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Abstract
When first asked to write a review of my life as a scientist, I doubted anyone would be interested in reading it. In addition, I did not really want to compose my own memorial. However, after discussing the idea with other scientists who have written autobiographies, I realized that it might be fun to dig into my past and to reflect on what has been important for me, my life, my family, my friends and colleagues, and my career. My life and research has taken me from bacteriophage to Agrobacterium tumefaciens-mediated DNA transfer to plants to the plant genome and its environmentally induced changes. I went from being a naïve, young student to a postdoc and married mother of two to the leader of an ever-changing group of fantastic coworkers-a journey made rich by many interesting scientific milestones, fascinating exploration of all corners of the world, and marvelous friendships.
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Affiliation(s)
- Barbara Hohn
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland;
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2
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Hull R. Replication of Plant Viruses. PLANT VIROLOGY 2014. [PMCID: PMC7184227 DOI: 10.1016/b978-0-12-384871-0.00007-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Viruses replicate using both their own genetic information and host cell components and machinery. The different genome types have different replication pathways which contain controls on linking the process with translation and movement around the cell as well as not compromising the infected cell. This chapter discusses the replication mechanisms, faults in replication and replication of viruses co-infecting cells. Viruses replicate using both their own genetic information and host cell components and machinery. The different genome types have different replication pathways which contain controls on linking the process with translation and movement around the cell as well as not compromising the infected cell. This chapter discusses the replication mechanisms, faults in replication and replication of viruses coinfecting cells.
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3
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Squires J, Gillespie T, Schoelz JE, Palukaitis P. Excision and episomal replication of cauliflower mosaic virus integrated into a plant genome. PLANT PHYSIOLOGY 2011; 155:1908-1919. [PMID: 21278309 PMCID: PMC3091124 DOI: 10.1104/pp.110.171611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 01/25/2011] [Indexed: 05/30/2023]
Abstract
Transgenic Arabidopsis (Arabidopsis thaliana) plants containing a monomeric copy of the cauliflower mosaic virus (CaMV) genome exhibited the generation of infectious, episomally replicating virus. The circular viral genome had been split within the nonessential gene II for integration into the Arabidopsis genome by Agrobacterium tumefaciens-mediated transformation. Transgenic plants were assessed for episomal infections at flowering, seed set, and/or senescence. The infections were confirmed by western blot for the CaMV P6 and P4 proteins, electron microscopy for the presence of icosahedral virions, and through polymerase chain reaction across the recombination junction. By the end of the test period, a majority of the transgenic Arabidopsis plants had developed episomal infections. The episomal form of the virus was infectious to nontransgenic plants, indicating that no essential functions were lost after release from the Arabidopsis chromosome. An analysis of the viral genomes recovered from either transgenic Arabidopsis or nontransgenic turnip (Brassica rapa var rapa) revealed that the viruses contained deletions within gene II, and in some cases, the deletions extended to the beginning of gene III. In addition, many of the progeny viruses contained small regions of nonviral sequence derived from the flanking transformation vector. The nature of the nucleotide sequences at the recombination junctions in the circular progeny virus indicated that most were generated by nonhomologous recombination during the excision event. The release of the CaMV viral genomes from an integrated copy was not dependent upon the application of environmental stresses but occurred with greater frequency with either age or the late stages of plant maturation.
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4
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Grimsley N, Hohn B, Hohn T, Walden R. "Agroinfection," an alternative route for viral infection of plants by using the Ti plasmid. Proc Natl Acad Sci U S A 2010; 83:3282-6. [PMID: 16593697 PMCID: PMC323497 DOI: 10.1073/pnas.83.10.3282] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most plant viruses are transmitted by insect vectors. We present an alternative method for the introduction of infectious viral DNA that uses the ability of Agrobacterium to transfer DNA from bacterial cells to plants. Cauliflower mosaic virus was chosen to develop this method because it is the best characterized plant DNA virus and can be introduced into plants via aphids, virus particles, viral DNA, or suitably treated cloned DNA. We show that systemic infection of turnips results from wounding and inoculation with strains of Agrobacterium tumefaciens in which more than one genome of cauliflower mosaic virus have been placed tandemly in the T-DNA of the tumor-inducing plasmid. Thus such constructions allow escape of the viral genome from the T-DNA once inside the plants. The combined use of the tumor-inducing plasmid and viral DNA opens the way to molecular biological approaches that are not possible with either system alone.
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Affiliation(s)
- N Grimsley
- Friedrich Miescher-Institut, P.O. Box 2543, CH4002 Basel, Switzerland
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5
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Xiong C, Lebeurier G, Hirth L. Detection in vivo of a new gene product (gene III) of cauliflower mosaic virus. Proc Natl Acad Sci U S A 2010; 81:6608-12. [PMID: 16593524 PMCID: PMC391979 DOI: 10.1073/pnas.81.21.6608] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cauliflower mosaic virus DNA contains six major open reading frames (ORFs). As only the mRNA corresponding to the transcription of gene VI and its translation product have been isolated, the identification in infected plants of products corresponding to the five other putative genes remains to be established. The present paper reports the detection of an ORF III product by means of antibodies raised against an NH(2)-terminal synthetic peptide of 19 amino acids corresponding to a sequence predicted from the nucleotide sequence of ORF III. The detection of this gene product raises the question of the mechanism of its expression.
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Affiliation(s)
- C Xiong
- Laboratoire de Virologie, Institut de Biologie Moléculaire et Cellulaire du Centre National de la Recherche Scientifique, 15 rue Descartes, 67084 Strasbourg Cédex, France
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6
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Cabauatan PQ, Melcher U, Ishikawa K, Omura T, Hibino H, Koganezawa H, Azzam O. Sequence changes in six variants of rice tungro bacilliform virus and their phylogenetic relationships. J Gen Virol 1999; 80 ( Pt 8):2229-2237. [PMID: 10466823 DOI: 10.1099/0022-1317-80-8-2229] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The DNA of three biological variants, G1, Ic and G2, which originated from the same greenhouse isolate of rice tungro bacilliform virus (RTBV) at the International Rice Research Institute (IRRI), was cloned and sequenced. Comparison of the sequences revealed small differences in genome sizes. The variants were between 95 and 99% identical at the nucleotide and amino acid levels. Alignment of the three genome sequences with those of three published RTBV sequences (Phi-1, Phi-2 and Phi-3) revealed numerous nucleotide substitutions and some insertions and deletions. The published RTBV sequences originated from the same greenhouse isolate at IRRI 20, 11 and 9 years ago. All open reading frames (ORFs) and known functional domains were conserved across the six variants. The cysteine-rich region of ORF3 showed the greatest variation. When the six DNA sequences from IRRI were compared with that of an isolate from Malaysia (Serdang), similar changes were observed in the cysteine-rich region in addition to other nucleotide substitutions and deletions across the genome. The aligned nucleotide sequences of the IRRI variants and Serdang were used to analyse phylogenetic relationships by the bootstrapped parsimony, distance and maximum-likelihood methods. The isolates clustered in three groups: Serdang alone; Ic and G1; and Phi-1, Phi-2, Phi-3 and G2. The distribution of phylogenetically informative residues in the IRRI sequences shared with the Serdang sequence and the differing tree topologies for segments of the genome suggested that recombination, as well as substitutions and insertions or deletions, has played a role in the evolution of RTBV variants. The significance and implications of these evolutionary forces are discussed in comparison with badnaviruses and caulimoviruses.
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Affiliation(s)
- Pepito Q Cabauatan
- Entomology and Plant Pathology Division, International Rice Research Institute, PO Box 933, 1099 Manila, Philippines1
| | | | - Koichi Ishikawa
- National Agriculture Research Center, Tsukuba 305-0856, Japan3
| | - Toshihiro Omura
- National Agriculture Research Center, Tsukuba 305-0856, Japan3
| | - Hiroyuki Hibino
- National Institute for Agroenvironmental Science, Tsukuba 305-8604, Japan4
| | - Hiroki Koganezawa
- Shikoku National Agricultural Experiment Station, Zentsuji, Kagawa 765-0001, Japan5
| | - Ossmat Azzam
- Entomology and Plant Pathology Division, International Rice Research Institute, PO Box 933, 1099 Manila, Philippines1
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7
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Leclerc D, Burri L, Kajava AV, Mougeot JL, Hess D, Lustig A, Kleemann G, Hohn T. The open reading frame III product of cauliflower mosaic virus forms a tetramer through a N-terminal coiled-coil. J Biol Chem 1998; 273:29015-21. [PMID: 9786907 DOI: 10.1074/jbc.273.44.29015] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The open reading frame III product of cauliflower mosaic virus is a protein of 15 kDa (p15) that is essential for the virus life cycle. It was shown that the 34 N-terminal amino acids are sufficient to support protein-protein interaction with the full-length p15 in the yeast two-hybrid system. A corresponding peptide was synthesized and a recombinant p15 was expressed in Escherichia coli and purified. Circular dichroism spectroscopy showed that the peptide and the full-length protein can assume an alpha-helical conformation. Analytical centrifugation allowed to determine that p15 assembles as a rod-shaped tetramer. Oxidative cross-linking of N-terminal cysteines of the peptide generated specific covalent oligomers, indicating that the N terminus of p15 is a coiled-coil that assembles as a parallel tetramer. Mutation of Lys22 into Asp destabilized the tetramer and put forward the presence of a salt bridge between Lys22 and Asp24 in a model building of the stalk. These results suggest a model in which the stalk segment of p15 is located at its N terminus, followed by a hinge that provides the space for presenting the C terminus for interactions with nucleic acids and/or proteins.
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Affiliation(s)
- D Leclerc
- Friedrich Miescher Institut, P. O. Box 2543, CH-4002 Basel, Switzerland
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8
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Jacquot E, Geldreich A, Keller M, Yot P. Mapping regions of the cauliflower mosaic virus ORF III product required for infectivity. Virology 1998; 242:395-402. [PMID: 9514961 DOI: 10.1006/viro.1997.8995] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The open reading frame (ORF) III product (PIII) of the pararetrovirus cauliflower mosaic virus (CaMV) has nucleic acid-binding properties in vitro, but its biological role is not yet determined. ORF III is closely linked to ORF II and overlaps ORF IV out of frame in the CaMV genome. A new CaMV-derived vector (Ca delta) devoid of ORF III and containing unique restriction sites between ORFs II and IV was designed. Introduction of the wild-type CaMV ORF III into Ca delta results in a clone (Ca3) infectious in turnip plants. Truncated or point-mutated versions of ORF III were then inserted into Ca delta and tested in vivo. Inoculation of the different mutants into turnip revealed that the four C-terminal amino acid residues of PIII are dispensable for infectivity as well as an internal domain (amino acids 61 to 80). Taken together the results show that PIII possesses a functional two-domain organization. Moreover, the CaMV PIII function(s) cannot be replaced either by the PIII protein of another caulimovirus, the figwort mosaic virus, or by the P2 protein of the cacao swollen shoot badnavirus, a member of the second plant pararetrovirus group.
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Affiliation(s)
- E Jacquot
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Université Louis Pasteur, Strasbourg, France
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9
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Abstract
Plant viruses utilize several mechanisms to generate the large amount of genetic diversity found both within and between species. Plant RNA viruses and pararetroviruses probably have highly error prone replication mechanisms, that result in numerous mutations and a quasispecies nature. The plant DNA viruses also exhibit diversity, but the source of this is less clear. Plant viruses frequently use recombination and reassortment as driving forces in evolution, and, occasionally, other mechanisms such as gene duplication and overprinting. The amount of variation found in different species of plant viruses is remarkably different, even though there is no evidence that the mutation rate varies. The origin of plant viruses is uncertain, but several possible theories are proposed. The relationships between some plant and animal viruses suggests a common origin, possibly an insect virus. The propensity for rapid adaptation makes tracing the evolutionary history of viruses difficult, and long term control of virus disease nearly impossible, but it provides an excellent model system for studying general mechanisms of molecular evolution.
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Affiliation(s)
- M J Roossinck
- Plant Biology Division, The S.R. Noble Foundation, Ardmore, Oklahoma 73402-2180, USA.
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10
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Abstract
Autonomously replicating virus-based vectors have been investigated as a means of introducing heterologous genes into plants. This approach has a number of potential advantages over stable genetic transformation, particularly in terms of speed and levels of expression that can be obtained. Several groups of plant viruses, with genomes consisting of both DNA and RNA, have been investigated as possible gene vectors. In the case of DNA viruses, it has generally been possible to identify nonessential regions of the genome that can be replaced by foreign sequences. However, there appear to be limitations on the size of insert which can be tolerated. In the case of RNA viruses, replacement of viral sequences usually has a drastic effect on the viability. However, in several cases it has proved possible to substantially increase the size of the viral genome by the direct insertion of additional sequences while still retaining the ability of the viruses to multiply and spread in plants. These RNA virus-based systems appear to have the greatest potential as gene vectors.
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Affiliation(s)
- C Porta
- Department of Virus Research, John Innes Centre, Norwich, UK
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11
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12
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Extrachromosomal homologous DNA recombination in plant cells is fast and is not affected by CpG methylation. Mol Cell Biol 1992. [PMID: 1630452 DOI: 10.1128/mcb.12.8.3372] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using a sensitive transient assay, we investigated extrachromosomal homologous DNA recombination (ECR) in plant cells. As the plant genome is highly C methylated, we addressed the question of whether CpG methylation has an influence on DNA recombination efficiencies. Whereas the expression level of the fully CpG-methylated DNA molecules was reduced drastically, we found no significant changes in ECR efficiencies between two partly CpG-methylated plasmids or between one fully CpG-methylated and one nonmethylated plasmid. Using a modified polymerase chain reaction analysis, we were able to detect recombination between two fully CpG-methylated plasmids. Furthermore, we characterized the kinetics of the ECR reaction. Cotransfection of plasmids carrying truncated copies of the beta-glucuronidase (GUS) gene resulted in enzyme activity with a delay of only half an hour compared with that of the plasmid carrying the functional marker gene. This indicates that the ECR reaction itself requires no more than 30 min. By polymerase chain reaction, we were able to detect the recombined GUS gene as early as 2 h after transfection. This result and the time course of the transient GUS activity indicate that ECR occurs mainly early after transfection. The biological significance of this finding is discussed, and properties of ECR and intrachromosomal recombination are compared.
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13
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Puchta H, Kocher S, Hohn B. Extrachromosomal homologous DNA recombination in plant cells is fast and is not affected by CpG methylation. Mol Cell Biol 1992; 12:3372-9. [PMID: 1630452 PMCID: PMC364585 DOI: 10.1128/mcb.12.8.3372-3379.1992] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Using a sensitive transient assay, we investigated extrachromosomal homologous DNA recombination (ECR) in plant cells. As the plant genome is highly C methylated, we addressed the question of whether CpG methylation has an influence on DNA recombination efficiencies. Whereas the expression level of the fully CpG-methylated DNA molecules was reduced drastically, we found no significant changes in ECR efficiencies between two partly CpG-methylated plasmids or between one fully CpG-methylated and one nonmethylated plasmid. Using a modified polymerase chain reaction analysis, we were able to detect recombination between two fully CpG-methylated plasmids. Furthermore, we characterized the kinetics of the ECR reaction. Cotransfection of plasmids carrying truncated copies of the beta-glucuronidase (GUS) gene resulted in enzyme activity with a delay of only half an hour compared with that of the plasmid carrying the functional marker gene. This indicates that the ECR reaction itself requires no more than 30 min. By polymerase chain reaction, we were able to detect the recombined GUS gene as early as 2 h after transfection. This result and the time course of the transient GUS activity indicate that ECR occurs mainly early after transfection. The biological significance of this finding is discussed, and properties of ECR and intrachromosomal recombination are compared.
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Affiliation(s)
- H Puchta
- Friedrich Miescher-Institut, Basel, Switzerland
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14
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15
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Steinbiss HH, Davidson A. Transient gene expression of chimeric genes in cells and tissues of crops. Subcell Biochem 1991; 17:143-66. [PMID: 1796483 DOI: 10.1007/978-1-4613-9365-8_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- H H Steinbiss
- Max-Planck Institut für Züchtungsforschung, Abt. Genetische Grundlagen der Pflanzenzüchtung, Köln, Germany
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16
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Offringa R, de Groot MJ, Haagsman HJ, Does MP, van den Elzen PJ, Hooykaas PJ. Extrachromosomal homologous recombination and gene targeting in plant cells after Agrobacterium mediated transformation. EMBO J 1990; 9:3077-84. [PMID: 2209538 PMCID: PMC552033 DOI: 10.1002/j.1460-2075.1990.tb07504.x] [Citation(s) in RCA: 119] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We determined whether T-DNA molecules introduced into plant cells using Agrobacterium are suitable substrates for homologous recombination. For the detection of such recombination events different mutant versions of a NPTII construct were used. In a first set of experiments protoplasts of Nicotiana tabacum SR1 were cocultivated with two Agrobacterium tumefaciens strains. Each strain contained a different T-DNA, one carrying a 5' deleted NPTII gene and the other a NPTII gene with a 3' deletion. A restored NPTII gene was found in 1-4% of the protoplasts that had been cotransformed with both T-DNAs. Restoration of the NPTII gene could only be the consequence of homologous recombination between the two different T-DNAs in the plant cell, since the possibility of recombination in Agrobacterium was excluded in control experiments. In subsequent experiments was investigated the potential use of Agrobacterium for gene targeting in plants. A transgenic tobacco line with a T-DNA insertion carrying a defective NPTII gene with a 3' deletion was transformed via Agrobacterium with a T-DNA containing a defective NPTII repair gene. Several kanamycin resistant plant lines were obtained with an intact NPTII gene integrated in their genome. In one of these lines the defective NPTII gene at the target locus had been properly restored. Our results show that in plants recombination can occur between a chromosomal locus and a homologous T-DNA introduced via A. tumefaciens. This opens the possibility of using the Agrobacterium transformation system for site directed mutagenesis of the plant genome.
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Affiliation(s)
- R Offringa
- MOGEN International nv, CB Leiden, The Netherlands
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17
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Odell J, Caimi P, Sauer B, Russell S. Site-directed recombination in the genome of transgenic tobacco. MOLECULAR & GENERAL GENETICS : MGG 1990; 223:369-78. [PMID: 2176714 DOI: 10.1007/bf00264442] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The plant genome responds to the bacteriophage P1-derived loxP-Cre site-specific recombination system. Recombination took place at loxP sites stably integrated in the tobacco genome, indicating that the Cre recombinase protein, expressed by a chimeric gene also stably resident in the genome, was able to enter the nucleus and to locate a specific 34 bp DNA sequence. An excisional recombination event was monitored by the acquisition of kanamycin resistance, which resulted from the loss of a polyadenylation signal sequence that interrupted a chimeric neomycin phosphotransferase II gene. Molecular analysis confirmed that the excision had occurred. Recombination occurred when plants with the integrated loxP construction were stably re-transformed with a chimeric cre gene and when plants with the introduced loxP construction were cross-bred with those carrying the chimeric cre gene. As assayed phenotypically, site-specific recombination could be detected in 50%-100% of the plants containing both elements of the system. Kanamycin resistance was detected at 2-3 weeks after re-transformation and in the first leaf of hybrid seedlings. This demonstration of the effectiveness of the loxP-Cre system in plants provides the basis for development of this system for such purposes as directing site-specific integration and regulation of gene expression.
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Affiliation(s)
- J Odell
- Agricultural Products Department, E.I. DuPont de Nemours and Co., Wilmington, Delaware 19880-0402
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18
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Abstract
To study DNA topological requirements for homologous recombination in plants, we have constructed pairs of plasmids that contain nonoverlapping deletions in the neomycin phosphotransferase gene [APH(3')II], which, when intact, confers kanamycin resistance to plant cells. Protoplasts isolated from Nicotiana tabacum were cotransformed with complementary pairs of plasmids containing these truncated gene constructs. Homologous recombination or gene conversion within the homologous sequences (6 to 405 base pairs) of the protein-coding region of the truncated genes led to the restoration of the functional APH(3')II gene, rendering these cells resistant to kanamycin. Circular plasmid DNAs recombined very inefficiently, independent of the length of the homologous region. A double-strand break in one molecule only slightly increased the recombination frequency. The most favorable substrates for recombination were linear molecules. In this case, the recombination frequency was positively correlated with the length of the homologous regions. The recombination frequency of plasmids linearized at sites proximal to the deletion-homology junction was significantly higher than when linearization was distal to the homologous region. Vector homology within cotransformed plasmid sequences also increased the recombination frequency.
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19
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Abstract
To study DNA topological requirements for homologous recombination in plants, we have constructed pairs of plasmids that contain nonoverlapping deletions in the neomycin phosphotransferase gene [APH(3')II], which, when intact, confers kanamycin resistance to plant cells. Protoplasts isolated from Nicotiana tabacum were cotransformed with complementary pairs of plasmids containing these truncated gene constructs. Homologous recombination or gene conversion within the homologous sequences (6 to 405 base pairs) of the protein-coding region of the truncated genes led to the restoration of the functional APH(3')II gene, rendering these cells resistant to kanamycin. Circular plasmid DNAs recombined very inefficiently, independent of the length of the homologous region. A double-strand break in one molecule only slightly increased the recombination frequency. The most favorable substrates for recombination were linear molecules. In this case, the recombination frequency was positively correlated with the length of the homologous regions. The recombination frequency of plasmids linearized at sites proximal to the deletion-homology junction was significantly higher than when linearization was distal to the homologous region. Vector homology within cotransformed plasmid sequences also increased the recombination frequency.
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Affiliation(s)
- M Baur
- Friedrich Miescher Institute, Basel, Switzerland
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20
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Penswick J, Hübler R, Hohn T. A viable mutation in cauliflower mosaic virus, a retroviruslike plant virus, separates its capsid protein and polymerase genes. J Virol 1988; 62:1460-3. [PMID: 2894473 PMCID: PMC253163 DOI: 10.1128/jvi.62.4.1460-1463.1988] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A viable strain of cauliflower mosaic virus is described which arose by illegitimate recombination of two lethal parents. In this strain, the normally overlapping open reading frames IV and V, corresponding to the retrovirus gag and pol genes, are separated by a short intergenic region, suggesting that in this virus and in contrast to retroviruses, fusion of gag and pol gene products is not obligatory.
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Affiliation(s)
- J Penswick
- Friedrich-Miescher-Institut, Basel, Switzerland
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21
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The Molecular Biology of Cauliflower Mosaic Virus and Its Application as Plant Gene Vector. ACTA ACUST UNITED AC 1987. [DOI: 10.1007/978-3-7091-6977-3_1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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22
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23
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Paszkowski J, Pisan B, Shillito RD, Hohn T, Hohn B, Potrykus I. Genetic transformation of Brassica campestris var. rapa protoplasts with an engineered cauliflower mosaic virus genome. PLANT MOLECULAR BIOLOGY 1986; 6:303-312. [PMID: 24307380 DOI: 10.1007/bf00034937] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/1985] [Revised: 01/09/1986] [Accepted: 01/14/1986] [Indexed: 06/02/2023]
Abstract
A hybrid Cauliflower Mosaic Virus (CaMV) genome containing a selectable marker gene was constructed by replacing the gene VI coding region with the aminoglycoside (neomycin) phosphotransferase type II [APH(3')II] gene from Tn5. This modified viral genome was tested for its infectivity both in planta and in a protoplast transformation system of Brassica campestris var. rapa. Stable, genetically transformed cell lines of B. campestris var. rapa were obtained after transformation. DNA of the hybrid CaMV genome was found to be integrated into high molecular weight plant genomic DNA. Transformation was achieved only when the hybrid genome was supplied together with wild type viral DNA. A possible complementation of the modified CaMV genome with the wild type viral DNA as a helper molecule in planta and in the protoplast system is discussed.
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Affiliation(s)
- J Paszkowski
- Friedrich Miescher Institut, P.O. Box 2543, CH-4002, Basel, Switzerland
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24
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Melcher U, Choe IS, Lebeurier G, Richards K, Essenberg RC. Selective allele loss and interference between cauliflower mosaic virus DNAs. ACTA ACUST UNITED AC 1986. [DOI: 10.1007/bf00333959] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Yadav NS. Molecular biology of plant cell transformation. Results Probl Cell Differ 1986; 12:109-42. [PMID: 3529269 DOI: 10.1007/978-3-540-39836-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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26
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Choe IS, Melcher U, Richards K, Lebeurier G, Essenberg RC. Recombination between mutant cauliflower mosaic virus DNAs. PLANT MOLECULAR BIOLOGY 1985; 5:281-289. [PMID: 24306919 DOI: 10.1007/bf00020625] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/1985] [Revised: 08/30/1985] [Accepted: 09/04/1985] [Indexed: 06/02/2023]
Abstract
A class of mutants of cauliflower mosaic virus (CaMV) DNA was distinguished based on its members' ability to induce symptoms when coinoculated on plants with other CaMV DNAs mutant at a different locus. Three mutants, one each in open reading frame I, III, and VI had this ability. A second class of mutant DNAs did not induce symptoms unless combined with a mutant DNA of the first class. Viral DNA extracted from diseased plants was shown by restriction enzyme digestion to have lost the mutant alleles. When turnip plants were inoculated with a recombining mutant derived from DNA of the Cabbage S isolate and a mutant derived from DNA of a different isolate, a heterogeneity in the viral DNA extracted from the diseased plants was detected by restriction enzyme analysis. Restriction analysis of cloned representatives of this heterogeneous population revealed regions consistent with repair of heteroduplexes formed during general recombination between duplex DNAs. Some regions consistent with this mechanism or with recombination by strandswitching during reverse transcription were found.
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Affiliation(s)
- I S Choe
- Department of Biochemistry, Oklahoma State University, 74078, Stillwater, OK, U.S.A
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Meshi T, Ishikawa M, Watanabe Y, Yamaya J, Okada Y, Sano T, Shikata E. The sequence necessary for the infectivity of hop stunt viroid cDNA clones. ACTA ACUST UNITED AC 1985. [DOI: 10.1007/bf00425424] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Relatively little is known about the damage suffered by transfected DNA molecules during their journey from outside the cell into the nucleus. To follow selectively the minor subpopulation that completes this journey, we devised a genetic approach using simian virus 40 DNA transfected with DEAE-dextran. We investigated this active subpopulation in three ways: (i) by assaying reciprocal pairs of mutant linear dimers which differed only in the arrangement of two mutant genomes; (ii) by assaying a series of wild-type oligomers which ranged from 1.1 to 2.0 simian virus 40 genomes in length; and (iii) by assaying linear monomers of simian virus 40 which were cleaved within a nonessential region to leave either sticky, blunt, or mismatched ends. We conclude from these studies that transfected DNA molecules in the active subpopulation are moderately damaged by fragmentation and modification of ends. As a whole, the active subpopulation suffers about one break per 5 to 15 kilobases, and about 15 to 20% of the molecules have one or both ends modified. Our analysis of fragmentation is consistent with the random introduction of double-strand breaks, whose cause and exact nature are unknown. Our analysis of end modification indicated that the most prevalent form of damage involved deletion or addition of less than 25 base pairs. In addition we demonstrated directly that the efficiencies of joining sticky, blunt, or mismatched ends are identical, verifying the apparent ability of cells to join nearly any two DNA ends and suggesting that the efficiency of joining approaches 100%. The design of these experiments ensured that the detected damage preceded viral replication and thus should be common to all DNAs transfected with DEAE-dextran and not specific for viral DNA. These measurements of damage within transfected DNA have important consequences for studies of homologous and nonhomologous recombination in somatic cells as is discussed.
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E. coli spheroplast-mediated transfer of cloned cauliflower mosaic virus DNA into plant protoplasts. ACTA ACUST UNITED AC 1984. [DOI: 10.1007/bf00332778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Molecular cloning of adeno-associated virus variant genomes and generation of infectious virus by recombination in mammalian cells. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43097-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Wake CT, Gudewicz T, Porter T, White A, Wilson JH. How damaged is the biologically active subpopulation of transfected DNA? Mol Cell Biol 1984; 4:387-98. [PMID: 6325874 PMCID: PMC368715 DOI: 10.1128/mcb.4.3.387-398.1984] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Relatively little is known about the damage suffered by transfected DNA molecules during their journey from outside the cell into the nucleus. To follow selectively the minor subpopulation that completes this journey, we devised a genetic approach using simian virus 40 DNA transfected with DEAE-dextran. We investigated this active subpopulation in three ways: (i) by assaying reciprocal pairs of mutant linear dimers which differed only in the arrangement of two mutant genomes; (ii) by assaying a series of wild-type oligomers which ranged from 1.1 to 2.0 simian virus 40 genomes in length; and (iii) by assaying linear monomers of simian virus 40 which were cleaved within a nonessential region to leave either sticky, blunt, or mismatched ends. We conclude from these studies that transfected DNA molecules in the active subpopulation are moderately damaged by fragmentation and modification of ends. As a whole, the active subpopulation suffers about one break per 5 to 15 kilobases, and about 15 to 20% of the molecules have one or both ends modified. Our analysis of fragmentation is consistent with the random introduction of double-strand breaks, whose cause and exact nature are unknown. Our analysis of end modification indicated that the most prevalent form of damage involved deletion or addition of less than 25 base pairs. In addition we demonstrated directly that the efficiencies of joining sticky, blunt, or mismatched ends are identical, verifying the apparent ability of cells to join nearly any two DNA ends and suggesting that the efficiency of joining approaches 100%. The design of these experiments ensured that the detected damage preceded viral replication and thus should be common to all DNAs transfected with DEAE-dextran and not specific for viral DNA. These measurements of damage within transfected DNA have important consequences for studies of homologous and nonhomologous recombination in somatic cells as is discussed.
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Cress DE, Kiefer MC, Owens RA. Construction of infectious potato spindle tuber viroid cDNA clones. Nucleic Acids Res 1983; 11:6821-35. [PMID: 6314259 PMCID: PMC326416 DOI: 10.1093/nar/11.19.6821] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Contiguous restriction fragments from two cloned partial-length potato spindle tuber viroid (PSTV) cDNAs were used to construct recombinant DNAs containing full-length monomeric and dimeric PSTV cDNA. When five different PSTV cDNA plasmids and RNA isolated from E. coli cells harboring these plasmids were tested for infectivity on tomato, plasmid DNAs containing PSTV cDNA dimers were infectious. RNA transcripts containing the sequence of PSTV from these plasmids were also infectious. The sequences of the viroid progeny and the cloned DNA were identical. In vitro mutagenesis of infectious PSTV cDNAs will allow systematic investigation of the role of specific sequences in viroid replication and pathogenesis.
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Matsui C, Hasezawa S, Tanaka N, Syono K. Introduction of Escherichia coli cells and spheroplasts into Vinca protoplasts. PLANT CELL REPORTS 1983; 2:30-32. [PMID: 24257851 DOI: 10.1007/bf00269230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/1982] [Indexed: 06/02/2023]
Abstract
In the presence of 10% polyvinyl alcohol (PVA), Escherichia coli cells or spheroplasts can be easily introduced into Vinca protoplasts by endocytosis. Uptake proceeded quite rapidly; bacterial cells or spheroplasts were found within the cytoplasm of Vinca protoplasts after 10 min of incubation with PVA.
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Affiliation(s)
- C Matsui
- Plant Pathology Laboratory, Faculty of Agriculture, Nagoya University, Nagoya
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