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Construction of Infectious Clones of Begomoviruses: Strategies, Techniques and Applications. BIOLOGY 2021; 10:biology10070604. [PMID: 34209952 PMCID: PMC8301103 DOI: 10.3390/biology10070604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/21/2021] [Accepted: 06/24/2021] [Indexed: 11/24/2022]
Abstract
Simple Summary Begomovirus has a wide host range and threatens a significant amount of economic damage to many important crops such as tomatoes, beans, cassava, squash and cotton. There are many efforts directed at controlling this disease including the use of insecticides to control the insect vector as well as screening the resistant varieties. The use of synthetic virus or infectious clones approaches has allowed plant virologists to characterize and exploit the genome virus at the molecular and biological levels. By exploiting the DNA of the virus using the infectious clones strategy, the viral genome can be manipulated at specific regions to study functional genes for host–virus interactions. Thus, this review will provide an overview of the strategy to construct infectious clones of Begomovirus. The significance of established infectious clones in Begomovirus study will also be discussed. Abstract Begomovirus has become a potential threat to the agriculture sector. It causes significant losses to several economically important crops. Given this considerable loss, the development of tools to study viral genomes and function is needed. Infectious clones approaches and applications have allowed the direct exploitation of virus genomes. Infectious clones of DNA viruses are the critical instrument for functional characterization of the notable and newly discovered virus. Understanding of structure and composition of viruses has contributed to the evolution of molecular plant pathology. Therefore, this review provides extensive guidelines on the strategy to construct infectious clones of Begomovirus. Also, this technique’s impacts and benefits in controlling and understanding the Begomovirus infection will be discussed.
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Padilla R, Gaillard V, Le TN, Bellvert F, Chapulliot D, Nesme X, Dessaux Y, Vial L, Lavire C, Kerzaon I. Development and validation of a UHPLC-ESI-QTOF mass spectrometry method to analyze opines, plant biomarkers of crown gall or hairy root diseases. J Chromatogr B Analyt Technol Biomed Life Sci 2021; 1162:122458. [PMID: 33383499 DOI: 10.1016/j.jchromb.2020.122458] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 11/14/2020] [Accepted: 11/17/2020] [Indexed: 11/26/2022]
Abstract
Opines are low-molecular-weight metabolites specifically biosynthesized by agrobacteria-transformed plant cells when plants are struck by crown gall and hairy root diseases, which cause uncontrolled tissue overgrowth. Transferred DNA is sustainably incorporated into the genomes of the transformed plant cells, so that opines constitute a persistent biomarker of plant infection by pathogenic agrobacteria and can be targeted for crown gall/hairy root disease diagnosis. We developed a general, rapid, specific and sensitive analytical method for overall opine detection using ultra-high-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-MS-QTOF), with easy preparation of samples. Based on MS, MS/MS and chromatography data, the detection selectivity of a wide range of standard opines was validated in pure solution and in different plant extracts. The method was successfully used to detect different structural types of opines, including opines for which standard compounds are unavailable, in tumors or hairy roots induced by pathogenic strains. As the method can detect a wide range of opines in a single run, it represents a powerful tool for plant gall analysis and crown gall/hairy root disease diagnosis. Using an appropriate dilution of plant extract and a matrix-based calibration curve, the quantification ability of the method was validated for three opines belonging to different families (nopaline, octopine, mannopine), which were accurately quantified in plant tissue extracts.
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Affiliation(s)
- Rosa Padilla
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Vincent Gaillard
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Thao Nhi Le
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France; Université d'Orléans, CNRS, Institut de Chimie Organique et Analytique, F-45067 Orléans, France
| | - Floriant Bellvert
- Université de Toulouse, CNRS, INRAE, INSA, Laboratoire Ingénierie des Systèmes Biologiques et des Procédés, F-31077 Toulouse, France; MetaToul-MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, F-31077 Toulouse, France
| | - David Chapulliot
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Xavier Nesme
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Yves Dessaux
- Université Paris-Sud, Université Paris-Saclay, CNRS, CEA, Institut de Biologie Intégrative de la Cellule, F-91190 Gif-sur-Yvette, France
| | - Ludovic Vial
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Céline Lavire
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France
| | - Isabelle Kerzaon
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INRAE, VetAgro Sup, UMR Ecologie Microbienne, F-69622 Villeurbanne, France.
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De Saeger J, Park J, Chung HS, Hernalsteens JP, Van Lijsebettens M, Inzé D, Van Montagu M, Depuydt S. Agrobacterium strains and strain improvement: Present and outlook. Biotechnol Adv 2020; 53:107677. [PMID: 33290822 DOI: 10.1016/j.biotechadv.2020.107677] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 11/03/2020] [Accepted: 11/28/2020] [Indexed: 12/12/2022]
Abstract
Almost 40 years ago the first transgenic plant was generated through Agrobacterium tumefaciens-mediated transformation, which, until now, remains the method of choice for gene delivery into plants. Ever since, optimized Agrobacterium strains have been developed with additional (genetic) modifications that were mostly aimed at enhancing the transformation efficiency, although an optimized strain also exists that reduces unwanted plasmid recombination. As a result, a collection of very useful strains has been created to transform a wide variety of plant species, but has also led to a confusing Agrobacterium strain nomenclature. The latter is often misleading for choosing the best-suited strain for one's transformation purposes. To overcome this issue, we provide a complete overview of the strain classification. We also indicate different strain modifications and their purposes, as well as the obtained results with regard to the transformation process sensu largo. Furthermore, we propose additional improvements of the Agrobacterium-mediated transformation process and consider several worthwhile modifications, for instance, by circumventing a defense response in planta. In this regard, we will discuss pattern-triggered immunity, pathogen-associated molecular pattern detection, hormone homeostasis and signaling, and reactive oxygen species in relationship to Agrobacterium transformation. We will also explore alterations that increase agrobacterial transformation efficiency, reduce plasmid recombination, and improve biocontainment. Finally, we recommend the use of a modular system to best utilize the available knowledge for successful plant transformation.
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Affiliation(s)
- Jonas De Saeger
- Laboratory of Plant Growth Analysis, Ghent University Global Campus, Incheon 406-840, South Korea; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Jihae Park
- Laboratory of Plant Growth Analysis, Ghent University Global Campus, Incheon 406-840, South Korea; Department of Marine Sciences, Incheon National University, Incheon 406-840, South Korea
| | - Hoo Sun Chung
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | | | - Mieke Van Lijsebettens
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Dirk Inzé
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Marc Van Montagu
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium
| | - Stephen Depuydt
- Laboratory of Plant Growth Analysis, Ghent University Global Campus, Incheon 406-840, South Korea; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium.
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Thompson MA, Onyeziri MC, Fuqua C. Function and Regulation of Agrobacterium tumefaciens Cell Surface Structures that Promote Attachment. Curr Top Microbiol Immunol 2019; 418:143-184. [PMID: 29998422 PMCID: PMC6330146 DOI: 10.1007/82_2018_96] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Agrobacterium tumefaciens attaches stably to plant host tissues and abiotic surfaces. During pathogenesis, physical attachment to the site of infection is a prerequisite to infection and horizontal gene transfer to the plant. Virulent and avirulent strains may also attach to plant tissue in more benign plant associations, and as with other soil microbes, to soil surfaces in the terrestrial environment. Although most A. tumefaciens virulence functions are encoded on the tumor-inducing plasmid, genes that direct general surface attachment are chromosomally encoded, and thus this process is not obligatorily tied to virulence, but is a more fundamental capacity. Several different cellular structures are known or suspected to contribute to the attachment process. The flagella influence surface attachment primarily via their propulsive activity, but control of their rotation during the transition to the attached state may be quite complex. A. tumefaciens produces several pili, including the Tad-type Ctp pili, and several plasmid-borne conjugal pili encoded by the Ti and At plasmids, as well as the so-called T-pilus, involved in interkingdom horizontal gene transfer. The Ctp pili promote reversible interactions with surfaces, whereas the conjugal and T-pili drive horizontal gene transfer (HGT) interactions with other cells and tissues. The T-pilus is likely to contribute to physical association with plant tissues during DNA transfer to plants. A. tumefaciens can synthesize a variety of polysaccharides including cellulose, curdlan (β-1,3 glucan), β-1,2 glucan (cyclic and linear), succinoglycan, and a localized polysaccharide(s) that is confined to a single cellular pole and is called the unipolar polysaccharide (UPP). Lipopolysaccharides are also in the outer leaflet of the outer membrane. Cellulose and curdlan production can influence attachment under certain conditions. The UPP is required for stable attachment under a range of conditions and on abiotic and biotic surfaces. Other factors that have been reported to play a role in attachment include the elusive protein called rhicadhesin. The process of surface attachment is under extensive regulatory control and can be modulated by environmental conditions, as well as by direct responses to surface contact. Complex transcriptional and post-transcriptional control circuitry underlies much of the production and deployment of these attachment functions.
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Affiliation(s)
- Melene A Thompson
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | | | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
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Tang G, Li Q, Xing S, Li N, Tang Z, Yu L, Yan J, Li X, Luo L. The LsrB Protein Is Required for Agrobacterium tumefaciens Interaction with Host Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:951-961. [PMID: 29547354 DOI: 10.1094/mpmi-02-18-0041-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Agrobacterium tumefaciens infects and causes crown galls in dicot plants by transferring T-DNA from the Ti plasmid to the host plant via a type IV secretion system. This process requires appropriate environmental conditions, certain plant secretions, and bacterial regulators. In our previous work, a member of the LysR family of transcriptional regulators (LsrB) in Sinorhizobium meliloti was found to modulate its symbiotic interactions with the host plant alfalfa. However, the function of its homolog in A. tumefaciens remains unclear. In this study, we show that the LsrB protein of A. tumefaciens is required for efficient transformation of host plants. A lsrB deletion mutant of A. tumefaciens exhibits a number of defects, including in succinoglycan production, attachment, and resistance to oxidative stress and iron limitation. RNA-sequencing analysis indicated that 465 genes were significantly differentially expressed (upregulation of 162 genes and downregulation of 303 genes) in the mutant, compared with the wild-type strain, including those involved in succinoglycan production, iron transporter, and detoxification enzymes for oxidative stress. Moreover, expression of the lsrB gene from S. meliloti, Brucella abortus, or A. tumefaciens rescued the defects observed in the S. meliloti or A. tumefaciens lsrB deletion mutant. Our findings suggest that a conserved mechanism of LsrB function exists in symbiotic and pathogenic bacteria of the family Rhizobiaceae.
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Affiliation(s)
- Guirong Tang
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
- 2 School of Communication & Information Engineering, Shanghai University; and
| | - Qiong Li
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Shenghui Xing
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Ningning Li
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Zheng Tang
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Liangliang Yu
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Junhui Yan
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Xuan Li
- 3 Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Li Luo
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
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Golanowska M, Potrykus M, Motyka-Pomagruk A, Kabza M, Bacci G, Galardini M, Bazzicalupo M, Makalowska I, Smalla K, Mengoni A, Hugouvieux-Cotte-Pattat N, Lojkowska E. Comparison of Highly and Weakly Virulent Dickeya solani Strains, With a View on the Pangenome and Panregulon of This Species. Front Microbiol 2018; 9:1940. [PMID: 30233505 PMCID: PMC6127512 DOI: 10.3389/fmicb.2018.01940] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 07/31/2018] [Indexed: 11/30/2022] Open
Abstract
Bacteria belonging to the genera Dickeya and Pectobacterium are responsible for significant economic losses in a wide variety of crops and ornamentals. During last years, increasing losses in potato production have been attributed to the appearance of Dickeya solani. The D. solani strains investigated so far share genetic homogeneity, although different virulence levels were observed among strains of various origins. The purpose of this study was to investigate the genetic traits possibly related to the diverse virulence levels by means of comparative genomics. First, we developed a new genome assembly pipeline which allowed us to complete the D. solani genomes. Four de novo sequenced and ten publicly available genomes were used to identify the structure of the D. solani pangenome, in which 74.8 and 25.2% of genes were grouped into the core and dispensable genome, respectively. For D. solani panregulon analysis, we performed a binding site prediction for four transcription factors, namely CRP, KdgR, PecS and Fur, to detect the regulons of these virulence regulators. Most of the D. solani potential virulence factors were predicted to belong to the accessory regulons of CRP, KdgR, and PecS. Thus, some differences in gene expression could exist between D. solani strains. The comparison between a highly and a low virulent strain, IFB0099 and IFB0223, respectively, disclosed only small differences between their genomes but significant differences in the production of virulence factors like pectinases, cellulases and proteases, and in their mobility. The D. solani strains also diverge in the number and size of prophages present in their genomes. Another relevant difference is the disruption of the adhesin gene fhaB2 in the highly virulent strain. Strain IFB0223, which has a complete adhesin gene, is less mobile and less aggressive than IFB0099. This suggests that in this case, mobility rather than adherence is needed in order to trigger disease symptoms. This study highlights the utility of comparative genomics in predicting D. solani traits involved in the aggressiveness of this emerging plant pathogen.
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Affiliation(s)
- Malgorzata Golanowska
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Marta Potrykus
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Agata Motyka-Pomagruk
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Michal Kabza
- Department of Integrative Genomics, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Giovanni Bacci
- Department of Biology, University of Florence, Florence, Italy
| | - Marco Galardini
- EMBL, EBI, Wellcome Trust Genome Campus, Cambridge, United Kingdom
| | | | - Izabela Makalowska
- Department of Integrative Genomics, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Kornelia Smalla
- Department of Epidemiology and Pathogen Diagnostics, Julius Kühn-Institut - Federal Research Centre for Cultivated Plants, Braunschweig, Germany
| | - Alessio Mengoni
- Department of Biology, University of Florence, Florence, Italy
| | - Nicole Hugouvieux-Cotte-Pattat
- UMR5240 Microbiologie Adaptation et Pathogénie, Univ Lyon, CNRS, Univ Claude Bernard Lyon 1, INSA Lyon, Villeurbanne, France
| | - Ewa Lojkowska
- Department of Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
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González-Mula A, Lang J, Grandclément C, Naquin D, Ahmar M, Soulère L, Queneau Y, Dessaux Y, Faure D. Lifestyle of the biotroph Agrobacterium tumefaciens in the ecological niche constructed on its host plant. THE NEW PHYTOLOGIST 2018; 219:350-362. [PMID: 29701262 DOI: 10.1111/nph.15164] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 03/13/2018] [Indexed: 05/23/2023]
Abstract
Agrobacterium tumefaciens constructs an ecological niche in its host plant by transferring the T-DNA from its Ti plasmid into the host genome and by diverting the host metabolism. We combined transcriptomics and genetics for understanding the A. tumefaciens lifestyle when it colonizes Arabidopsis thaliana tumors. Transcriptomics highlighted: a transition from a motile to sessile behavior that mobilizes some master regulators (Hfq, CtrA, DivK and PleD); a remodeling of some cell surface components (O-antigen, succinoglucan, curdlan, att genes, putative fasciclin) and functions associated with plant defense (Ef-Tu and flagellin pathogen-associated molecular pattern-response and glycerol-3-phosphate and nitric oxide signaling); and an exploitation of a wide variety of host resources, including opines, amino acids, sugars, organic acids, phosphate, phosphorylated compounds, and iron. In addition, construction of transgenic A. thaliana lines expressing a lactonase enzyme showed that Ti plasmid transfer could escape host-mediated quorum-quenching. Finally, construction of knock-out mutants in A. tumefaciens showed that expression of some At plasmid genes seemed more costly than the selective advantage they would have conferred in tumor colonization. We provide the first overview of A. tumefaciens lifestyle in a plant tumor and reveal novel signaling and trophic interplays for investigating host-pathogen interactions.
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Affiliation(s)
- Almudena González-Mula
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Julien Lang
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Catherine Grandclément
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Delphine Naquin
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Mohammed Ahmar
- Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires (ICBMS), INSA-Lyon, Université Lyon 1, CNRS, CPE Lyon, ICBMS, UMR5246, INSA Lyon, Villeurbanne, F-69621, France
| | - Laurent Soulère
- Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires (ICBMS), INSA-Lyon, Université Lyon 1, CNRS, CPE Lyon, ICBMS, UMR5246, INSA Lyon, Villeurbanne, F-69621, France
| | - Yves Queneau
- Institut de Chimie et de Biochimie Moléculaires et Supramoléculaires (ICBMS), INSA-Lyon, Université Lyon 1, CNRS, CPE Lyon, ICBMS, UMR5246, INSA Lyon, Villeurbanne, F-69621, France
| | - Yves Dessaux
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
| | - Denis Faure
- Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, University Paris-Saclay, Gif-sur-Yvette, F-91190, France
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Effective removal of a range of Ti/Ri plasmids using a pBBR1-type vector having a repABC operon and a lux reporter system. Appl Microbiol Biotechnol 2018; 102:1823-1836. [PMID: 29318333 DOI: 10.1007/s00253-017-8721-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/09/2017] [Accepted: 12/15/2017] [Indexed: 10/18/2022]
Abstract
Ti and Ri plasmids of pathogenic Agrobacterium strains are stably maintained by the function of a repABC operon and have been classified into four incompatibility groups, namely, incRh1, incRh2, incRh3, and incRh4. Removal of these plasmids from their bacterial cells is an important step in determining strain-specific virulence characteristics and to construct strains useful for transformation. Here, we developed two powerful tools to improve this process. We first established a reporter system to detect the presence and absence of Ti/Ri plasmids in cells by using an acetosyringone (AS)-inducible promoter of the Ti2 small RNA and luxAB from Vibrio harveyi. This system distinguished a Ti/Ri plasmid-free cell colony among plasmid-harboring cell colonies by causing the latter colonies to emit light in response to AS. We then constructed new "Ti/Ri eviction plasmids," each of which carries a repABC from one of four Ti/Ri plasmids that belonged to incRh1, incRh2, incRh3, and incRh4 groups in the suicidal plasmid pK18mobsacB and in a broad-host-range pBBR1 vector. Introduction of the new eviction plasmids into Agrobacterium cells harboring the corresponding Ti/Ri plasmids led to Ti/Ri plasmid-free cells in every incRh group. The Ti/Ri eviction was more effective by plasmids with the pBBR1 backbone than by those with the pK18mobsacB backbone. Furthermore, the highly stable cryptic plasmid pAtC58 in A. tumefaciens C58 was effectively evicted by the introduction of a pBBR1 vector containing the repABC of pAtC58. These results indicate that the set of pBBR1-repABC plasmids is a powerful tool for the removal of stable rhizobial plasmids.
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Platt TG, Morton ER, Barton IS, Bever JD, Fuqua C. Ecological dynamics and complex interactions of Agrobacterium megaplasmids. FRONTIERS IN PLANT SCIENCE 2014; 5:635. [PMID: 25452760 PMCID: PMC4231840 DOI: 10.3389/fpls.2014.00635] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Accepted: 10/27/2014] [Indexed: 05/15/2023]
Abstract
As with many pathogenic bacteria, agrobacterial plant pathogens carry most of their virulence functions on a horizontally transmissible genetic element. The tumor-inducing (Ti) plasmid encodes the majority of virulence functions for the crown gall agent Agrobacterium tumefaciens. This includes the vir genes which drive genetic transformation of host cells and the catabolic genes needed to utilize the opines produced by infected plants. The Ti plasmid also encodes, an opine-dependent quorum sensing system that tightly regulates Ti plasmid copy number and its conjugal transfer to other agrobacteria. Many natural agrobacteria are avirulent, lacking the Ti plasmid. The burden of harboring the Ti plasmid depends on the environmental context. Away from diseased hosts, plasmid costs are low but the benefit of the plasmid is also absent. Consequently, plasmidless genotypes are favored. On infected plants the costs of the Ti plasmid can be very high, but balanced by the opine benefits, locally favoring plasmid bearing cells. Cheating derivatives which do not incur virulence costs but can benefit from opines are favored on infected plants and in most other environments, and these are frequently isolated from nature. Many agrobacteria also harbor an At plasmid which can stably coexist with a Ti plasmid. At plasmid genes are less well characterized but in general facilitate metabolic activities in the rhizosphere and bulk soil, such as the ability to breakdown plant exudates. Examination of A. tumefaciens C58, revealed that harboring its At plasmid is much more costly than harboring it's Ti plasmid, but conversely the At plasmid is extremely difficult to cure. The interactions between these co-resident plasmids are complex, and depend on environmental context. However, the presence of a Ti plasmid appears to mitigate At plasmid costs, consistent with the high frequency with which they are found together.
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Affiliation(s)
| | | | | | | | - Clay Fuqua
- Department of Biology, Indiana UniversityBloomington, IN, USA
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Matthysse AG. Attachment of Agrobacterium to plant surfaces. FRONTIERS IN PLANT SCIENCE 2014; 5:252. [PMID: 24926300 PMCID: PMC4046570 DOI: 10.3389/fpls.2014.00252] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 05/16/2014] [Indexed: 05/23/2023]
Abstract
Agrobacterium tumefaciens binds to the surfaces of inanimate objects, plants, and fungi. These bacteria are excellent colonizers of root surfaces. In addition, they also bind to soil particles and to the surface of artificial or man-made substances, such as polyesters and plastics. The mechanisms of attachment to these different surfaces have not been completely elucidated. At least two types of binding have been described unipolarpolysaccharide-dependent polar attachment and unipolar polysaccharide-independent attachment (both polar and lateral). The genes encoding the enzymes for the production of the former are located on the circular chromosome, while the genes involved in the latter have not been identified. The expression of both of these types of attachment is regulated in response to environmental signals. However, the signals to which they respond differ so that the two types of attachment are not necessarily expressed coordinately.
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Affiliation(s)
- Ann G. Matthysse
- *Correspondence: Ann G. Matthysse, Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA e-mail:
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Heindl JE, Wang Y, Heckel BC, Mohari B, Feirer N, Fuqua C. Mechanisms and regulation of surface interactions and biofilm formation in Agrobacterium. FRONTIERS IN PLANT SCIENCE 2014; 5:176. [PMID: 24834068 PMCID: PMC4018554 DOI: 10.3389/fpls.2014.00176] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 04/12/2014] [Indexed: 05/05/2023]
Abstract
For many pathogenic bacteria surface attachment is a required first step during host interactions. Attachment can proceed to invasion of host tissue or cells or to establishment of a multicellular bacterial community known as a biofilm. The transition from a unicellular, often motile, state to a sessile, multicellular, biofilm-associated state is one of the most important developmental decisions for bacteria. Agrobacterium tumefaciens genetically transforms plant cells by transfer and integration of a segment of plasmid-encoded transferred DNA (T-DNA) into the host genome, and has also been a valuable tool for plant geneticists. A. tumefaciens attaches to and forms a complex biofilm on a variety of biotic and abiotic substrates in vitro. Although rarely studied in situ, it is hypothesized that the biofilm state plays an important functional role in the ecology of this organism. Surface attachment, motility, and cell division are coordinated through a complex regulatory network that imparts an unexpected asymmetry to the A. tumefaciens life cycle. In this review, we describe the mechanisms by which A. tumefaciens associates with surfaces, and regulation of this process. We focus on the transition between flagellar-based motility and surface attachment, and on the composition, production, and secretion of multiple extracellular components that contribute to the biofilm matrix. Biofilm formation by A. tumefaciens is linked with virulence both mechanistically and through shared regulatory molecules. We detail our current understanding of these and other regulatory schemes, as well as the internal and external (environmental) cues mediating development of the biofilm state, including the second messenger cyclic-di-GMP, nutrient levels, and the role of the plant host in influencing attachment and biofilm formation. A. tumefaciens is an important model system contributing to our understanding of developmental transitions, bacterial cell biology, and biofilm formation.
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Affiliation(s)
| | | | | | | | | | - Clay Fuqua
- Department of Biology, Indiana University, BloomingtonIN, USA
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12
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Rudder S, Doohan F, Creevey CJ, Wendt T, Mullins E. Genome sequence of Ensifer adhaerens OV14 provides insights into its ability as a novel vector for the genetic transformation of plant genomes. BMC Genomics 2014; 15:268. [PMID: 24708309 PMCID: PMC4051167 DOI: 10.1186/1471-2164-15-268] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 03/19/2014] [Indexed: 02/19/2023] Open
Abstract
BACKGROUND Recently it has been shown that Ensifer adhaerens can be used as a plant transformation technology, transferring genes into several plant genomes when equipped with a Ti plasmid. For this study, we have sequenced the genome of Ensifer adhaerens OV14 (OV14) and compared it with those of Agrobacterium tumefaciens C58 (C58) and Sinorhizobium meliloti 1021 (1021); the latter of which has also demonstrated a capacity to genetically transform crop genomes, albeit at significantly reduced frequencies. RESULTS The 7.7 Mb OV14 genome comprises two chromosomes and two plasmids. All protein coding regions in the OV14 genome were functionally grouped based on an eggNOG database. No genes homologous to the A. tumefaciens Ti plasmid vir genes appeared to be present in the OV14 genome. Unexpectedly, OV14 and 1021 were found to possess homologs to chromosomal based genes cited as essential to A. tumefaciens T-DNA transfer. Of significance, genes that are non-essential but exert a positive influence on virulence and the ability to genetically transform host genomes were identified in OV14 but were absent from the 1021 genome. CONCLUSIONS This study reveals the presence of homologs to chromosomally based Agrobacterium genes that support T-DNA transfer within the genome of OV14 and other alphaproteobacteria. The sequencing and analysis of the OV14 genome increases our understanding of T-DNA transfer by non-Agrobacterium species and creates a platform for the continued improvement of Ensifer-mediated transformation (EMT).
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Affiliation(s)
- Steven Rudder
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona Doohan
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Christopher J Creevey
- Animal and Bioscience Research Department, Animal and Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland
- Current address: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3FL, UK
| | - Toni Wendt
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
- UCD Earth Institute and UCD School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
- Current address: Carlsberg Research Centre, Gamle Carlsberg Vej 4-10, 1799 Copenhagen V, Denmark
| | - Ewen Mullins
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
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Morton ER, Platt TG, Fuqua C, Bever JD. Non-additive costs and interactions alter the competitive dynamics of co-occurring ecologically distinct plasmids. Proc Biol Sci 2014; 281:20132173. [PMID: 24500159 PMCID: PMC3924060 DOI: 10.1098/rspb.2013.2173] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 01/07/2014] [Indexed: 11/12/2022] Open
Abstract
Plasmids play an important role in shaping bacterial evolution and adaptation to heterogeneous environments. As modular genetic elements that are often conjugative, the selective pressures that act on plasmid-borne genes are distinct from those that act on the chromosome. Many bacteria are co-infected by multiple plasmids that impart niche-specific phenotypes. Thus, in addition to host-plasmid dynamics, interactions between co-infecting plasmids are likely to be important drivers of plasmid population dynamics, evolution and ecology. Agrobacterium tumefaciens is a facultative plant pathogen that commonly harbours two distinct megaplasmids. Virulence depends on the presence of the tumour-inducing (Ti) plasmid, with benefits that are primarily restricted to the disease environment. Here, we demonstrate that a second megaplasmid, the At plasmid, confers a competitive advantage in the rhizosphere. To assess the individual and interactive costs of these plasmids, we generated four isogenic derivatives: plasmidless, pAt only, pTi only and pAtpTi, and performed pairwise competitions under carbon-limiting conditions. These studies reveal a low cost to the virulence plasmid when outside of the disease environment, and a strikingly high cost to the At plasmid. In addition, the costs of pAt and pTi in the same host were significantly lower than predicted based on single plasmid costs, signifying the first demonstration of non-additivity between naturally occurring co-resident plasmids. Based on these empirically demonstrated costs and benefits, we developed a resource-consumer model to generate predictions about the frequencies of these genotypes in relevant environments, showing that non-additivity between co-residing plasmids allows for their stable coexistence across environments.
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Affiliation(s)
- Elise R. Morton
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Morton ER, Merritt PM, Bever JD, Fuqua C. Large deletions in the pAtC58 megaplasmid of Agrobacterium tumefaciens can confer reduced carriage cost and increased expression of virulence genes. Genome Biol Evol 2013; 5:1353-64. [PMID: 23783172 PMCID: PMC3730347 DOI: 10.1093/gbe/evt095] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The accessory plasmid pAtC58 of the common laboratory strain of Agrobacterium tumefaciens confers numerous catabolic functions and has been proposed to play a role in virulence. Genomic sequencing of evolved laboratory strains of A. tumefaciens revealed the presence of multiple deletion events in the At plasmid, with reductions in plasmid size ranging from 25% to 30% (115–194 kb). Flanking both ends of the sites of these deletions is a short-nucleotide repeat sequence that is in a single copy in the deleted plasmids, characteristic of a phage- or transposon-mediated deletion event. This repeat sequence is widespread throughout the C58 genome, but concentrated on the At plasmid, suggesting its frequency to be nonrandom. In this study, we assess the prevalence of the larger of these deletions in multiple C58 derivatives and characterize its functional significance. We find that in addition to elevating virulence gene expression, this deletion is associated with a significantly reduced carriage cost to the cell. These observations are a clear demonstration of the dynamic nature of the bacterial genome and suggest a mechanism for genetic plasticity of these costly but otherwise stable plasmids. Additionally, this phenomenon could be the basis for some of the dramatic recombination events so ubiquitous within and among megaplasmids.
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15
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Lang J, Planamente S, Mondy S, Dessaux Y, Moréra S, Faure D. Concerted transfer of the virulence Ti plasmid and companion At plasmid in the Agrobacterium tumefaciens-induced plant tumour. Mol Microbiol 2013; 90:1178-89. [PMID: 24118167 DOI: 10.1111/mmi.12423] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2013] [Indexed: 01/28/2023]
Abstract
The plant pathogen Agrobacterium tumefaciens C58 harbours three independent type IV secretion (T4SS) machineries. T4SST-DNA promotes the transfer of the T-DNA to host plant cells, provoking tumour development and accumulation of opines such as nopaline and agrocinopines. T4SSpTi and T4SSpAt control the bacterial conjugation of the Ti and At plasmids respectively. Expression of T4SSpTi is controlled by the agrocinopine-responsive transcriptional repressor AccR. In this work, we compared the genome-wide transcriptional profile of the wild-type A. tumefaciens strain C58 with that of its accR KO-mutant to delineate the AccR regulon. In addition to the genes that encode agrocinopine catabolism and T4SSpTi , we found that AccR also regulated genes coding for nopaline catabolism and T4SSpAt . Further opine detection and conjugation assays confirmed the enhancement of nopaline consumption and At plasmid conjugation frequency in accR. Moreover, co-regulation of the T4SSpTi and T4SSpAt correlated with the co-transfer of the At and Ti plasmids both in vitro and in plant tumours. Finally, unlike T4SSpTi , T4SSpAt activation does not require quorum-sensing. Overall this study highlights the regulatory interplays between opines, At and Ti plasmids that contribute to a concerted dissemination of the two replicons in bacterial populations colonizing the plant tumour.
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Affiliation(s)
- Julien Lang
- Centre National de la Recherche Scientifique, Institut des Sciences du Végétal, UPR2355, 1, Avenue de la Terrasse, 91198, Gif-sur-Yvette, France
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16
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Ghedira R, De Buck S, Nolf J, Depicker A. The efficiency of Arabidopsis thaliana floral dip transformation is determined not only by the Agrobacterium strain used but also by the physiology and the ecotype of the dipped plant. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:823-32. [PMID: 23581821 DOI: 10.1094/mpmi-11-12-0267-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
To evaluate the chromosomal background of different Agrobacterium strains on floral dip transformation frequency, eight wild-type Agrobacterium strains, provided by Laboratorium voor Microbiologie Gent (LMG) and classified in different genomic groups, were compared with the commonly used Agrobacterium strains C58C1 Rif(r) (pMP90) and LBA4404 in Arabidopsis thaliana Columbia (Col-0) and C24 ecotypes. The C58C1 Rif(r) chromosomal background in combination with the pMP90 virulence plasmid showed high Col-0 floral dip transformation frequencies (0.76 to 1.57%). LMG201, which is genetically close to the Agrobacterium C58 strain, with the same virulence plasmid showed comparable or even higher transformation frequencies (1.22 to 2.28%), whereas the LBA4404 strain displayed reproducibly lower transformation frequencies (<0.2%). All other tested LMG Agrobacterium chromosomal backgrounds had transformation frequencies between those of the C58C1 Rif(r) (pMP90) and LBA4404 reference strains. None of the strains could transform the C24 ecotype with a frequency higher than 0.1%. Strikingly, all Arabidopsis Col-0 floral dip transformation experiments showed a high transformation variability from plant to plant (even more than 50-fold) within and across the performed biological repeats for all analyzed Agrobacterium strains. Therefore, the physiology of the plant and, probably, the availability of competent flowers to be transformed determine, to a large extent, floral dip transformation frequencies.
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Affiliation(s)
- Rim Ghedira
- Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
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17
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Lacroix B, Citovsky V. The roles of bacterial and host plant factors in Agrobacterium-mediated genetic transformation. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2013. [PMID: 24166430 DOI: 10.1387/ijdb.130199b1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The genetic transformation of plants mediated by Agrobacterium tumefaciens represents an essential tool for both fundamental and applied research in plant biology. For a successful infection, culminating in the integration of its transferred DNA (T-DNA) into the host genome, Agrobacterium relies on multiple interactions with host-plant factors. Extensive studies have unraveled many of such interactions at all major steps of the infection process: activation of the bacterial virulence genes, cell-cell contact and macromolecular translocation from Agrobacterium to host cell cytoplasm, intracellular transit of T-DNA and associated proteins (T-complex) to the host cell nucleus, disassembly of the T-complex, T-DNA integration, and expression of the transferred genes. During all these processes, Agrobacterium has evolved to control and even utilize several pathways of host-plant defense response. Studies of these Agrobacterium-host interactions substantially enhance our understanding of many fundamental cellular biological processes and allow improvements in the use of Agrobacterium as a gene transfer tool for biotechnology.
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Affiliation(s)
- Benoît Lacroix
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY, USA.
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18
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Wibberg D, Blom J, Jaenicke S, Kollin F, Rupp O, Scharf B, Schneiker-Bekel S, Sczcepanowski R, Goesmann A, Setubal JC, Schmitt R, Pühler A, Schlüter A. Complete genome sequencing of Agrobacterium sp. H13-3, the former Rhizobium lupini H13-3, reveals a tripartite genome consisting of a circular and a linear chromosome and an accessory plasmid but lacking a tumor-inducing Ti-plasmid. J Biotechnol 2011; 155:50-62. [DOI: 10.1016/j.jbiotec.2011.01.010] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 12/16/2010] [Accepted: 01/02/2011] [Indexed: 11/16/2022]
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19
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The integrity of the periplasmic domain of the VirA sensor kinase is critical for optimal coordination of the virulence signal response in Agrobacterium tumefaciens. J Bacteriol 2011; 193:1436-48. [PMID: 21216996 DOI: 10.1128/jb.01227-10] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The plant pathogen Agrobacterium tumefaciens responds to three main signals at the plant-bacterium interface: phenolics, such as acetosyringone (AS), monosaccharides, and acidic pH (∼5.5). These signals are transduced via the chromosomally encoded sugar binding protein ChvE and the Ti plasmid-encoded VirA/VirG two-component regulatory system, resulting in the transcriptional activation of the Ti plasmid virulence genes. Here, we present genetic and physical evidence that the periplasmic domain of VirA dimerizes independently of other parts of the protein, and we examine the effects of several engineered mutations in the periplasmic and transmembrane regions of VirA on vir-inducing capacity as indicated by AS sensitivity and maximal level of vir-inducing activity at saturating AS levels. The data indicate that helix-breaking mutations throughout the periplasmic domain of VirA or mutations that reposition the second transmembrane domain (TM2) of VirA relieve the periplasmic domain's repressive effects on the maximal activity of this kinase in response to phenolics, effects normally relieved only when ChvE, sugars, and low pH are also present. Such relief, however, does not sensitize VirA to low concentrations of phenolics, the other major effect of the ChvE-sugar and low pH signals. We further demonstrate that amino acid residues in a small Trg-like motif in the periplasmic domain of VirA are crucial for transmission of the ChvE-sugar signal to the cytoplasmic domain. These experiments provide evidence that small perturbations in the periplasmic domain of VirA can uncouple sugar-mediated changes in AS sensitivity from the sugar-mediated effects on maximal activity.
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20
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Tomlinson AD, Ramey-Hartung B, Day TW, Merritt PM, Fuqua C. Agrobacterium tumefaciens ExoR represses succinoglycan biosynthesis and is required for biofilm formation and motility. MICROBIOLOGY-SGM 2010; 156:2670-2681. [PMID: 20576688 PMCID: PMC3068688 DOI: 10.1099/mic.0.039032-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The ubiquitous plant pathogen Agrobacterium tumefaciens attaches efficiently to plant tissues and abiotic surfaces and can form complex biofilms. A genetic screen for mutants unable to form biofilms on PVC identified disruptions in a homologue of the exoR gene. ExoR is a predicted periplasmic protein, originally identified in Sinorhizobium meliloti, but widely conserved among alphaproteobacteria. Disruptions in the A. tumefaciens exoR gene result in severely compromised attachment to abiotic surfaces under static and flow conditions, and to plant tissues. These mutants are hypermucoid due to elevated production of the exopolysaccharide succinoglycan, via derepression of the exo genes that direct succinoglycan synthesis. In addition, exoR mutants have lost flagellar motility, do not synthesize detectable flagellin and are diminished in flagellar gene expression. The attachment deficiency is, however, complex and not solely attributable to succinoglycan overproduction or motility disruption. A. tumefaciens ExoR can function independently of the ChvG–ChvI two component system, implicated in ExoR-dependent regulation in S. meliloti. Mutations that suppress the exoR motility defect suggest a branched regulatory pathway controlling succinoglycan synthesis, motility and biofilm formation.
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Affiliation(s)
| | | | - Travis W Day
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Peter M Merritt
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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21
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Tomlinson AD, Fuqua C. Mechanisms and regulation of polar surface attachment in Agrobacterium tumefaciens. Curr Opin Microbiol 2009; 12:708-14. [PMID: 19879182 DOI: 10.1016/j.mib.2009.09.014] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 09/25/2009] [Indexed: 11/27/2022]
Abstract
Agrobacterium tumefaciens is a plant pathogen that transfers a segment of its own DNA into host plants to cause Crown Gall disease. The infection process requires intimate contact between the infecting bacteria and the host tissue. A. tumefaciens attaches efficiently to plant tissues and to abiotic surfaces, and can establish complex biofilms at colonization sites. The dominant mode of attachment is via a single pole in contact with the surface. Several different appendages, adhesins and adhesives play roles during attachment, and foster the transition from free-swimming to sessile growth. This polar surface interaction reflects a more fundamental cellular asymmetry in A. tumefaciens that influences and is congruent with its attached lifestyle.
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Recovery of nonpathogenic mutant bacteria from tumors caused by several Agrobacterium tumefaciens strains: a frequent event? Appl Environ Microbiol 2009; 75:6504-14. [PMID: 19700547 DOI: 10.1128/aem.01867-08] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have evaluated the interaction that bacterial genotypes and plant hosts have with the loss of pathogenicity in tumors, using seven Agrobacterium tumefaciens strains inoculated on 12 herbaceous and woody hosts. We performed a screening of the agrobacteria present inside the tumors, looking for nonpathogenic strains, and found a high variability of those strains in this niche. To verify the origin of the putative nonpathogenic mutant bacteria, we applied an efficient, reproducible, and specific randomly amplified polymorphic DNA analysis method. In contrast with previous studies, we recovered a very small percentage (0.01%) of nonpathogenic strains that can be considered true mutants. Of 5,419 agrobacterial isolates examined, 662 were nonpathogenic in tomato, although only 7 (from pepper and tomato tumors induced by two A. tumefaciens strains) could be considered to derive from the inoculated strain. Six mutants were affected in the transferred DNA (T-DNA) region; one of them contained IS426 inserted into the iaaM gene, whereas the whole T-DNA region was apparently deleted in three other mutants, and the virulence of the remaining two mutants was fully restored with the T-DNA genes as well. The plasmid profile was altered in six of the mutants, with changes in the size of the Ti plasmid or other plasmids and/or the acquisition of new plasmids. Our results also suggest that the frequent occurrence of nonpathogenic clones in the tumors is probably due to the preferential growth of nonpathogenic agrobacteria, of either endophytic or environmental origin, but different from the bacterial strain inducing the tumor.
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The BlcC (AttM) lactonase of Agrobacterium tumefaciens does not quench the quorum-sensing system that regulates Ti plasmid conjugative transfer. J Bacteriol 2008; 191:1320-9. [PMID: 19011037 DOI: 10.1128/jb.01304-08] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The conjugative transfer of Agrobacterium plasmids is controlled by a quorum-sensing system consisting of TraR and its acyl-homoserine lactone (HSL) ligand. The acyl-HSL is essential for the TraR-mediated activation of the Ti plasmid Tra genes. Strains A6 and C58 of Agrobacterium tumefaciens produce a lactonase, BlcC (AttM), that can degrade the quormone, leading some to conclude that the enzyme quenches the quorum-sensing system. We tested this hypothesis by examining the effects of the mutation, induction, or mutational derepression of blcC on the accumulation of acyl-HSL and on the conjugative competence of strain C58. The induction of blc resulted in an 8- to 10-fold decrease in levels of extracellular acyl-HSL but in only a twofold decrease in intracellular quormone levels, a measure of the amount of active intracellular TraR. The induction or mutational derepression of blc as well as a null mutation in blcC had no significant effect on the induction of or continued transfer of pTiC58 from donors in any stage of growth, including stationary phase. In matings performed in developing tumors, wild-type C58 transferred the Ti plasmid to recipients, yielding transconjugants by 14 to 21 days following infection. blcC-null donors yielded transconjugants 1 week earlier, but by the following week, transconjugants were recovered at numbers indistinguishable from those of the wild type. Donors mutationally derepressed for blcC yielded transconjugants in planta at numbers 10-fold lower than those for the wild type at weeks 2 and 3, but by week 4, the two donors showed no difference in recoverable transconjugants. We conclude that BlcC has no biologically significant effect on Ti plasmid transfer or its regulatory system.
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Matthysse AG, Jaeckel P, Jeter C. attG and attC mutations of Agrobacterium tumefaciens are dominant negative mutations that block attachment and virulence. Can J Microbiol 2008; 54:241-7. [PMID: 18388996 DOI: 10.1139/w08-005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The cryptic plasmid (pAT) of Agrobacterium tumefaciens was not required for virulence or attachment to plant surfaces. However, mutations in the attC and attG genes located on pAT caused the bacteria to become avirulent and non-attaching on tomato, carrot, and Bryophyllum daigremontiana. This was the case whether the mutation was in the copy of the genes located on pAT or whether it was carried in a second copy of the attA-G operon located on a plasmid in cells that contained a wild-type copy of pAT. Thus attC and attG mutations are dominant negative mutations. The mechanism by which these mutations block attachment and virulence is unknown.
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Affiliation(s)
- Ann G Matthysse
- Department of Biology, University of North Carolina, Coker Hall, Chapel Hill, NC 27599-3280, USA.
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26
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Abstract
Agrobacterium tumefaciens encodes a single NAD+-dependent DNA ligase and six putative ATP-dependent ligases. Two of the ligases are homologs of LigD, a bacterial enzyme that catalyzes end-healing and end-sealing steps during nonhomologous end joining (NHEJ). Agrobacterium LigD1 and AtuLigD2 are composed of a central ligase domain fused to a C-terminal polymerase-like (POL) domain and an N-terminal 3′-phosphoesterase (PE) module. Both LigD proteins seal DNA nicks, albeit inefficiently. The LigD2 POL domain adds ribonucleotides or deoxyribonucleotides to a DNA primer-template, with rNTPs being the preferred substrates. The LigD1 POL domain has no detectable polymerase activity. The PE domains catalyze metal-dependent phosphodiesterase and phosphomonoesterase reactions at a primer-template with a 3′-terminal diribonucleotide to yield a primer-template with a monoribonucleotide 3′-OH end. The PE domains also have a 3′-phosphatase activity on an all-DNA primer-template that yields a 3′-OH DNA end. Agrobacterium ligases C2 and C3 are composed of a minimal ligase core domain, analogous to Mycobacterium LigC (another NHEJ ligase), and they display feeble nick-sealing activity. Ligation at DNA double-strand breaks in vitro by LigD2, LigC2 and LigC3 is stimulated by bacterial Ku, consistent with their proposed function in NHEJ.
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Affiliation(s)
| | - Stewart Shuman
- *To whom correspondence should be addressed. 212 639 7145212 717 3623
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McCullen CA, Binns AN. Agrobacterium tumefaciens and plant cell interactions and activities required for interkingdom macromolecular transfer. Annu Rev Cell Dev Biol 2006; 22:101-27. [PMID: 16709150 DOI: 10.1146/annurev.cellbio.22.011105.102022] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Host recognition and macromolecular transfer of virulence-mediating effectors represent critical steps in the successful transformation of plant cells by Agrobacterium tumefaciens. This review focuses on bacterial and plant-encoded components that interact to mediate these two processes. First, we examine the means by which Agrobacterium recognizes the host, via both diffusible plant-derived chemicals and cell-cell contact, with emphasis on the mechanisms by which multiple host signals are recognized and activate the virulence process. Second, we characterize the recognition and transfer of protein and protein-DNA complexes through the bacterial and plant cell membrane and wall barriers, emphasizing the central role of a type IV secretion system-the VirB complex-in this process.
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Affiliation(s)
- Colleen A McCullen
- Department of Biology and Plant Sciences Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018, USA
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Penalver CGN, Cantet F, Morin D, Haras D, Vorholt JA. A plasmid-borne truncated luxI homolog controls quorum-sensing systems and extracellular carbohydrate production in Methylobacterium extorquens AM1. J Bacteriol 2006; 188:7321-4. [PMID: 17015673 PMCID: PMC1636247 DOI: 10.1128/jb.00649-06] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A cryptic plasmid of Methylobacterium extorquens AM1 was found to encode tslI, a truncated luxI homolog. tslI was shown to be expressed and to control transcription of the acyl-homoserine lactone (HSL) synthase gene msaI and thus, indirectly, acyl-HSL production. In addition, tslI was found to positively regulate extracellular polysaccharide production.
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Affiliation(s)
- Carlos G Nieto Penalver
- Institute of Microbiology, Swiss Federal Institute of Technology Zurich, ETH Hönggerberg, Zurich, Switzerland
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Su S, Stephens BB, Alexandre G, Farrand SK. Lon protease of the α-proteobacterium Agrobacterium tumefaciens is required for normal growth, cellular morphology and full virulence. Microbiology (Reading) 2006; 152:1197-1207. [PMID: 16549682 DOI: 10.1099/mic.0.28657-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ATP-dependent Lon (La) protease is ubiquitous in nature and regulates a diverse set of physiological responses in bacteria. In this paper alonmutant of theα-proteobacteriumAgrobacterium tumefaciensC58 has been characterized. Unlikelonmutants ofEscherichia coli, thelonmutant ofA. tumefaciensgrows very slowly, is not filamentous and exhibits normal resistance to UV irradiation. The mutant retains motility and chemotaxis, produces apparently normal amounts of exopolysacchride, but displays severe defects in cell morphology, with 80 % of the mutant cells appearing Y-shaped. Lon protease ofA. tumefaciensshares high homology with its counterparts inE. coliand inSinorhizobium meliloti, and functionally complements anE. coli lonmutant for defects in morphology and RcsA-mediated regulation of capsular polysaccharide production. Mutations at sites of LonAtcorresponding to the ATP-binding site and the active site serine of theE. coliLon protease abolish complementation of phenotypes of theA. tumefaciensandE. coli lonmutants. The nucleotide sequence upstream ofA. tumefaciens loncontains an element similar to the consensusσ32heat-shock promoter ofE. coli. Northern and Western blot analyses indicated that expression oflonis induced by elevated temperature, albeit to a much lower level than that ofgroEL. Thelonmutant is highly attenuated for virulence, suggesting that Lon may be required for the proper expression, assembly or function of the VirB/D4-mediated T-DNA transfer system.
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Affiliation(s)
- Shengchang Su
- Department of Microbiology, University of Illinois at Urbana-Champaign, B103 CLSL, 601 South Goodwin Avenue, Urbana, IL 61801, USA
| | - Bonnie B Stephens
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Gladys Alexandre
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Stephen K Farrand
- Department of Microbiology, University of Illinois at Urbana-Champaign, B103 CLSL, 601 South Goodwin Avenue, Urbana, IL 61801, USA
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Broothaerts W, Mitchell HJ, Weir B, Kaines S, Smith LMA, Yang W, Mayer JE, Roa-Rodríguez C, Jefferson RA. Gene transfer to plants by diverse species of bacteria. Nature 2005; 433:629-33. [PMID: 15703747 DOI: 10.1038/nature03309] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2004] [Accepted: 12/29/2004] [Indexed: 11/09/2022]
Abstract
Agrobacterium is widely considered to be the only bacterial genus capable of transferring genes to plants. When suitably modified, Agrobacterium has become the most effective vector for gene transfer in plant biotechnology. However, the complexity of the patent landscape has created both real and perceived obstacles to the effective use of this technology for agricultural improvements by many public and private organizations worldwide. Here we show that several species of bacteria outside the Agrobacterium genus can be modified to mediate gene transfer to a number of diverse plants. These plant-associated symbiotic bacteria were made competent for gene transfer by acquisition of both a disarmed Ti plasmid and a suitable binary vector. This alternative to Agrobacterium-mediated technology for crop improvement, in addition to affording a versatile 'open source' platform for plant biotechnology, may lead to new uses of natural bacteria-plant interactions to achieve plant transformation.
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Affiliation(s)
- Wim Broothaerts
- CAMBIA, Research Centre of Charles Sturt University, G.P.O. Box 3200, Canberra, ACT 2601, Australia
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Carlier A, Chevrot R, Dessaux Y, Faure D. The assimilation of gamma-butyrolactone in Agrobacterium tumefaciens C58 interferes with the accumulation of the N-acyl-homoserine lactone signal. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2004; 17:951-7. [PMID: 15384485 DOI: 10.1094/mpmi.2004.17.9.951] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Agrobacterium tumefaciens C58 communicates using N-acyl-homoserine lactones (acyl-HSL) and contains two lactonase-encoding genes, attM and aiiB, the products of which are capable of inactivating the acyl-HSL signal. In A. tumefaciens A6, the expression of the attKLM operon is controlled by the transcriptional repressor encoded by an adjacent gene, attJ. An attJ::Tn5 mutant does not accumulate acyl-HSL because of the constitutive expression of the lactonase AttM, the activity of which inactivates acyl-HSL. In this work, the attKLM operon of A. tumefaciens C58 was shown to be involved in an assimilative pathway of gamma-butyrolactone (GBL), gamma-hydroxybutyrate (GHB), and succinate semialdehyde (SSA), in which AttM and AttL are key enzymes for GBL and GHB assimilation. The expression of the attKLM promoter was activated in the presence of GBL, GHB, and SSA. Under these conditions, A. tumefaciens C58 did not accumulate the acyl-HSL that it naturally synthesizes, and also became able to inactivate exogenous acyl-HSL signals. Therefore, in A. tumefaciens C58, the assimilative pathway of gamma-butyrolactone interferes with the acyl-HSL signaling.
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Affiliation(s)
- Aurélien Carlier
- Institut des Sciences du Végétal, UPR2355, Centre National de la Recherche Scientifique, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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Danhorn T, Hentzer M, Givskov M, Parsek MR, Fuqua C. Phosphorus limitation enhances biofilm formation of the plant pathogen Agrobacterium tumefaciens through the PhoR-PhoB regulatory system. J Bacteriol 2004; 186:4492-501. [PMID: 15231781 PMCID: PMC438617 DOI: 10.1128/jb.186.14.4492-4501.2004] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Accepted: 02/26/2004] [Indexed: 11/20/2022] Open
Abstract
The plant pathogen Agrobacterium tumefaciens forms architecturally complex biofilms on inert surfaces. Adherence of A. tumefaciens C58 was significantly enhanced under phosphate limitation compared to phosphate-replete conditions, despite slower overall growth under low-phosphate conditions. Replacement of Pi with sn-glycerol-3-phosphate and 2-aminoethylphosphonate yielded similar results. The increase in surface interactions under phosphate limitation was observed in both static culture and continuous-culture flow cells. Statistical analysis of confocal micrographs obtained from the flow cell biofilms revealed that phosphate limitation increased both the overall attached biomass and the surface coverage, whereas the maximum thickness of the biofilm was not affected. Functions encoded on the two large plasmids of A. tumefaciens C58, pTiC58 and pAtC58, were not required for the observed phosphate effect. The phosphate concentration at which increased attachment was observed triggered the phosphate limitation response, controlled in many bacteria by the two-component regulatory system PhoR-PhoB. The A. tumefaciens phoB and phoR orthologues could only be disrupted in the presence of plasmid-borne copies of the genes, suggesting that this regulatory system might be essential. Expression of the A. tumefaciens phoB gene from a tightly regulated inducible promoter, however, correlated with the amount of biofilm under both phosphate-limiting and nonlimiting conditions, demonstrating that components of the Pho regulon influence A. tumefaciens surface interactions.
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Affiliation(s)
- Thomas Danhorn
- Department of Biology, 1001 E. 3rd St., Jordan Hall 142, Indiana University, Bloomington, IN 47405-1847, USA
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Tzfira T, Citovsky V. The Agrobacterium-plant cell interaction. Taking biology lessons from a bug. PLANT PHYSIOLOGY 2003; 133:943-7. [PMID: 14612580 PMCID: PMC1540338 DOI: 10.1104/pp.103.032821] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
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