukaryotic host cells might be more widespread in the bacterial world. Indeed, analyses of accumulating genomic data reveal cases of horizontal gene transfer from bacteria to eukaryotes and suggest that it represents a significant force in adaptive evolution of eukaryotic species. Specifically, recent reports indicate that bacteria other than Agrobacterium, such as Bartonella henselae (a zoonotic pathogen), Rhizobium etli (a plant-symbiotic bacterium related to Agrobacterium), or even Escherichia coli, have the ability to genetically transform their host cells under laboratory conditions. This DNA transfer relies on type IV secretion systems (T4SSs), the molecular machines that transport macromolecules during conjugative plasmid transfer and also during transport of proteins and/or DNA to the eukaryotic recipient cells. In this review article, we explore the extent of possible transfer of genetic information from bacteria to eukaryotic cells as well as the evolutionary implications and potential applications of this transfer.
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10
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Ohmine Y, Satoh Y, Kiyokawa K, Yamamoto S, Moriguchi K, Suzuki K. DNA repair genes RAD52 and SRS2, a cell wall synthesis regulator gene SMI1, and the membrane sterol synthesis scaffold gene ERG28 are important in efficient Agrobacterium-mediated yeast transformation with chromosomal T-DNA. BMC Microbiol 2016; 16:58. [PMID: 27038795 PMCID: PMC4818910 DOI: 10.1186/s12866-016-0672-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/16/2016] [Indexed: 11/25/2022] Open
Abstract
Background Plant pathogenic Agrobacterium strains can transfer T-DNA regions of their Ti plasmids to a broad range of eukaryotic hosts, including fungi, in vitro. In the recent decade, the yeast Saccharomyces cerevisiae is used as a model host to reveal important host proteins for the Agrobacterium-mediated transformation (AMT). Further investigation is required to understand the fundamental mechanism of AMT, including interaction at the cell surface, to expand the host range, and to develop new tools. In this study, we screened a yeast mutant library for low AMT mutant strains by advantage of a chromosome type T-DNA, which transfer is efficient and independent on integration into host chromosome. Results By the mutant screening, we identified four mutant strains (srs2Δ, rad52Δ, smi1Δ and erg28Δ), which showed considerably low AMT efficiency. Structural analysis of T-DNA product replicons in AMT colonies of mutants lacking each of the two DNA repair genes, SRS2 and RAD52, suggested that the genes act soon after T-DNA entry for modification of the chromosomal T-DNA to stably maintain them as linear replicons and to circularize certain T-DNA simultaneously. The cell wall synthesis regulator SMI1 might have a role in the cell surface interaction between the donor and recipient cells, but the smi1Δ mutant exhibited pleiotropic effect, i.e. low effector protein transport as well as low AMT for the chromosomal T-DNA, but relatively high AMT for integrative T-DNAs. The ergosterol synthesis regulator/enzyme-scaffold gene ERG28 probably contributes by sensing a congested environment, because growth of erg28Δ strain was unaffected by the presence of donor bacterial cells, while the growth of the wild-type and other mutant yeast strains was suppressed by their presence. Conclusions RAD52 and the DNA helicase/anti-recombinase gene SRS2 are necessary to form and maintain artificial chromosomes through the AMT of chromosomal T-DNA. A sterol synthesis scaffold gene ERG28 is important in the high-efficiency AMT, possibly by avoiding congestion. The involvement of the cell wall synthesis regulator SMI1 remains to be elucidated.
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Affiliation(s)
- Yuta Ohmine
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Yukari Satoh
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Kazuya Kiyokawa
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Shinji Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Kazuki Moriguchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Katsunori Suzuki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
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11
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Kleinboelting N, Huep G, Appelhagen I, Viehoever P, Li Y, Weisshaar B. The Structural Features of Thousands of T-DNA Insertion Sites Are Consistent with a Double-Strand Break Repair-Based Insertion Mechanism. MOLECULAR PLANT 2015; 8:1651-64. [PMID: 26343971 DOI: 10.1016/j.molp.2015.08.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 07/28/2015] [Accepted: 08/13/2015] [Indexed: 05/06/2023]
Abstract
Transformation by Agrobacterium tumefaciens, an important tool in modern plant research, involves the integration of T-DNA initially present on a plasmid in agrobacteria into the genome of plant cells. The process of attachment of the agrobacteria to plant cells and the transport of T-DNA into the cell and further to the nucleus has been well described. However, the exact mechanism of integration into the host's DNA is still unclear, although several models have been proposed. During confirmation of T-DNA insertion alleles from the GABI-Kat collection of Arabidopsis thaliana mutants, we have generated about 34,000 sequences from the junctions between inserted T-DNA and adjacent genome regions. Here, we describe the evaluation of this dataset with regard to existing models for T-DNA integration. The results suggest that integration into the plant genome is mainly mediated by the endogenous plant DNA repair machinery. The observed integration events showed characteristics highly similar to those of repair sites of double-strand breaks with respect to microhomology and deletion sizes. In addition, we describe unexpected integration events, such as large deletions and inversions at the integration site that are relevant for correct interpretation of results from T-DNA insertion mutants in reverse genetics experiments.
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Affiliation(s)
- Nils Kleinboelting
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Gunnar Huep
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Ingo Appelhagen
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Prisca Viehoever
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany
| | - Yong Li
- Department of Medicine IV, University Hospital Freiburg, Berliner Allee 29, 79110 Freiburg, Germany
| | - Bernd Weisshaar
- Center for Biotechnology & Department of Biology, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany.
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12
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Enhanced targeted integration mediated by translocated I-SceI during the Agrobacterium mediated transformation of yeast. Sci Rep 2015; 5:8345. [PMID: 25662162 PMCID: PMC4648448 DOI: 10.1038/srep08345] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/15/2015] [Indexed: 12/21/2022] Open
Abstract
Agrobacterium mediated transformation (AMT) has been embraced by biotechnologists as the technology of choice to introduce or alter genetic traits of plants. However, in plants it is virtually impossible to predetermine the integration site of the transferred T-strand unless one is able to generate a double stranded break (DSB) in the DNA at the site of interest. In this study, we used the model organism Saccharomyces cerevisiae to investigate whether the Agrobacterium mediated translocation of site-specific endonucleases via the type IV secretion system (T4SS), concomitantly with T-DNA transfer is possible and whether this can improve the gene targeting efficiency. In addition to that, the effect of different chromatin states on targeted integration, was investigated. It was found that Agrobacterium mediated translocation of the homing endonuclease I-SceI has a positive effect on the integration of T-DNA via the homologous repair (HR) pathway. Furthermore, we obtained evidence that nucleosome removal has a positive effect on I-SceI facilitated T-DNA integration by HR. Reversely; inducing nucleosome formation at the site of integration removes the positive effect of translocated I-SceI on T-DNA integration.
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13
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Dafny-Yelin M, Levy A, Dafny R, Tzfira T. Blocking single-stranded transferred DNA conversion to double-stranded intermediates by overexpression of yeast DNA REPLICATION FACTOR A. PLANT PHYSIOLOGY 2015; 167:153-63. [PMID: 25424309 PMCID: PMC4281008 DOI: 10.1104/pp.114.250639] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 11/23/2014] [Indexed: 05/09/2023]
Abstract
Agrobacterium tumefaciens delivers its single-stranded transferred DNA (T-strand) into the host cell nucleus, where it can be converted into double-stranded molecules. Various studies have revealed that double-stranded transfer DNA (T-DNA) intermediates can serve as substrates by as yet uncharacterized integration machinery. Nevertheless, the possibility that T-strands are themselves substrates for integration cannot be ruled out. We attempted to block the conversion of T-strands into double-stranded intermediates prior to integration in order to further investigate the route taken by T-DNA molecules on their way to integration. Transgenic tobacco (Nicotiana benthamiana) plants that overexpress three yeast (Saccharomyces cerevisiae) protein subunits of DNA REPLICATION FACTOR A (RFA) were produced. In yeast, these subunits (RFA1-RFA3) function as a complex that can bind single-stranded DNA molecules, promoting the repair of genomic double strand breaks. Overexpression of the RFA complex in tobacco resulted in decreased T-DNA expression, as determined by infection with A. tumefaciens cells carrying the β-glucuronidase intron reporter gene. Gene expression was not blocked when the reporter gene was delivered by microbombardment. Enhanced green fluorescent protein-assisted localization studies indicated that the three-protein complex was predominantly nuclear, thus indicating its function within the plant cell nucleus, possibly by binding naked T-strands and blocking their conversion into double-stranded intermediates. This notion was further supported by the inhibitory effect of RFA expression on the cell-to-cell movement of Bean dwarf mosaic virus, a single-stranded DNA virus. The observation that RFA complex plants dramatically inhibited the transient expression level of T-DNA and only reduced T-DNA integration by 50% suggests that double-stranded T-DNA intermediates, as well as single-stranded T-DNA, play significant roles in the integration process.
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Affiliation(s)
- Mery Dafny-Yelin
- Golan Research Institute, University of Haifa, Qatzrin 12900, Israel (M.D.-Y., R.D.);Noga AgroTech Desert Agriculture, Kmehin 85511, Israel (A.L.);Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (R.D., T.T.); andDepartment of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel (T.T.)
| | - Avner Levy
- Golan Research Institute, University of Haifa, Qatzrin 12900, Israel (M.D.-Y., R.D.);Noga AgroTech Desert Agriculture, Kmehin 85511, Israel (A.L.);Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (R.D., T.T.); andDepartment of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel (T.T.)
| | - Raz Dafny
- Golan Research Institute, University of Haifa, Qatzrin 12900, Israel (M.D.-Y., R.D.);Noga AgroTech Desert Agriculture, Kmehin 85511, Israel (A.L.);Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (R.D., T.T.); andDepartment of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel (T.T.)
| | - Tzvi Tzfira
- Golan Research Institute, University of Haifa, Qatzrin 12900, Israel (M.D.-Y., R.D.);Noga AgroTech Desert Agriculture, Kmehin 85511, Israel (A.L.);Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (R.D., T.T.); andDepartment of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel (T.T.)
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14
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Rolloos M, Dohmen MHC, Hooykaas PJJ, van der Zaal BJ. Involvement of Rad52 in T-DNA circle formation duringAgrobacterium tumefaciens-mediated transformation ofSaccharomyces cerevisiae. Mol Microbiol 2014; 91:1240-51. [DOI: 10.1111/mmi.12531] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Martijn Rolloos
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
| | - Marius H. C. Dohmen
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
| | - Paul J. J. Hooykaas
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
| | - Bert J. van der Zaal
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
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Saika H, Nishizawa-Yokoi A, Toki S. The non-homologous end-joining pathway is involved in stable transformation in rice. FRONTIERS IN PLANT SCIENCE 2014; 5:560. [PMID: 25368624 PMCID: PMC4201092 DOI: 10.3389/fpls.2014.00560] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 09/29/2014] [Indexed: 05/20/2023]
Abstract
Stable transformation with T-DNA needs the coordinated activities of many proteins derived from both host plant cells and Agrobacterium. In dicot plants, including Arabidopsis, it has been suggested that non-homologous end-joining (NHEJ)-one of the main DNA double-strand break repair pathways-is involved in the T-DNA integration step that is crucial to stable transformation. However, how this pathway is involved remains unclear as results with NHEJ mutants in Arabidopsis have given inconsistent results. Recently, a system for visualization of stable expression of genes located on T-DNA has been established in rice callus. Stable expression was shown to be reduced significantly in NHEJ knock-down rice calli, suggesting strongly that NHEJ is involved in Agrobacterium-mediated stable transformation in rice. Since rice transformation is now efficient and reproducible, rice is a good model plant in which to elucidate the molecular mechanisms of T-DNA integration.
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Affiliation(s)
- Hiroaki Saika
- Plant Genome Engineering Research Unit, Agrogenomics Research Center, National Institute of Agrobiological SciencesTsukuba, Japan
- *Correspondence: Hiroaki Saika, Plant Genome Engineering Research Unit, Agrogenomics Research Center, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan e-mail:
| | - Ayako Nishizawa-Yokoi
- Plant Genome Engineering Research Unit, Agrogenomics Research Center, National Institute of Agrobiological SciencesTsukuba, Japan
| | - Seiichi Toki
- Plant Genome Engineering Research Unit, Agrogenomics Research Center, National Institute of Agrobiological SciencesTsukuba, Japan
- Kihara Institute for Biological Research, Yokohama City UniversityYokohama, Japan
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