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Agarwal V, Stubits R, Nassrullah Z, Dillon MM. Pangenome insights into the diversification and disease specificity of worldwide Xanthomonas outbreaks. Front Microbiol 2023; 14:1213261. [PMID: 37476668 PMCID: PMC10356107 DOI: 10.3389/fmicb.2023.1213261] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/15/2023] [Indexed: 07/22/2023] Open
Abstract
The bacterial genus Xanthomonas is responsible for disease outbreaks in several hundred plant species, many of them economically important crops. In the era of next-generation sequencing, thousands of strains from this genus have now been sequenced as part of isolated studies that focus on outbreak characterization, host range, diversity, and virulence factor identification. However, these data have not been synthesized and we lack a comprehensive phylogeny for the genus, with some species designations in public databases still relying on phenotypic similarities and representative sequence typing. The extent of genetic cohesiveness among Xanthomonas strains, the distribution of virulence factors across strains, and the impact of evolutionary history on host range across the genus are also poorly understood. In this study, we present a pangenome analysis of 1,910 diverse Xanthomonas genomes, highlighting their evolutionary relationships, the distribution of virulence-associated genes across strains, and rates of horizontal gene transfer. We find a number of broadly conserved classes of virulence factors and considerable diversity in the Type 3 Secretion Systems (T3SSs) and Type 3 Secreted Effector (T3SE) repertoires of different Xanthomonas species. We also use these data to re-assign incorrectly classified strains to phylogenetically informed species designations and find evidence of both monophyletic host specificity and convergent evolution of phylogenetically distant strains to the same host. Finally, we explore the role of recombination in maintaining genetic cohesion within the Xanthomonas genus as a result of both ancestral and recent recombination events. Understanding the evolutionary history of Xanthomonas species and the relationship of key virulence factors with host-specificity provides valuable insight into the mechanisms through which Xanthomonas species shift between hosts and will enable us to develop more robust resistance strategies against these highly virulent pathogens.
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Affiliation(s)
- Viplav Agarwal
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Rachel Stubits
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Zain Nassrullah
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Marcus M. Dillon
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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2
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Li M, Bao Y, Li Y, Akbar S, Wu G, Du J, Wen R, Chen B, Zhang M. Comparative genome analysis unravels pathogenicity of Xanthomonas albilineans causing sugarcane leaf scald disease. BMC Genomics 2022; 23:671. [PMID: 36162999 PMCID: PMC9513982 DOI: 10.1186/s12864-022-08900-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/19/2022] [Indexed: 11/28/2022] Open
Abstract
Background Xanthomonas is a genus of gram-negative bacterium containing more than 35 species. Among these pathogenic species, Xanthomonas albilineans (Xal) is of global interest, responsible for leaf scald disease in sugarcane. Another notable Xanthomonas species is Xanthomonas sachari (Xsa), a sugarcane-associated agent of chlorotic streak disease. Result The virulence of 24 Xanthomonas strains was evaluated by disease index (DI) and Area Under Disease Progress Curve (AUDPC) in the susceptible inoculated plants (GT 46) and clustered into three groups of five highly potent, seven mild virulent, and twelve weak virulent strains. The highly potent strain (X. albilineans, Xal JG43) and its weak virulent related strain (X. sacchari, Xsa DD13) were sequenced, assembled, and annotated in the circular genomes. The genomic size of JG43 was smaller than that of DD13. Both strains (JG43 and DD13) lacked a Type III secretory system (T3SS) and T6SS. However, JG43 possessed Salmonella pathogenicity island-1 (SPI-1). More pathogen-host interaction (PHI) genes and virulent factors in 17 genomic islands (GIs) were detected in JG43, among which six were related to pathogenicity. Albicidin and a two-component system associated with virulence were also detected in JG43. Furthermore, 23 Xanthomonas strains were sequenced and classified into three categories based on Single Nucleotide Polymorphism (SNP) mutation loci and pathogenicity, using JG43 as a reference genome. Transitions were dominant SNP mutations, while structural variation (SV) is frequent intrachromosomal rearrangement (ITX). Two essential genes (rpfC/rpfG) of the two-component system and another gene related to SNP were mutated to understand their virulence effect. The mutation of rpfG resulted in a decrease in pathogenicity. Conclusion These findings revealed virulence of 24 Xanthomonas strains and variations by 23 Xanthomonas strains. We sequenced, assembled, and annotated the circular genomes of Xal JG43 and Xsa DD13, identifying diversity detected by pathogenic factors and systems. Furthermore, complete genomic sequences and sequenced data will provide a theoretical basis for identifying pathogenic factors responsible for sugarcane leaf scald disease. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08900-2.
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Affiliation(s)
- MeiLin Li
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - YiXue Bao
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - YiSha Li
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - Sehrish Akbar
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - GuangYue Wu
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - JinXia Du
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - Ronghui Wen
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - Baoshan Chen
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - MuQing Zhang
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China.
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3
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Wang J, Luo Y, Gu Y, Wei HL. Characterization of the SPI-1 Type III Secretion System in Pseudomonas fluorescens 2P24. Front Microbiol 2021; 12:749037. [PMID: 34621260 PMCID: PMC8490769 DOI: 10.3389/fmicb.2021.749037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/31/2021] [Indexed: 12/04/2022] Open
Abstract
Pseudomonas fluorescens 2P24 is a plant growth-promoting rhizobacterium (PGPR) isolated from wheat take-all decline soil. Genomic analysis of strain 2P24 revealed the presence of a complete SPI-1 type III secretion system (T3SS) gene cluster on the chromosome with an organization and orientation similar to the SPI-1 T3SS gene clusters of Salmonella enterica and P. kilonensis F113. Phylogenetic analysis revealed that the SPI-1 T3SS gene cluster of strain 2P24 might be obtained from Salmonella and Shigella by horizontal gene transfer. Two transcriptional regulator homologs of HilA and InvF were found from the SPI-1 T3SS gene cluster of strain 2P24. HilA regulated the expression of the structural genes positively, such as invG, sipB, sipD, prgI, and prgK. Prediction of transcriptional binding sites and RNA-seq analysis revealed 14 genes were up-regulated by InvF in strain 2P24. Exploring potential roles of SPI-1 T3SS revealed that it was not associated with motility. However, 2P24ΔinvF reduced resistance against Fusarium graminearum significantly. 2P24ΔhilA enhanced formation of biofilm significantly at 48 h. All three mutants 2P24ΔhilA, 2P24ΔinvF, and 2P24ΔinvE-C reduced the chemotactic responses to glucose significantly. Finally, the determination of SPI-1 mutants to trigger innate immunity in Nicotiana benthamiana showed that 2P24ΔinvE-C reduced the ability to induce the production of reactive oxygen species compared with the wild type strain 2P24.
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Affiliation(s)
- Jing Wang
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Yuan Luo
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Yilin Gu
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Hai-Lei Wei
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
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4
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Secrete or perish: The role of secretion systems in Xanthomonas biology. Comput Struct Biotechnol J 2020; 19:279-302. [PMID: 33425257 PMCID: PMC7777525 DOI: 10.1016/j.csbj.2020.12.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/13/2020] [Accepted: 12/13/2020] [Indexed: 12/22/2022] Open
Abstract
Bacteria of the Xanthomonas genus are mainly phytopathogens of a large variety of crops of economic importance worldwide. Xanthomonas spp. rely on an arsenal of protein effectors, toxins and adhesins to adapt to the environment, compete with other microorganisms and colonize plant hosts, often causing disease. These protein effectors are mainly delivered to their targets by the action of bacterial secretion systems, dedicated multiprotein complexes that translocate proteins to the extracellular environment or directly into eukaryotic and prokaryotic cells. Type I to type VI secretion systems have been identified in Xanthomonas genomes. Recent studies have unravelled the diverse roles played by the distinct types of secretion systems in adaptation and virulence in xanthomonads, unveiling new aspects of their biology. In addition, genome sequence information from a wide range of Xanthomonas species and pathovars have become available recently, uncovering a heterogeneous distribution of the distinct families of secretion systems within the genus. In this review, we describe the architecture and mode of action of bacterial type I to type VI secretion systems and the distribution and functions associated with these important nanoweapons within the Xanthomonas genus.
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Doblas-Ibáñez P, Deng K, Vasquez MF, Giese L, Cobine PA, Kolkman JM, King H, Jamann TM, Balint-Kurti P, De La Fuente L, Nelson RJ, Mackey D, Smith LG. Dominant, Heritable Resistance to Stewart's Wilt in Maize Is Associated with an Enhanced Vascular Defense Response to Infection with Pantoea stewartii. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1581-1597. [PMID: 31657672 DOI: 10.1094/mpmi-05-19-0129-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Vascular wilt bacteria such as Pantoea stewartii, the causal agent of Stewart's bacterial wilt of maize (SW), are destructive pathogens that are difficult to control. These bacteria colonize the xylem, where they form biofilms that block sap flow leading to characteristic wilting symptoms. Heritable forms of SW resistance exist and are used in maize breeding programs but the underlying genes and mechanisms are mostly unknown. Here, we show that seedlings of maize inbred lines with pan1 mutations are highly resistant to SW. However, current evidence suggests that other genes introgressed along with pan1 are responsible for resistance. Genomic analyses of pan1 lines were used to identify candidate resistance genes. In-depth comparison of P. stewartii interaction with susceptible and resistant maize lines revealed an enhanced vascular defense response in pan1 lines characterized by accumulation of electron-dense materials in xylem conduits visible by electron microscopy. We propose that this vascular defense response restricts P. stewartii spread through the vasculature, reducing both systemic bacterial colonization of the xylem network and consequent wilting. Though apparently unrelated to the resistance phenotype of pan1 lines, we also demonstrate that the effector WtsE is essential for P. stewartii xylem dissemination, show evidence for a nutritional immunity response to P. stewartii that alters xylem sap composition, and present the first analysis of maize transcriptional responses to P. stewartii infection.
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Affiliation(s)
- Paula Doblas-Ibáñez
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Kaiyue Deng
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Miguel F Vasquez
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Laura Giese
- Department of Horticulture and Crop Sciences, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Paul A Cobine
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, U.S.A
| | - Judith M Kolkman
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
| | - Helen King
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
| | - Tiffany M Jamann
- Department of Crop Sciences, University of Illinois Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Peter Balint-Kurti
- United States Department of Agriculture-Agricultural Research Service, Plant Science Research Unit, Raleigh, NC 27695, U.S.A. and Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, U.S.A
| | | | - Rebecca J Nelson
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, U.S.A
| | - David Mackey
- Department of Horticulture and Crop Sciences, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Laurie G Smith
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA 92093, U.S.A
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Shah SMA, Haq F, Ma W, Xu X, Wang S, Xu Z, Zou L, Zhu B, Chen G. Tal1 NXtc01 in Xanthomonas translucens pv. cerealis Contributes to Virulence in Bacterial Leaf Streak of Wheat. Front Microbiol 2019; 10:2040. [PMID: 31551976 PMCID: PMC6737349 DOI: 10.3389/fmicb.2019.02040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 08/19/2019] [Indexed: 12/21/2022] Open
Abstract
Xanthomonas translucens pv. cerealis (Xtc) causes bacterial leaf streak (BLS) of important cereal crops, including wheat (Triticum aestivum) and barley (Hordeum vulgare). Transcription activator-like effectors (TALEs) play vital roles in many plant diseases caused by Xanthomonas spp., however, TALEs have not been previously characterized in Xtc. In this study, the whole genome of NXtc01, a virulent strain of Xtc from Xinjiang, China, was sequenced and compared with genomes of other Xanthomonas spp. Xtc NXtc01 consists of a single 4,622,298 bp chromosome that encodes 4,004 genes. Alignment of the NXtc01 sequence with the draft genome of Xtc strain CFBP 2541 (United States) revealed a single giant inversion and differences in the location of two tal genes, which were designated tal1 and tal2. In NXtc01, both tal genes are located on the chromosome, whereas tal2 is plasmid-encoded in CFBP 2541. The repeat variable diresidues (RVDs) at the 12th and 13th sites within Tal2 repeat units were identical in both strains, whereas Tal1 showed differences in the third RVD. Xtc NXtc01 and CFBP 2541 encoded 35 and 33 non-TALE type III effectors (T3Es), respectively. tal1, tal2, and tal-free deletion mutants of Xtc NXtc01 were constructed and evaluated for virulence. The tal1 and tal-free deletion mutants were impaired with respect to symptom development and growth in wheat, suggesting that tal1 is a virulence factor in NXtc01. This was confirmed in gain-of-function experiments that showed the introduction of tal1, but not tal2, restored virulence to the tal-free mutant. Furthermore, we generated a hrcC deletion mutant of NXtc01; the hrcC mutant was non-pathogenic on wheat and unable to elicit a hypersensitive response in the non-host Nicotiana benthamiana. Our data provide a platform for exploring the roles of both TALEs and non-TALEs in promoting BLS on wheat.
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Affiliation(s)
- Syed Mashab Ali Shah
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Fazal Haq
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Wenxiu Ma
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Xiameng Xu
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Sai Wang
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Zhengyin Xu
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Lifang Zou
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Bo Zhu
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Gongyou Chen
- School of Agriculture and Biology/State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
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7
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Merda D, Briand M, Bosis E, Rousseau C, Portier P, Barret M, Jacques MA, Fischer-Le Saux M. Ancestral acquisitions, gene flow and multiple evolutionary trajectories of the type three secretion system and effectors in Xanthomonas plant pathogens. Mol Ecol 2017; 26:5939-5952. [PMID: 28869687 PMCID: PMC7168496 DOI: 10.1111/mec.14343] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 08/03/2017] [Accepted: 08/05/2017] [Indexed: 12/13/2022]
Abstract
Deciphering the evolutionary history and transmission patterns of virulence determinants is necessary to understand the emergence of novel pathogens. The main virulence determinant of most pathogenic proteobacteria is the type three secretion system (T3SS). The Xanthomonas genus includes bacteria responsible for numerous epidemics in agroecosystems worldwide and represents a major threat to plant health. The main virulence factor of Xanthomonas is the Hrp2 family T3SS; however, this system is not conserved in all strains and it has not been previously determined whether the distribution of T3SS in this bacterial genus has resulted from losses or independent acquisitions. Based on comparative genomics of 82 genome sequences representing the diversity of the genus, we have inferred three ancestral acquisitions of the Hrp2 cluster during Xanthomonas evolution followed by subsequent losses in some commensal strains and re‐acquisition in some species. While mutation was the main force driving polymorphism at the gene level, interspecies homologous recombination of large fragments expanding through several genes shaped Hrp2 cluster polymorphism. Horizontal gene transfer of the entire Hrp2 cluster also occurred. A reduced core effectome composed of xopF1, xopM, avrBs2 and xopR was identified that may allow commensal strains overcoming plant basal immunity. In contrast, stepwise accumulation of numerous type 3 effector genes was shown in successful pathogens responsible for epidemics. Our data suggest that capacity to intimately interact with plants through T3SS would be an ancestral trait of xanthomonads. Since its acquisition, T3SS has experienced a highly dynamic evolutionary history characterized by intense gene flux between species that may reflect its role in host adaptation.
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Affiliation(s)
- Déborah Merda
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, Beaucouzé, France
| | - Martial Briand
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, Beaucouzé, France
| | - Eran Bosis
- Department of Biotechnology Engineering, ORT Braude College, Karmiel, Israel
| | - Céline Rousseau
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, Beaucouzé, France
| | - Perrine Portier
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, Beaucouzé, France
| | - Matthieu Barret
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, Beaucouzé, France
| | - Marie-Agnès Jacques
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, Beaucouzé, France
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8
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Klein JA, Dave BM, Raphenya AR, McArthur AG, Knodler LA. Functional relatedness in the Inv/Mxi-Spa type III secretion system family. Mol Microbiol 2017; 103:973-991. [PMID: 27997726 DOI: 10.1111/mmi.13602] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2016] [Indexed: 01/06/2023]
Abstract
Type III Secretion Systems (T3SSs) are structurally conserved nanomachines that span the inner and outer bacterial membranes, and via a protruding needle complex contact host cell membranes and deliver type III effector proteins. T3SS are phylogenetically divided into several families based on structural basal body components. Here we have studied the evolutionary and functional conservation of four T3SS proteins from the Inv/Mxi-Spa family: a cytosolic chaperone, two hydrophobic translocators that form a plasma membrane-integral pore, and the hydrophilic 'tip complex' translocator that connects the T3SS needle to the translocon pore. Salmonella enterica serovar Typhimurium (S. Typhimurium), a common cause of food-borne gastroenteritis, possesses two T3SSs, one belonging to the Inv/Mxi-Spa family. We used invasion-deficient S. Typhimurium mutants as surrogates for expression of translocator orthologs identified from an extensive phylogenetic analysis, and type III effector translocation and host cell invasion as a readout for complementation efficiency, and identified several Inv/Mxi-Spa orthologs that can functionally substitute for the S. Typhimurium chaperone and translocator proteins. Functional complementation correlates with amino acid sequence identity between orthologs, but varies considerably between the four proteins. This is the first in-depth survey of the functional interchangeability of Inv/Mxi-Spa T3SS proteins acting directly at the host-pathogen interface.
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Affiliation(s)
- Jessica A Klein
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA
| | - Biren M Dave
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Amogelang R Raphenya
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Andrew G McArthur
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Leigh A Knodler
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA
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9
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Aritua V, Harrison J, Sapp M, Buruchara R, Smith J, Studholme DJ. Genome sequencing reveals a new lineage associated with lablab bean and genetic exchange between Xanthomonas axonopodis pv. phaseoli and Xanthomonas fuscans subsp. fuscans. Front Microbiol 2015; 6:1080. [PMID: 26500625 PMCID: PMC4595841 DOI: 10.3389/fmicb.2015.01080] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 09/22/2015] [Indexed: 11/13/2022] Open
Abstract
Common bacterial blight is a devastating seed-borne disease of common beans that also occurs on other legume species including lablab and Lima beans. We sequenced and analyzed the genomes of 26 strains of Xanthomonas axonopodis pv. phaseoli and X. fuscans subsp. fuscans, the causative agents of this disease, collected over four decades and six continents. This revealed considerable genetic variation within both taxa, encompassing both single-nucleotide variants and differences in gene content, that could be exploited for tracking pathogen spread. The bacterial strain from Lima bean fell within the previously described Genetic Lineage 1, along with the pathovar type strain (NCPPB 3035). The strains from lablab represent a new, previously unknown genetic lineage closely related to strains of X. axonopodis pv. glycines. Finally, we identified more than 100 genes that appear to have been recently acquired by Xanthomonas axonopodis pv. phaseoli from X. fuscans subsp. fuscans.
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Affiliation(s)
- Valente Aritua
- International Center for Tropical Agriculture Kampala, Uganda
| | | | | | - Robin Buruchara
- Africa Regional Office, International Center for Tropical Agriculture, Consultative Group for International Agricultural Research (CGIAR) Nairobi, Kenya
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10
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Pieretti I, Cociancich S, Bolot S, Carrère S, Morisset A, Rott P, Royer M. Full Genome Sequence Analysis of Two Isolates Reveals a Novel Xanthomonas Species Close to the Sugarcane Pathogen Xanthomonas albilineans. Genes (Basel) 2015; 6:714-33. [PMID: 26213974 PMCID: PMC4584326 DOI: 10.3390/genes6030714] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/03/2015] [Accepted: 07/14/2015] [Indexed: 12/28/2022] Open
Abstract
Xanthomonas albilineans is the bacterium responsible for leaf scald, a lethal disease of sugarcane. Within the Xanthomonas genus, X. albilineans exhibits distinctive genomic characteristics including the presence of significant genome erosion, a non-ribosomal peptide synthesis (NRPS) locus involved in albicidin biosynthesis, and a type 3 secretion system (T3SS) of the Salmonella pathogenicity island-1 (SPI-1) family. We sequenced two X. albilineans-like strains isolated from unusual environments, i.e., from dew droplets on sugarcane leaves and from the wild grass Paspalum dilatatum, and compared these genomes sequences with those of two strains of X. albilineans and three of Xanthomonas sacchari. Average nucleotide identity (ANI) and multi-locus sequence analysis (MLSA) showed that both X. albilineans-like strains belong to a new species close to X. albilineans that we have named "Xanthomonas pseudalbilineans". X. albilineans and "X. pseudalbilineans" share many genomic features including (i) the lack of genes encoding a hypersensitive response and pathogenicity type 3 secretion system (Hrp-T3SS), and (ii) genome erosion that probably occurred in a common progenitor of both species. Our comparative analyses also revealed specific genomic features that may help X. albilineans interact with sugarcane, e.g., a PglA endoglucanase, three TonB-dependent transporters and a glycogen metabolism gene cluster. Other specific genomic features found in the "X. pseudalbilineans" genome may contribute to its fitness and specific ecological niche.
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Affiliation(s)
- Isabelle Pieretti
- CIRAD UMR BGPI, TA A-54/K, Campus International de Baillarguet, F-34398 Montpellier Cedex 5, France.
| | - Stéphane Cociancich
- CIRAD UMR BGPI, TA A-54/K, Campus International de Baillarguet, F-34398 Montpellier Cedex 5, France.
| | - Stéphanie Bolot
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, 24 Chemin de Borde Rouge-Auzeville CS52627, F-31326 Castanet Tolosan Cedex, France.
- CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, 24 Chemin de Borde Rouge-Auzeville CS52627, F-31326 Castanet Tolosan Cedex, France.
| | - Sébastien Carrère
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, 24 Chemin de Borde Rouge-Auzeville CS52627, F-31326 Castanet Tolosan Cedex, France.
- CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, 24 Chemin de Borde Rouge-Auzeville CS52627, F-31326 Castanet Tolosan Cedex, France.
| | - Alexandre Morisset
- CIRAD UMR BGPI, TA A-54/K, Campus International de Baillarguet, F-34398 Montpellier Cedex 5, France.
| | - Philippe Rott
- CIRAD UMR BGPI, TA A-54/K, Campus International de Baillarguet, F-34398 Montpellier Cedex 5, France.
| | - Monique Royer
- CIRAD UMR BGPI, TA A-54/K, Campus International de Baillarguet, F-34398 Montpellier Cedex 5, France.
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Pieretti I, Pesic A, Petras D, Royer M, Süssmuth RD, Cociancich S. What makes Xanthomonas albilineans unique amongst xanthomonads? FRONTIERS IN PLANT SCIENCE 2015; 6:289. [PMID: 25964795 PMCID: PMC4408752 DOI: 10.3389/fpls.2015.00289] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/09/2015] [Indexed: 06/04/2023]
Abstract
Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. Compared to other species of Xanthomonas, X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy. Its genome, which has experienced significant erosion, has unique genomic features. It lacks two loci required for pathogenicity in other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis and the Hrp-T3SS (hypersensitive response and pathogenicity-type three secretion system) gene clusters. Instead, X. albilineans harbors in its genome an SPI-1 (Salmonella pathogenicity island-1) T3SS gene cluster usually found in animal pathogens. X. albilineans produces a potent DNA gyrase inhibitor called albicidin, which blocks chloroplast differentiation, resulting in the characteristic white foliar stripe symptoms. The antibacterial activity of albicidin also confers on X. albilineans a competitive advantage against rival bacteria during sugarcane colonization. Recent chemical studies have uncovered the unique structure of albicidin and allowed us to partially elucidate its fascinating biosynthesis apparatus, which involves an enigmatic hybrid PKS/NRPS (polyketide synthase/non-ribosomal peptide synthetase) machinery.
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Affiliation(s)
| | - Alexander Pesic
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
| | - Daniel Petras
- Institut für Chemie, Technische Universität Berlin, Berlin, Germany
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Mensi I, Vernerey MS, Gargani D, Nicole M, Rott P. Breaking dogmas: the plant vascular pathogen Xanthomonas albilineans is able to invade non-vascular tissues despite its reduced genome. Open Biol 2014; 4:130116. [PMID: 24522883 PMCID: PMC3938051 DOI: 10.1098/rsob.130116] [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: 07/19/2013] [Accepted: 01/20/2014] [Indexed: 12/13/2022] Open
Abstract
Xanthomonas albilineans, the causal agent of sugarcane leaf scald, is missing the Hrp type III secretion system that is used by many Gram-negative bacteria to colonize their host. Until now, this pathogen was considered as strictly limited to the xylem of sugarcane. We used confocal laser scanning microscopy, immunocytochemistry and transmission electron microscopy (TEM) to investigate the localization of X. albilineans in diseased sugarcane. Sugarcane plants were inoculated with strains of the pathogen labelled with a green fluorescent protein. Confocal microscopy observations of symptomatic leaves confirmed the presence of the pathogen in the protoxylem and metaxylem; however, X. albilineans was also observed in phloem, parenchyma and bulliform cells of the infected leaves. Similarly, vascular bundles of infected sugarcane stalks were invaded by X. albilineans. Surprisingly, the pathogen was also observed in apparently intact storage cells of the stalk and in intercellular spaces between these cells. Most of these observations made by confocal microscopy were confirmed by TEM. The pathogen exits the xylem following cell wall and middle lamellae degradation, thus creating openings to reach parenchyma cells. This is the first description of a plant pathogenic vascular bacterium invading apparently intact non-vascular plant tissues and multiplying in parenchyma cells.
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Affiliation(s)
- Imène Mensi
- CIRAD, UMR BGPI, TA A-54/K, Montpellier Cedex 5 34398, France
| | | | - Daniel Gargani
- CIRAD, UMR BGPI, TA A-54/K, Montpellier Cedex 5 34398, France
| | - Michel Nicole
- IRD, UMR RPB, BP 64501, Montpellier Cedex 5 34394, France
| | - Philippe Rott
- CIRAD, UMR BGPI, TA A-54/K, Montpellier Cedex 5 34398, France
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13
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Wulff NA, Zhang S, Setubal JC, Almeida NF, Martins EC, Harakava R, Kumar D, Rangel LT, Foissac X, Bové JM, Gabriel DW. The complete genome sequence of 'Candidatus Liberibacter americanus', associated with Citrus huanglongbing. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:163-76. [PMID: 24200077 DOI: 10.1094/mpmi-09-13-0292-r] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Liberibacter spp. form a Rhizobiaceae clade of phloem-limited pathogens of limited host range. Two obligately parasitic species have been sequenced: 'Candidatus Liberibacter asiaticus', which causes citrus huanglongbing (HLB) worldwide, and 'Ca. L. solanacearum', which causes potato "zebra chip" disease. A third (proposed) species, Liberibacter crescens, was isolated from mountain papaya, grown in axenic culture, and sequenced. In an effort to identify common host determinants, the complete genomic DNA sequence of a second HLB species, 'Ca. L. americanus' strain 'São Paulo' was determined. The circular genome of 1,195,201 bp had an average 31.12% GC content and 983 predicted protein encoding genes, 800 (81.4%) of which had a predicted function. There were 658 genes common to all sequenced Liberibacter spp. and only 8 genes common to 'Ca. L. americanus' and 'Ca. L. asiaticus' but not found in 'Ca. L. solanacearum'. Surprisingly, most of the lipopolysaccharide biosynthetic genes were missing from the 'Ca. L. americanus' genome, as well as OmpA and a key regulator of flagellin, all indicating a 'Ca. L. americanus' strategy of avoiding production of major pathogen-associated molecular patterns present in 'Ca. L. asiaticus' and 'Ca. L. solanacearum'. As with 'Ca. L. asiaticus', one of two 'Ca. L. americanus' prophages replicated as an excision plasmid and carried potential lysogenic conversion genes that appeared fragmentary or degenerated in 'Ca. L. solanacearum'.
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14
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Tampakaki AP. Commonalities and differences of T3SSs in rhizobia and plant pathogenic bacteria. FRONTIERS IN PLANT SCIENCE 2014; 5:114. [PMID: 24723933 PMCID: PMC3973906 DOI: 10.3389/fpls.2014.00114] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 03/11/2014] [Indexed: 05/19/2023]
Abstract
Plant pathogenic bacteria and rhizobia infect higher plants albeit the interactions with their hosts are principally distinct and lead to completely different phenotypic outcomes, either pathogenic or mutualistic, respectively. Bacterial protein delivery to plant host plays an essential role in determining the phenotypic outcome of plant-bacteria interactions. The involvement of type III secretion systems (T3SSs) in mediating animal- and plant-pathogen interactions was discovered in the mid-80's and is now recognized as a multiprotein nanomachine dedicated to trans-kingdom movement of effector proteins. The discovery of T3SS in bacteria with symbiotic lifestyles broadened its role beyond virulence. In most T3SS-positive bacterial pathogens, virulence is largely dependent on functional T3SSs, while in rhizobia the system is dispensable for nodulation and can affect positively or negatively the mutualistic associations with their hosts. This review focuses on recent comparative genome analyses in plant pathogens and rhizobia that uncovered similarities and variations among T3SSs in their genetic organization, regulatory networks and type III secreted proteins and discusses the evolutionary adaptations of T3SSs and type III secreted proteins that might account for the distinguishable phenotypes and host range characteristics of plant pathogens and symbionts.
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Affiliation(s)
- Anastasia P. Tampakaki
- *Correspondence: Anastasia P. Tampakaki, Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, Iera Odos 75, Votanikos, 11855, Athens, Greece e-mail:
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15
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Egan F, Barret M, O’Gara F. The SPI-1-like Type III secretion system: more roles than you think. FRONTIERS IN PLANT SCIENCE 2014; 5:34. [PMID: 24575107 PMCID: PMC3921676 DOI: 10.3389/fpls.2014.00034] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 01/25/2014] [Indexed: 05/05/2023]
Abstract
The type III secretion system (T3SS) is a protein delivery system which is involved in a wide spectrum of interactions, from mutualism to pathogenesis, between Gram negative bacteria and various eukaryotes, including plants, fungi, protozoa and mammals. Various phylogenetic families of the T3SS have been described, including the Salmonella Pathogenicity Island 1 family (SPI-1). The SPI-1 T3SS was initially associated with the virulence of enteric pathogens, but is actually found in a diverse array of bacterial species, where it can play roles in processes as different as symbiotic interactions with insects and colonization of plants. We review the multiple roles of the SPI-1 T3SS and discuss both how these discoveries are changing our perception of the SPI-1 family and what impacts this has on our understanding of the specialization of the T3SS in general.
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Affiliation(s)
- Frank Egan
- BIOMERIT Research Centre, School of Microbiology, University College CorkCork, Ireland
| | - Matthieu Barret
- UMR1345 Institut de Recherche en Horticulture et Semences, Institut National de la Recherche AgronomiqueBeaucouzé, France
- UMR1345 Institut de Recherches en Horticulture et SemencesAgrocampus Ouest, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherches en Horticulture et Semences, SFR4207 QUASAVBeaucouzé, France
| | - Fergal O’Gara
- BIOMERIT Research Centre, School of Microbiology, University College CorkCork, Ireland
- School of Biomedical Sciences, Curtin UniversityPerth, WA, Australia
- *Correspondence: Fergal O’Gara, BIOMERIT Research Centre, School of Microbiology, University College Cork, Cork, Ireland e-mail:
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16
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Fleites LA, Mensi I, Gargani D, Zhang S, Rott P, Gabriel DW. Xanthomonas albilineans OmpA1 appears to be functionally modular and both the OMC and C-like domains are necessary for leaf scald disease of sugarcane. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:1200-1210. [PMID: 23758144 DOI: 10.1094/mpmi-01-13-0002-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Several EZ-Tn5 insertions in gene locus XALc_0557 (OmpA1) of the sugarcane leaf scald pathogen Xanthomonas albilineans XaFL07-1 were previously found to strongly affect pathogenicity and endophytic stalk colonization. XALc_0557 has a predicted OmpA N-terminal outer membrane channel (OMC) domain and an OmpA C-like domain. Further analysis of mutant M468, with an EZ-Tn5 insertion in the upstream OMC domain coding region, revealed impaired epiphytic and endophytic leaf survival, impaired resistance to sodium dodecyl sulfate (SDS), structural defects in the outer membrane (OM), and hyperproduction of OM vesicles. Cloned full-length XALc_0557 complemented M468 for all phenotypes tested, including pathogenicity, resistance to SDS, and ability to survive both endophytically and epiphytically. Another construct, pCT47.3, which expressed only the C-like domain of XALc_0557, restored resistance to SDS in M468 but failed to complement any other mutant phenotype, indicating that the C-like domain functioned independently of the OMC domain to help maintain OM integrity. pCT47.3 also complemented pathogenicity, resistance to SDS, and stalk colonization in mutant M1152, which carries an EZ-Tn5 insert in the C-like coding region, indicating that both predicted domains are modular and necessary but neither is sufficient for X. albilineans pathogenicity, endophytic survival in, and epiphytic survival on sugarcane.
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17
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Barret M, Egan F, Moynihan J, Morrissey JP, Lesouhaitier O, O'Gara F. Characterization of the SPI-1 and Rsp type three secretion systems in Pseudomonas fluorescens F113. ENVIRONMENTAL MICROBIOLOGY REPORTS 2013; 5:377-86. [PMID: 23754718 DOI: 10.1111/1758-2229.12039] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 01/10/2013] [Indexed: 05/21/2023]
Abstract
Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) isolated from the sugar beet rhizosphere. The recent annotation of the F113 genome sequence has revealed that this strain encodes a wide array of secretion systems, including two complete type three secretion systems (T3SSs) belonging to the Hrp1 and SPI-1 families. While Hrp1 T3SSs are frequently encoded in other P. fluorescens strains, the presence of a SPI-1 T3SS in a plant-beneficial bacterial strain was unexpected. In this work, the genetic organization and expression of these two T3SS loci have been analysed by a combination of transcriptional reporter fusions and transcriptome analyses. Overexpression of two transcriptional activators has shown a number of genes encoding putative T3 effectors. In addition, the influence of these two T3SSs during the interaction of P. fluorescens F113 with some bacterial predators was also assessed. Our data revealed that the transcriptional activator hilA is induced by amoeba and that the SPI-1 T3SS could potentially be involved in resistance to amoeboid grazing.
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Affiliation(s)
- Matthieu Barret
- BIOMERIT Research Centre, University College Cork, Cork, Ireland
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18
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Rott P, Fleites LA, Mensi I, Sheppard L, Daugrois JH, Dow JM, Gabriel DW. The RpfCG two-component system negatively regulates the colonization of sugar cane stalks by Xanthomonas albilineans. MICROBIOLOGY-SGM 2013; 159:1149-1159. [PMID: 23538716 DOI: 10.1099/mic.0.065748-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The genome of Xanthomonas albilineans, the causal agent of sugar cane leaf scald, carries a gene cluster encoding a predicted quorum sensing system that is highly related to the diffusible signalling factor (DSF) systems of the plant pathogens Xylella fastidiosa and Xanthomonas campestris. In these latter pathogens, a cluster of regulation of pathogenicity factors (rpf) genes encodes the DSF system and is involved in control of various cellular processes. Mutation of Xanthomonas albilineans rpfF, encoding a predicted DSF synthase, in Florida strain XaFL07-1 resulted in a small reduction of disease severity (DS). Single-knockout mutations of rpfC and rpfG (encoding a predicted DSF sensor and regulator, respectively) had no effect on DS or swimming motility of the pathogen. However, capacity of the pathogen to cause disease was slightly reduced and swimming motility was severely affected when rpfG and rpfC were both deleted. Similar results were obtained when the entire rpfGCF region was deleted. Surprisingly, when the pathogen was mutated in rpfG or rpfC (single or double mutations) it was able to colonize sugar cane spatially more efficiently than the wild-type. Mutation in rpfF alone did not affect the degree of spatial invasion. We conclude that the DSF signal contributes to symptom expression but not to invasion of sugar cane stalks by Xanthomonas albilineans strain XaFL07-1, which is mainly controlled by the RpfCG two-component system.
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Affiliation(s)
- Philippe Rott
- University of Florida, Department of Plant Pathology, Gainesville 32611, Florida, USA
- CIRAD, UMR BGPI, F-34398 Montpellier, France
| | - Laura A Fleites
- University of Florida, Department of Plant Pathology, Gainesville 32611, Florida, USA
| | - Imène Mensi
- CIRAD, UMR BGPI, F-34398 Montpellier, France
| | | | | | - J Maxwell Dow
- Department of Microbiology, Biosciences Institute, University College Cork, Cork, Ireland
| | - Dean W Gabriel
- University of Florida, Department of Plant Pathology, Gainesville 32611, Florida, USA
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Pieretti I, Royer M, Barbe V, Carrere S, Koebnik R, Couloux A, Darrasse A, Gouzy J, Jacques MA, Lauber E, Manceau C, Mangenot S, Poussier S, Segurens B, Szurek B, Verdier V, Arlat M, Gabriel DW, Rott P, Cociancich S. Genomic insights into strategies used by Xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels. BMC Genomics 2012; 13:658. [PMID: 23171051 PMCID: PMC3542200 DOI: 10.1186/1471-2164-13-658] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 11/18/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA gyrase inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa-another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH), genomic features of two strains differing in pathogenicity. RESULTS Comparative genomic analyses showed that most of the known pathogenicity factors from other Xanthomonas species are conserved in X. albilineans, with the notable absence of two major determinants of the "artillery" of other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis gene cluster, and the type III secretion system Hrp (hypersensitive response and pathogenicity). Genomic features specific to X. albilineans that may contribute to specific adaptation of this pathogen to sugarcane xylem vessels were also revealed. SSH experiments led to the identification of 20 genes common to three highly pathogenic strains but missing in a less pathogenic strain. These 20 genes, which include four ABC transporter genes, a methyl-accepting chemotaxis protein gene and an oxidoreductase gene, could play a key role in pathogenicity. With the exception of hypothetical proteins revealed by our comparative genomic analyses and SSH experiments, no genes potentially involved in any offensive or counter-defensive mechanism specific to X. albilineans were identified, supposing that X. albilineans has a reduced artillery compared to other pathogenic Xanthomonas species. Particular attention has therefore been given to genomic features specific to X. albilineans making it more capable of evading sugarcane surveillance systems or resisting sugarcane defense systems. CONCLUSIONS This study confirms that X. albilineans is a highly distinctive species within the genus Xanthomonas, and opens new perpectives towards a greater understanding of the pathogenicity of this destructive sugarcane pathogen.
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Affiliation(s)
| | - Monique Royer
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
| | - Valérie Barbe
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | | | - Ralf Koebnik
- IRD, UMR RPB, F-34394 Montpellier Cedex 5, France
| | - Arnaud Couloux
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | | | - Jérôme Gouzy
- INRA, UMR LIPM, F-31326 Castanet-Tolosan Cedex France
| | | | | | | | - Sophie Mangenot
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | - Stéphane Poussier
- Université de la Réunion, UMR PVBMT, F-97715 Saint-Denis La Réunion, France
| | - Béatrice Segurens
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | - Boris Szurek
- IRD, UMR RPB, F-34394 Montpellier Cedex 5, France
| | | | - Matthieu Arlat
- Université Paul Sabatier, UMR LIPM, F-31326 Castanet-Tolosan Cedex France
| | - Dean W Gabriel
- University of Florida, Plant Pathology Department, Gainesville FL 32605 USA
| | - Philippe Rott
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
| | - Stéphane Cociancich
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
- UMR BGPI, Campus International de Baillarguet, TA A-54/K, F-34398 Montpellier Cedex 5, France
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20
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Abby SS, Rocha EPC. The non-flagellar type III secretion system evolved from the bacterial flagellum and diversified into host-cell adapted systems. PLoS Genet 2012; 8:e1002983. [PMID: 23028376 PMCID: PMC3459982 DOI: 10.1371/journal.pgen.1002983] [Citation(s) in RCA: 200] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 08/09/2012] [Indexed: 12/20/2022] Open
Abstract
Type 3 secretion systems (T3SSs) are essential components of two complex bacterial machineries: the flagellum, which drives cell motility, and the non-flagellar T3SS (NF-T3SS), which delivers effectors into eukaryotic cells. Yet the origin, specialization, and diversification of these machineries remained unclear. We developed computational tools to identify homologous components of the two systems and to discriminate between them. Our analysis of >1,000 genomes identified 921 T3SSs, including 222 NF-T3SSs. Phylogenomic and comparative analyses of these systems argue that the NF-T3SS arose from an exaptation of the flagellum, i.e. the recruitment of part of the flagellum structure for the evolution of the new protein delivery function. This reconstructed chronology of the exaptation process proceeded in at least two steps. An intermediate ancestral form of NF-T3SS, whose descendants still exist in Myxococcales, lacked elements that are essential for motility and included a subset of NF-T3SS features. We argue that this ancestral version was involved in protein translocation. A second major step in the evolution of NF-T3SSs occurred via recruitment of secretins to the NF-T3SS, an event that occurred at least three times from different systems. In rhizobiales, a partial homologous gene replacement of the secretin resulted in two genes of complementary function. Acquisition of a secretin was followed by the rapid adaptation of the resulting NF-T3SSs to multiple, distinct eukaryotic cell envelopes where they became key in parasitic and mutualistic associations between prokaryotes and eukaryotes. Our work elucidates major steps of the evolutionary scenario leading to extant NF-T3SSs. It demonstrates how molecular evolution can convert one complex molecular machine into a second, equally complex machine by successive deletions, innovations, and recruitment from other molecular systems.
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Affiliation(s)
- Sophie S Abby
- Département Génomes et Génétique, Institut Pasteur, Microbial Evolutionary Genomics, Paris, France.
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21
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Lindeberg M. Genome-enabled perspectives on the composition, evolution, and expression of virulence determinants in bacterial plant pathogens. ANNUAL REVIEW OF PHYTOPATHOLOGY 2012; 50:111-132. [PMID: 22559066 DOI: 10.1146/annurev-phyto-081211-173022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Genome sequence analyses of bacterial plant pathogens are revealing important insights into the molecular determinants of pathogenicity and, through transcript characterization, responses to environmental conditions, evidence for small RNAs, and validation of uncharacterized genes. Genome comparison sheds further light on the processes impacting pathogen evolution and differences in gene repertoire among isolates contributing to niche specialization. Information derived from pathogen genome analysis is providing tools for use in diagnosis and interference with host-pathogen interactions for the purpose of disease control. However, the existing information infrastructure fails to adequately integrate the increasing numbers of sequence data sets, bioinformatic analyses, and experimental characterization, as required for effective systems-level analysis. Enhanced standardization of data formats at the point of publication is proposed as a possible solution.
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Affiliation(s)
- Magdalen Lindeberg
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York 14853, USA.
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22
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Studholme DJ, Wasukira A, Paszkiewicz K, Aritua V, Thwaites R, Smith J, Grant M. Draft Genome Sequences of Xanthomonas sacchari and Two Banana-Associated Xanthomonads Reveal Insights into the Xanthomonas Group 1 Clade. Genes (Basel) 2011; 2:1050-65. [PMID: 24710305 PMCID: PMC3927605 DOI: 10.3390/genes2041050] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 11/04/2011] [Accepted: 11/21/2011] [Indexed: 12/25/2022] Open
Abstract
We present draft genome sequences for three strains of Xanthomonas species, each of which was associated with banana plants (Musa species) but is not closely related to the previously sequenced banana-pathogen Xanthomonas campestris pathovar musacearum. Strain NCPPB4393 had been deposited as Xanthomonas campestris pathovar musacearum but in fact falls within the species Xanthomonas sacchari. Strain NCPPB1132 is more distantly related to Xanthomonas sacchari whilst strain NCPPB 1131 grouped in a distinct species-level clade related to X. sacchari, along with strains from ginger, rice, cotton and sugarcane. These three newly sequenced strains share many genomic features with the previously sequenced Xanthomonas albilineans, for example possessing an unsual metE allele and lacking the Hrp type III secretion system. However, they are distinct from Xanthomonas albilineans in many respects, for example showing little evidence of genome reduction. They also lack the SPI-1 type III secretion system found in Xanthomonas albilineans. Unlike X. albilineans, all three strains possess a gum gene cluster. The data reported here provide the first genome-wide survey of non-Hrp Xanthomonas species other than Xanthomonas albilineans, which is an atypical member of this group. We hope that the availability of complete sequence data for this group of organisms is the first step towards understanding their interactions with plants and identifying potential virulence factors.
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Affiliation(s)
- David J Studholme
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
| | - Arthur Wasukira
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
| | - Konrad Paszkiewicz
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
| | - Valente Aritua
- National Crops Resources Research Institute (NaCRRI), P.O. Box 7084, Kampala, Uganda.
| | - Richard Thwaites
- The Food and Environment Research Agency, Sand Hutton, York, YO41 1LZ, UK.
| | - Julian Smith
- The Food and Environment Research Agency, Sand Hutton, York, YO41 1LZ, UK.
| | - Murray Grant
- Department of Biosciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
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Rott P, Fleites L, Marlow G, Royer M, Gabriel DW. Identification of new candidate pathogenicity factors in the xylem-invading pathogen Xanthomonas albilineans by transposon mutagenesis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:594-605. [PMID: 21190440 DOI: 10.1094/mpmi-07-10-0156] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Xanthomonas albilineans is a xylem-invading pathogen that produces the toxin albicidin that blocks chloroplast differentiation, resulting in disease symptoms of sugarcane leaf scald. In contrast to other xanthomonads, X. albilineans does not possess a hypersensitive response and pathogenicity type III secretion system and does not produce xanthan gum. Albicidin is the only previously known pathogenicity factor in X. albilineans, yet albicidin-deficient mutant strains are still able to efficiently colonize sugarcane. To identify additional host adaptation or pathogenicity factors, sugarcane 'CP80-1743' was inoculated with 1,216 independently derived Tn5 insertions in X. albilineans XaFL07-1 from Florida. Sixty-one Tn5 mutants were affected in development of leaf symptoms or in stalk colonization. The Tn5 insertion sites of these mutants were determined and the interrupted genes were identified using the recently available genomic DNA sequence of X. albilineans GPE PC73 from Guadeloupe. Several pathogenicity-related loci that were not previously reported in Xanthomonas spp. were identified, including loci encoding hypothetical proteins, a membrane fusion protein conferring resistance to novobiocin, transport proteins, TonB-dependent outer-membrane transporters, and an OmpA family outer-membrane protein.
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Affiliation(s)
- Philippe Rott
- UMR BGPI, CIRAD, TA A-54/K, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
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Structure-function analysis of the HrpB2-HrcU interaction in the Xanthomonas citri type III secretion system. PLoS One 2011; 6:e17614. [PMID: 21408079 PMCID: PMC3052322 DOI: 10.1371/journal.pone.0017614] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 02/01/2011] [Indexed: 12/02/2022] Open
Abstract
Bacterial type III secretion systems deliver protein virulence factors to host cells. Here we characterize the interaction between HrpB2, a small protein secreted by the Xanthomonas citri subsp. citri type III secretion system, and the cytosolic domain of the inner membrane protein HrcU, a paralog of the flagellar protein FlhB. We show that a recombinant fragment corresponding to the C-terminal cytosolic domain of HrcU produced in E. coli suffers cleavage within a conserved Asn264-Pro265-Thr266-His267 (NPTH) sequence. A recombinant HrcU cytosolic domain with N264A, P265A, T266A mutations at the cleavage site (HrcUAAAH) was not cleaved and interacted with HrpB2. Furthermore, a polypeptide corresponding to the sequence following the NPTH cleavage site also interacted with HrpB2 indicating that the site for interaction is located after the NPTH site. Non-polar deletion mutants of the hrcU and hrpB2 genes resulted in a total loss of pathogenicity in susceptible citrus plants and disease symptoms could be recovered by expression of HrpB2 and HrcU from extrachromossomal plasmids. Complementation of the ΔhrcU mutant with HrcUAAAH produced canker lesions similar to those observed when complemented with wild-type HrcU. HrpB2 secretion however, was significantly reduced in the ΔhrcU mutant complemented with HrcUAAAH, suggesting that an intact and cleavable NPTH site in HrcU is necessary for total functionally of T3SS in X. citri subsp. citri. Complementation of the ΔhrpB2 X. citri subsp. citri strain with a series of hrpB2 gene mutants revealed that the highly conserved HrpB2 C-terminus is essential for T3SS-dependent development of citrus canker symptoms in planta.
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