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Lonjon F, Lai Y, Askari N, Aiyar N, Bundalovic-Torma C, Laflamme B, Wang PW, Desveaux D, Guttman DS. The effector-triggered immunity landscape of tomato against Pseudomonas syringae. Nat Commun 2024; 15:5102. [PMID: 38877009 PMCID: PMC11178782 DOI: 10.1038/s41467-024-49425-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 05/31/2024] [Indexed: 06/16/2024] Open
Abstract
Tomato (Solanum lycopersicum) is one of the world's most important food crops, and as such, its production needs to be protected from infectious diseases that can significantly reduce yield and quality. Here, we survey the effector-triggered immunity (ETI) landscape of tomato against the bacterial pathogen Pseudomonas syringae. We perform comprehensive ETI screens in five cultivated tomato varieties and two wild relatives, as well as an immunodiversity screen on a collection of 149 tomato varieties that includes both wild and cultivated varieties. The screens reveal a tomato ETI landscape that is more limited than what was previously found in the model plant Arabidopsis thaliana. We also demonstrate that ETI eliciting effectors can protect tomato against P. syringae infection when the effector is delivered by a non-virulent strain either prior to or simultaneously with a virulent strain. Overall, our findings provide a snapshot of the ETI landscape of tomatoes and demonstrate that ETI can be used as a biocontrol treatment to protect crop plants.
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Affiliation(s)
- Fabien Lonjon
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Yan Lai
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Nasrin Askari
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Niharikaa Aiyar
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | | | - Bradley Laflamme
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Pauline W Wang
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON, Canada.
| | - David S Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON, Canada.
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2
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Feltin C, Garneau JR, Morris CE, Bérard A, Torres-Barceló C. Novel phages of Pseudomonas syringae unveil numerous potential auxiliary metabolic genes. J Gen Virol 2024; 105. [PMID: 38833289 DOI: 10.1099/jgv.0.001990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024] Open
Abstract
Relatively few phages that infect plant pathogens have been isolated and investigated. The Pseudomonas syringae species complex is present in various environments, including plants. It can cause major crop diseases, such as bacterial canker on apricot trees. This study presents a collection of 25 unique phage genomes that infect P. syringae. These phages were isolated from apricot orchards with bacterial canker symptoms after enrichment with 21 strains of P. syringae. This collection comprises mostly virulent phages, with only three being temperate. They belong to 14 genera, 11 of which are newly discovered, and 18 new species, revealing great genetic diversity within this collection. Novel DNA packaging systems have been identified bioinformatically in one of the new phage species, but experimental confirmation is required to define the precise mechanism. Additionally, many phage genomes contain numerous potential auxiliary metabolic genes with diversified putative functions. At least three phages encode genes involved in bacterial tellurite resistance, a toxic metalloid. This suggests that viruses could play a role in bacterial stress tolerance. This research emphasizes the significance of continuing the search for new phages in the agricultural ecosystem to unravel novel ecological diversity and new gene functions. This work contributes to the foundation for future fundamental and applied research on phages infecting phytopathogenic bacteria.
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Affiliation(s)
- Chloé Feltin
- INRAE, Pathologie Végétale, F-84140, Montfavet, France
| | - Julian R Garneau
- Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland
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3
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Maguvu TE, Frias RJ, Hernandez-Rosas AI, Holtz BA, Niederholzer FJA, Duncan RA, Yaghmour MA, Culumber CM, Gordon PE, Vieira FCF, Rolshausen PE, Adaskaveg JE, Burbank LP, Lindow SE, Trouillas FP. Phylogenomic analyses and comparative genomics of Pseudomonas syringae associated with almond (Prunus dulcis) in California. PLoS One 2024; 19:e0297867. [PMID: 38603730 PMCID: PMC11008872 DOI: 10.1371/journal.pone.0297867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/10/2024] [Indexed: 04/13/2024] Open
Abstract
We sequenced and comprehensively analysed the genomic architecture of 98 fluorescent pseudomonads isolated from different symptomatic and asymptomatic tissues of almond and a few other Prunus spp. Phylogenomic analyses, genome mining, field pathogenicity tests, and in vitro ice nucleation and antibiotic sensitivity tests were integrated to improve knowledge of the biology and management of bacterial blast and bacterial canker of almond. We identified Pseudomonas syringae pv. syringae, P. cerasi, and P. viridiflava as almond canker pathogens. P. syringae pv. syringae caused both canker and foliar (blast) symptoms. In contrast, P. cerasi and P. viridiflava only caused cankers, and P. viridiflava appeared to be a weak pathogen of almond. Isolates belonging to P. syringae pv. syringae were the most frequently isolated among the pathogenic species/pathovars, composing 75% of all pathogenic isolates. P. cerasi and P. viridiflava isolates composed 8.3 and 16.7% of the pathogenic isolates, respectively. Laboratory leaf infiltration bioassays produced results distinct from experiments in the field with both P. cerasi and P. syringae pv. syringae, causing significant necrosis and browning of detached leaves, whereas P. viridiflava conferred moderate effects. Genome mining revealed the absence of key epiphytic fitness-related genes in P. cerasi and P. viridiflava genomic sequences, which could explain the contrasting field and laboratory bioassay results. P. syringae pv. syringae and P. cerasi isolates harboured the ice nucleation protein, which correlated with the ice nucleation phenotype. Results of sensitivity tests to copper and kasugamycin showed a strong linkage to putative resistance genes. Isolates harbouring the ctpV gene showed resistance to copper up to 600 μg/ml. In contrast, isolates without the ctpV gene could not grow on nutrient agar amended with 200 μg/ml copper, suggesting ctpV can be used to phenotype copper resistance. All isolates were sensitive to kasugamycin at the label-recommended rate of 100μg/ml.
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Affiliation(s)
- Tawanda E. Maguvu
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States of America
- Kearney Agricultural Research and Extension Center, Parlier, CA, United States of America
| | - Rosa J. Frias
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States of America
| | | | - Brent A. Holtz
- University of California Cooperative Extension, CA, United States of America
| | | | - Roger A. Duncan
- University of California Cooperative Extension, CA, United States of America
| | | | | | - Phoebe E. Gordon
- University of California Cooperative Extension, CA, United States of America
| | - Flavia C. F. Vieira
- Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA, United States of America
| | - Philippe E. Rolshausen
- Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA, United States of America
| | - James E. Adaskaveg
- Department of Plant Pathology and Microbiology, University of California, Riverside, Riverside, CA, United States of America
| | - Lindsey P. Burbank
- U.S. Department of Agriculture, Agricultural Research Service, Parlier, CA, United States of America
| | - Steven E. Lindow
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States of America
| | - Florent P. Trouillas
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States of America
- Kearney Agricultural Research and Extension Center, Parlier, CA, United States of America
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4
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Lipps SM, Castell-Miller C, Morris CE, Ishii S, Samac DA. Diversity of Strains in the Pseudomonas syringae Complex Causing Bacterial Stem Blight of Alfalfa ( Medicago sativa) in the United States. PHYTOPATHOLOGY 2024; 114:802-812. [PMID: 37913751 DOI: 10.1094/phyto-02-23-0059-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Alfalfa growers in the Intermountain West of the United States have recently seen an increased incidence in bacterial stem blight (BSB), which can result in significant herbage yield losses from the first harvest. BSB has been attributed to Pseudomonas syringae pv. syringae and P. viridiflava; however, little is known about the genetic diversity and pathogenicity of these bacteria or their interaction with alfalfa plants. Here, we present a comprehensive phylogenetic and phenotypic analysis of P. syringae and P. viridiflava strains causing BSB on alfalfa. A multilocus sequence analysis found that they grouped exclusively with P. syringae PG2b and P. viridiflava PG7a. Alfalfa symptoms caused by both bacterial groups were indistinguishable, although there was a large range in mean disease scores for individual strains. Overall, PG2b strains incited significantly greater disease scores than those caused by PG7a strains. Inoculated plants showed browning in the xylem and collapse of epidermal and pith parenchyma cells. Inoculation with a mixture of PG2b and PG7a strains did not result in synergistic activity. The populations of PG2b and PG7a strains were genetically diverse within their clades and did not group by location or haplotype. The PG2b strains had genes for production of the phytotoxin coronatine, which is unusual in PG2b strains. The results indicate that both pathogens are well established on alfalfa across a wide geographic range and that a recent introduction or evolution of more aggressive strains as the basis for emergence of the disease is unlikely.
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Affiliation(s)
- Savana M Lipps
- Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, U.S.A
| | | | | | - Satoshi Ishii
- Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, U.S.A
- BioTechnology Institute, University of Minnesota, St. Paul, MN 55108, U.S.A
| | - Deborah A Samac
- Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, U.S.A
- U.S. Department of Agriculture-Agricultural Research Service-Plant Science Research Unit, St. Paul, MN 55108, U.S.A
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5
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Fautt C, Couradeau E, Hockett KL. Naïve Bayes Classifiers and accompanying dataset for Pseudomonas syringae isolate characterization. Sci Data 2024; 11:178. [PMID: 38326362 PMCID: PMC10850129 DOI: 10.1038/s41597-024-03003-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 01/26/2024] [Indexed: 02/09/2024] Open
Abstract
The Pseudomonas syringae species complex (PSSC) is a diverse group of plant pathogens with a collective host range encompassing almost every food crop grown today. As a threat to global food security, rapid detection and characterization of epidemic and emerging pathogenic lineages is essential. However, phylogenetic identification is often complicated by an unclarified and ever-changing taxonomy, making practical use of available databases and the proper training of classifiers difficult. As such, while amplicon sequencing is a common method for routine identification of PSSC isolates, there is no efficient method for accurate classification based on this data. Here we present a suite of five Naïve bayes classifiers for PCR primer sets widely used for PSSC identification, trained on in-silico amplicon data from 2,161 published PSSC genomes using the life identification number (LIN) hierarchical clustering algorithm in place of traditional Linnaean taxonomy. Additionally, we include a dataset for translating classification results back into traditional taxonomic nomenclature (i.e. species, phylogroup, pathovar), and for predicting virulence factor repertoires.
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Affiliation(s)
- Chad Fautt
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, Pennsylvania, USA.
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania, USA.
- Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, Pennsylvania, USA.
| | - Estelle Couradeau
- Department of Ecosystem Science and Management, Pennsylvania State University, University Park, Pennsylvania, USA.
- Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, Pennsylvania, USA.
| | - Kevin L Hockett
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, Pennsylvania, USA.
- Intercollege Graduate Degree Program in Ecology, Pennsylvania State University, University Park, Pennsylvania, USA.
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6
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Ramírez N, Sigurbjörnsdóttir MA, Monteil C, Berge O, Heiðmarsson S, Jackson RW, Morris C, Vilhelmsson O. Pseudomonas syringae isolated in lichens for the first time: Unveiling Peltigera genus as the exclusive host. Environ Microbiol 2023; 25:3502-3511. [PMID: 37658725 DOI: 10.1111/1462-2920.16490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 08/01/2023] [Indexed: 09/03/2023]
Abstract
Pseudomonas syringae is a bacterial complex that is widespread through a range of environments, typically associated with plants where it can be pathogenic, but also found in non-plant environments such as clouds, precipitation, and surface waters. Understanding its distribution within the environment, and the habitats it occupies, is important for examining its evolution and understanding behaviours. After a recent study found P. syringae living among a range of vascular plant species in Iceland, we questioned whether lichens could harbour P. syringae. Sixteen different species of lichens were sampled all over Iceland, but only one lichen genus, Peltigera, was found to consistently harbour P. syringae. Phylogenetic analyses of P. syringae from 10 sampling points where lichen, tracheophyte, and/or moss were simultaneously collected showed significant differences between sampling points, but not between different plants and lichens from the same point. Furthermore, while there were similarities in the P. syringae population in tracheophytes and Peltigera, the densities in Peltigera thalli were lower than in moss and tracheophyte samples. This discovery suggests P. syringae strains can localize and survive in organisms beyond higher plants, and thus reveals opportunities for studying their influence on P. syringae evolution.
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Affiliation(s)
- Natalia Ramírez
- Department of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
| | | | - Cecile Monteil
- INRA, UR0407 Pathologie Vegétale, Montfavet Cedex, France
| | - Odile Berge
- INRA, UR0407 Pathologie Vegétale, Montfavet Cedex, France
| | | | - Robert W Jackson
- School of Biosciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham, UK
| | - Cindy Morris
- INRA, UR0407 Pathologie Vegétale, Montfavet Cedex, France
| | - Oddur Vilhelmsson
- Department of Natural Resource Sciences, University of Akureyri, Akureyri, Iceland
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7
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Lindow S. History of Discovery and Environmental Role of Ice Nucleating Bacteria. PHYTOPATHOLOGY 2023; 113:605-615. [PMID: 36122194 DOI: 10.1094/phyto-07-22-0256-ia] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The phenomenon of biological ice nucleation that is exhibited by a variety of bacteria is a fascinating phenotype, which has been shown to incite frost damage to frost-sensitive plants and has been proposed to contribute to atmospheric processes that affect the water cycle and earth's radiation balance. This review explores the several possible drivers for the evolutionary origin of the ice nucleation phenotype. These bacteria and the gene required for this phenotype have also been exploited in processes as diverse as reporter gene assays to assess environmentally responsive gene expression in various plant pathogenic and environmental bacteria and in the detection of foodborne human pathogens when coupled with host-specific bacteriophage, whereas ice nucleating bacteria themselves have been exploited in the production of artificial snow for recreation and oil exploration and in the process of freezing of various food products. This review also examines the historical development of our understanding of ice nucleating bacteria, details of the genetic determinants of ice nucleation, and features of the aggregates of membrane-bound ice nucleation protein necessary for catalyzing ice. Lastly, this review also explores the role of these bacteria in limiting the supercooling ability of plants and the strategies and limitations of avoiding plant frost damage by managing these bacterial populations by bactericides, antagonistic bacteria, or cultural control strategies.
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Affiliation(s)
- Steven Lindow
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
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8
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Ranković T, Nikolić I, Berić T, Popović T, Lozo J, Medić O, Stanković S. Genome Analysis of Two Pseudomonas syringae pv. aptata Strains with Different Virulence Capacity Isolated from Sugar Beet: Features of Successful Pathogenicity in the Phyllosphere Microbiome. Microbiol Spectr 2023; 11:e0359822. [PMID: 36912660 PMCID: PMC10100878 DOI: 10.1128/spectrum.03598-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 02/07/2023] [Indexed: 03/14/2023] Open
Abstract
Members of the Pseudomonas syringae species complex are heterogeneous bacteria that are the most abundant bacterial plant pathogens in the plant phyllosphere, with strong abilities to exist on and infect different plant hosts and survive in/outside agroecosystems. In this study, the draft genome sequences of two pathogenic P. syringae pv. aptata strains with different in planta virulence capacities isolated from the phyllosphere of infected sugar beet were analyzed to evaluate putative features of survival strategies and to determine the pathogenic potential of the strains. The draft genomes of P. syringae pv. aptata strains P16 and P21 are 5,974,057 bp and 6,353,752 bp in size, have GC contents of 59.03% and 58.77%, respectively, and contain 3,439 and 3,536 protein-coding sequences, respectively. For both average nucleotide identity and pangenome analysis, P16 and P21 largely clustered with other pv. aptata strains from the same isolation source. We found differences in the repertoire of effectors of the type III secretion system among all 102 selected strains, suggesting that the type III secretion system is a critical factor in the different virulent phenotypes of P. syringae pv. aptata. During genome analysis of the highly virulent strain P21, we discovered genes for T3SS effectors (AvrRpm1, HopAW1, and HopAU1) that were not previously found in genomes of P. syringae pv. aptata. We also identified coding sequences for pantothenate kinase, VapC endonuclease, phospholipase, and pectate lyase in both genomes, which may represent novel effectors of the type III secretion system. IMPORTANCE Genome analysis has an enormous effect on understanding the life strategies of plant pathogens. Comparing similarities with pathogens involved in other epidemics could elucidate the pathogen life cycle when a new outbreak happens. This study represents the first in-depth genome analysis of Pseudomonas syringae pv. aptata, the causative agent of leaf spot disease of sugar beet. Despite the increasing number of disease reports in recent years worldwide, there is still a lack of information about the genomic features, epidemiology, and pathogenic life strategies of this particular pathogen. Our findings provide advances in disease etiology (especially T3SS effector repertoire) and elucidate the role of environmental adaptations required for prevalence in the pathobiome of the sugar beet. From the perspective of the very heterogeneous P. syringae species complex, this type of analysis has specific importance in reporting the characteristics of individual strains.
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Affiliation(s)
- Tamara Ranković
- University of Belgrade, Faculty of Biology, Center for Biological Control and Plant Growth Promotion, Belgrade, Serbia
| | - Ivan Nikolić
- University of Belgrade, Faculty of Biology, Center for Biological Control and Plant Growth Promotion, Belgrade, Serbia
| | - Tanja Berić
- University of Belgrade, Faculty of Biology, Center for Biological Control and Plant Growth Promotion, Belgrade, Serbia
| | - Tatjana Popović
- Institute for Plant Protection and Environment, Belgrade, Serbia
| | - Jelena Lozo
- University of Belgrade, Faculty of Biology, Center for Biological Control and Plant Growth Promotion, Belgrade, Serbia
| | - Olja Medić
- University of Belgrade, Faculty of Biology, Center for Biological Control and Plant Growth Promotion, Belgrade, Serbia
| | - Slaviša Stanković
- University of Belgrade, Faculty of Biology, Center for Biological Control and Plant Growth Promotion, Belgrade, Serbia
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9
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Cooperative virulence via the collective action of secreted pathogen effectors. Nat Microbiol 2023; 8:640-650. [PMID: 36782026 DOI: 10.1038/s41564-023-01328-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 01/13/2023] [Indexed: 02/15/2023]
Abstract
Although virulence is typically attributed to single pathogenic strains, here we investigated whether effectors secreted by a population of non-virulent strains could function as public goods to enable the emergence of collective virulence. We disaggregated the 36 type III effectors of the phytopathogenic bacterium Pseudomonas syringae strain PtoDC3000 into a 'metaclone' of 36 coisogenic strains, each carrying a single effector in an effectorless background. Each coisogenic strain was individually unfit, but the metaclone was collectively as virulent as the wild-type strain on Arabidopsis thaliana, suggesting that effectors can drive the emergence of cooperation-based virulence through their public action. We show that independently evolved effector suits can equally drive this cooperative behaviour by transferring the effector alleles native to the strain PmaES4326 into the conspecific but divergent strain PtoDC3000. Finally, we transferred the disaggregated PtoDC3000 effector arsenal into Pseudomonas fluorescens and show that their cooperative action was sufficient to convert this rhizosphere-inhabiting beneficial bacterium into a phyllosphere pathogen. These results emphasize the importance of microbial community interactions and expand the ecological scale at which disease may be attributed.
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10
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Hulin MT, Rabiey M, Zeng Z, Vadillo Dieguez A, Bellamy S, Swift P, Mansfield JW, Jackson RW, Harrison RJ. Genomic and functional analysis of phage-mediated horizontal gene transfer in Pseudomonas syringae on the plant surface. THE NEW PHYTOLOGIST 2023; 237:959-973. [PMID: 36285389 PMCID: PMC10107160 DOI: 10.1111/nph.18573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
Many strains of Pseudomonas colonise plant surfaces, including the cherry canker pathogens, Pseudomonas syringae pathovars syringae and morsprunorum. We have examined the genomic diversity of P. syringae in the cherry phyllosphere and focused on the role of prophages in transfer of genes encoding Type 3 secreted effector (T3SE) proteins contributing to the evolution of virulence. Phylogenomic analysis was carried out on epiphytic pseudomonads in the UK orchards. Significant differences in epiphytic populations occurred between regions. Nonpathogenic strains were found to contain reservoirs of T3SE genes. Members of P. syringae phylogroups 4 and 10 were identified for the first time from Prunus. Using bioinformatics, we explored the presence of the gene encoding T3SE HopAR1 within related prophage sequences in diverse P. syringae strains including cherry epiphytes and pathogens. Results indicated that horizontal gene transfer (HGT) of this effector between phylogroups may have involved phage. Prophages containing hopAR1 were demonstrated to excise, circularise and transfer the gene on the leaf surface. The phyllosphere provides a dynamic environment for prophage-mediated gene exchange and the potential for the emergence of new more virulent pathotypes. Our results suggest that genome-based epidemiological surveillance of environmental populations will allow the timely application of control measures to prevent damaging diseases.
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Affiliation(s)
- Michelle T. Hulin
- NIABLawrence Weaver RoadCambridgeCB3 0LEUK
- The Sainsbury LaboratoryNorwichNR4 7UHUK
| | - Mojgan Rabiey
- School of Biosciences and the Birmingham Institute of Forest ResearchUniversity of BirminghamBirminghamB15 2TTUK
| | - Ziyue Zeng
- NIABLawrence Weaver RoadCambridgeCB3 0LEUK
| | | | | | - Phoebe Swift
- School of Biosciences and the Birmingham Institute of Forest ResearchUniversity of BirminghamBirminghamB15 2TTUK
| | | | - Robert W. Jackson
- School of Biosciences and the Birmingham Institute of Forest ResearchUniversity of BirminghamBirminghamB15 2TTUK
| | - Richard J. Harrison
- NIABLawrence Weaver RoadCambridgeCB3 0LEUK
- Present address:
Plant Science GroupWageningen University and ResearchWageningen6708WBthe Netherlands
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11
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Type III Secretion System Repressor RhpR Induces GrlP, a Glycine-Rich Outer Membrane Lipoprotein with Functions in Regulating the Periplasmic Space and Pleiotropic Responses. Appl Environ Microbiol 2023; 89:e0158722. [PMID: 36602318 PMCID: PMC9888284 DOI: 10.1128/aem.01587-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The two-component system RhpRS was initially identified as a regulator of genes encoding the type III secretion system (T3SS) in Pseudomonas syringae. Phosphorylated RhpR (P-RhpR) negatively regulates the T3SS genes by repressing the hrpR promoter, but directly activates the expression of a small gene named here as grlp. Here, we show that grlp is expressed higher in rich medium than in minimal medium in P. s. pv. tomato DC3000 and encodes a glycine rich lipoprotein (GrlP) located in the outer membrane (OM). The grlp gene has a pleiotropic effect on bacterial behaviors such as reductions in pathogenicity, swimming motility, biofilm formation, tolerance to various stresses and antibiotics, and long-term survival when overexpressed, but induces these responses when it is deleted in P. s. pv. tomato DC3000. Overexpression of grlp increases the size of periplasm while deletion of grlp decreases the periplasmic space. Further, GrlP interacts with OprI, the ortholog of E. coli OM lipoprotein Lpp, a key player in determining the size of periplasm and mechanic stiffness of the OM by tethering the OM to peptidoglycan (PG) in periplasm. As periplasmic space and OM mechanics play central roles in regulating bacterial physiology, we speculate that GrlP probably imposes its functions on bacterial physiology by regulating the periplasmic space and OM mechanics. These findings suggest that the T3SS gene regulation is closely coordinated with bacterial cell envelope properties by RhpRS in P. syringe. IMPORTANCE The OM of Gram-negative bacteria is the most front line in contact with extracellular milieu. OM is not only a protective layer, but also a structure that determines the envelope stiffness. Recent evidence indicated that components determining the periplasmic space and cross-links of lipopolysaccharide on the OM play key roles in regulating the mechanical properties of the OM. However, whether the OM composition and mechanical properties are coordinated with the expression of the T3SS genes is unknown. Here, we found that the two-component system (TCS) regulator P-RhpR, a direct repressor of the T3SS regulator hrpRS operon, directly activates the expression of the OM lipoprotein gene grlp bearing a function in regulating the periplasmic space. This finding suggests a coordination between the OM properties and the T3SS gene regulation and reveals a new target for control of the T3SS gene expression and bacterial pathogenicity.
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12
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Bricout A, Morris CE, Chandeysson C, Duban M, Boistel C, Chataigné G, Lecouturier D, Jacques P, Leclère V, Rochex A. The Diversity of Lipopeptides in the Pseudomonas syringae Complex Parallels Phylogeny and Sheds Light on Structural Diversification during Evolutionary History. Microbiol Spectr 2022; 10:e0145622. [PMID: 36287007 PMCID: PMC9769872 DOI: 10.1128/spectrum.01456-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 08/12/2022] [Indexed: 01/05/2023] Open
Abstract
Pseudomonas spp. colonize diverse aquatic and terrestrial habitats and produce a wide variety of secondary metabolites, including lipopeptides. However, previous studies have often examined a limited number of lipopeptide-producing strains. In this study, we performed a systematic analysis of lipopeptide production across a wide data set of strains of the Pseudomonas syringae complex (724) by using a combined bioinformatics, mass spectrometry, and phylogenetics approach. The large P. syringae complex, which is composed of 13 phylogroups, is known to produce factins (including syringafactin-like lipopeptides), mycins (including syringomycin-like lipopeptides), and peptins (such as syringopeptins). We found that 80.8% of P. syringae strains produced lipopeptides and that factins were the most frequently produced (by 96% of the producing strains). P. syringae strains were either factin monoproducers or factin, mycin, and peptin coproducers or lipopeptide nonproducers in relation to their phylogenetic group. Our analyses led to the discovery of 42 new lipopeptides, bringing the number of lipopeptides identified in the P. syringae complex to 75. We also highlighted that factins have high structural resemblance and are widely distributed among the P. syringae complex, while mycins and peptins are highly structurally diverse and patchily distributed. IMPORTANCE This study provides an insight into the P. syringae metabolome that emphasizes the high diversity of lipopeptides produced within the P. syringae complex. The production profiles of strains are closely related to their phylogenetic classification, indicating that structural diversification of lipopeptides parallels the phylogeny of this bacterial complex, thereby further illustrating the inherent importance of lipopeptides in the ecology of this group of bacteria throughout its evolutionary history. Furthermore, this overview of P. syringae lipopeptides led us to propose a refined classification that could be extended to the lipopeptides produced by other bacterial groups.
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Affiliation(s)
- Alexandre Bricout
- Université de Lille, Université de Liège, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, Charles Viollette Institute, Lille, France
- Agence de la transition écologique (ADEME), Angers, France
| | | | | | - Matthieu Duban
- Université de Lille, Université de Liège, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, Charles Viollette Institute, Lille, France
| | - Corinne Boistel
- Université de Lille, Université de Liège, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, Charles Viollette Institute, Lille, France
| | - Gabrielle Chataigné
- Université de Lille, Université de Liège, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, Charles Viollette Institute, Lille, France
| | - Didier Lecouturier
- Université de Lille, Université de Liège, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, Charles Viollette Institute, Lille, France
| | - Philippe Jacques
- Université de Liège, Université de Lille, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, Gembloux, Belgium
| | - Valérie Leclère
- Université de Lille, Université de Liège, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, Charles Viollette Institute, Lille, France
| | - Alice Rochex
- Université de Lille, Université de Liège, UMRt BioEcoAgro 1158-INRAE, Métabolites Secondaires d’Origine Microbienne, Charles Viollette Institute, Lille, France
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13
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Identification of Candidate Ice Nucleation Activity (INA) Genes in Fusarium avenaceum by Combining Phenotypic Characterization with Comparative Genomics and Transcriptomics. J Fungi (Basel) 2022; 8:jof8090958. [PMID: 36135683 PMCID: PMC9501429 DOI: 10.3390/jof8090958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 11/19/2022] Open
Abstract
Ice nucleation activity (INA) is the capacity of certain particles to catalyze ice formation at temperatures higher than the temperature at which pure water freezes. INA impacts the ratio of liquid to frozen cloud droplets and, therefore, the formation of precipitation and Earth’s radiative balance. Some Fusarium strains secrete ice-nucleating particles (INPs); they travel through the atmosphere and may thus contribute to these atmospheric processes. Fusarium INPs were previously found to consist of proteinaceous aggregates. Here, we determined that in F. avenaceum, the proteins forming these aggregates are smaller than 5 nm and INA is higher after growth at low temperatures and varies among strains. Leveraging these findings, we used comparative genomics and transcriptomics to identify candidate INA genes. Ten candidate INA genes that were predicted to encode secreted proteins were present only in the strains that produced the highest number of INPs. In total, 203 candidate INA genes coding for secreted proteins were induced at low temperatures. Among them, two genes predicted to encode hydrophobins stood out because hydrophobins are small, secreted proteins that form aggregates with amphipathic properties. We discuss the potential of the candidate genes to encode INA proteins and the next steps necessary to identify the molecular basis of INA in F. avenaceum.
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Bundalovic-Torma C, Lonjon F, Desveaux D, Guttman DS. Diversity, Evolution, and Function of Pseudomonas syringae Effectoromes. ANNUAL REVIEW OF PHYTOPATHOLOGY 2022; 60:211-236. [PMID: 35537470 DOI: 10.1146/annurev-phyto-021621-121935] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pseudomonas syringae is an evolutionarily diverse bacterial species complex and a preeminent model for the study of plant-pathogen interactions due in part to its remarkably broad host range. A critical feature of P. syringae virulence is the employment of suites of type III secreted effector (T3SE) proteins, which vary widely in composition and function. These effectors act on a variety of plant intracellular targets to promote pathogenesis but can also be avirulence factors when detected by host immune complexes. In this review, we survey the phylogenetic diversity (PD) of the P. syringae effectorome, comprising 70 distinct T3SE families identified to date, and highlight how avoidance of host immune detection has shaped effectorome diversity through functional redundancy, diversification, and horizontal transfer. We present emerging avenues for research and novel insights that can be gained via future investigations of plant-pathogen interactions through the fusion of large-scale interaction screens and phylogenomic approaches.
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Affiliation(s)
| | - Fabien Lonjon
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada; ,
| | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada; ,
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - David S Guttman
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada; ,
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
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15
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Ben Moussa H, Bertrand C, Rochelle-Newall E, Fiorini S, Pédron J, Barny MA. The Diversity and Abundance of Soft Rot Pectobacteriaceae Along the Durance River Stream in the Southeast of France Revealed by Multiple Seasonal Surveys. PHYTOPATHOLOGY 2022; 112:1676-1685. [PMID: 35224981 DOI: 10.1094/phyto-12-21-0515-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Although irrigation water is frequently assessed for the presence of plant pathogens, large spatial and temporal surveys that provide clues on the diversity and circulation of pathogens are missing. We evaluate the diversity of soft rot Pectobacteriaceae (SRP) of the genera Dickeya and Pectobacterium over 2 years in a temperate, mixed-use watershed. The abundance of isolated strains correlates with the agricultural gradient along the watershed with a positive correlation found with temperature, nitrate, and dissolved organic carbon water concentration. We characterized 582 strains by amplification and sequencing of the gapA gene. Multilocus sequence analysis, performed with three housekeeping genes for 99 strains, and core genome analysis of 38 sequenced strains, confirmed for all the strains but one, the taxonomic assignation obtained with the sole gapA sequence. Pectobacterium spp. (549 isolates) were far more abundant than Dickeya spp. (33 isolates). Dickeya spp. were only observed in the lower part of the river when water temperature was >19°C, and we experimentally confirmed a decreased fitness of several Dickeya spp. at 8°C in river water. D. oryzae dominates the Dickeya spp. and P. versatile and P. aquaticum dominate the Pectobacterium spp., but their repartition along the watershed was different, with P. versatile being the only species regularly recovered all along the watershed. Excepting P. versatile, the Dickeya and Pectobacterium spp. responsible for disease outbreak on crops were less abundant or rarely detected. This work sheds light on the various ecological behaviors of different SRP types in stream water and indicates that SRP occupation is geographically structured.
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Affiliation(s)
- Hajar Ben Moussa
- Sorbonne Université, Institut National de Recherche pour l'Agriculture, l'alimentation et l'Environnement, Institut de Recherche pour le Développement, Centre National de la Recherche Scientifique, Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris, UMR 7618, F-75252 Paris, France
| | - Claire Bertrand
- Sorbonne Université, Institut National de Recherche pour l'Agriculture, l'alimentation et l'Environnement, Institut de Recherche pour le Développement, Centre National de la Recherche Scientifique, Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris, UMR 7618, F-75252 Paris, France
| | - Emma Rochelle-Newall
- Sorbonne Université, Institut National de Recherche pour l'Agriculture, l'alimentation et l'Environnement, Institut de Recherche pour le Développement, Centre National de la Recherche Scientifique, Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris, UMR 7618, F-75252 Paris, France
| | - Sarah Fiorini
- Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Centre de Recherche en Écologie Expérimentale et Prédictive, Paris Sciences & Lettres Research University, UMS 3194, 77140 Saint-Pierre-lès-Nemours, France
| | - Jacques Pédron
- Sorbonne Université, Institut National de Recherche pour l'Agriculture, l'alimentation et l'Environnement, Institut de Recherche pour le Développement, Centre National de la Recherche Scientifique, Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris, UMR 7618, F-75252 Paris, France
| | - Marie-Anne Barny
- Sorbonne Université, Institut National de Recherche pour l'Agriculture, l'alimentation et l'Environnement, Institut de Recherche pour le Développement, Centre National de la Recherche Scientifique, Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris, UMR 7618, F-75252 Paris, France
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16
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Almeida RND, Greenberg M, Bundalovic-Torma C, Martel A, Wang PW, Middleton MA, Chatterton S, Desveaux D, Guttman DS. Predictive modeling of Pseudomonas syringae virulence on bean using gradient boosted decision trees. PLoS Pathog 2022; 18:e1010716. [PMID: 35877772 PMCID: PMC9352200 DOI: 10.1371/journal.ppat.1010716] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 08/04/2022] [Accepted: 06/30/2022] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas syringae is a genetically diverse bacterial species complex responsible for numerous agronomically important crop diseases. Individual P. syringae isolates are assigned pathovar designations based on their host of isolation and the associated disease symptoms, and these pathovar designations are often assumed to reflect host specificity although this assumption has rarely been rigorously tested. Here we developed a rapid seed infection assay to measure the virulence of 121 diverse P. syringae isolates on common bean (Phaseolus vulgaris). This collection includes P. syringae phylogroup 2 (PG2) bean isolates (pathovar syringae) that cause bacterial spot disease and P. syringae phylogroup 3 (PG3) bean isolates (pathovar phaseolicola) that cause the more serious halo blight disease. We found that bean isolates in general were significantly more virulent on bean than non-bean isolates and observed no significant virulence difference between the PG2 and PG3 bean isolates. However, when we compared virulence within PGs we found that PG3 bean isolates were significantly more virulent than PG3 non-bean isolates, while there was no significant difference in virulence between PG2 bean and non-bean isolates. These results indicate that PG3 strains have a higher level of host specificity than PG2 strains. We then used gradient boosting machine learning to predict each strain’s virulence on bean based on whole genome k-mers, type III secreted effector k-mers, and the presence/absence of type III effectors and phytotoxins. Our model performed best using whole genome data and was able to predict virulence with high accuracy (mean absolute error = 0.05). Finally, we functionally validated the model by predicting virulence for 16 strains and found that 15 (94%) had virulence levels within the bounds of estimated predictions. This study strengthens the hypothesis that P. syringae PG2 strains have evolved a different lifestyle than other P. syringae strains as reflected in their lower level of host specificity. It also acts as a proof-of-principle to demonstrate the power of machine learning for predicting host specific adaptation. Pseudomonas syringae is a genetically diverse Gammaproteobacterial species complex responsible for numerous agronomically important crop diseases. Strains in the P. syringae species complex are frequently categorized into pathovars depending on pathogenic characteristics such as host of isolation and disease symptoms. Common bean pathogens from P. syringae are known to cause two major diseases: (1) pathovar phaseolicola strains from phylogroup 3 cause halo blight disease, characterized by large necrotic lesions surrounded by a chlorotic zone or halo of yellow tissue; and (2) pathovar syringae strains from phylogroup 2 causes bacterial spot disease, characterized by brown leaf spots. While halo blight can cause serious crop losses, bacterial spot disease is generally of minor agronomic concern. Recently, statistical genetic and machine learning approaches have been applied to genomic data to identify genes underlying traits of interest or predict the outcome of host-microbe interactions. Here, we apply machine learning to P. syringae genomic data to predict virulence on bean. We first characterized the virulence of P. syringae isolates on common bean using a seed infection assay and then applied machine learning to the genomic data from the same strains to generate a predictive model for virulence on bean. We found that machine learning models built with k-mers from either full genome data or virulence factors could predict bean virulence with high accuracy. We also confirmed prior work showing that phylogroup 3 halo blight pathogens display a stronger degree of phylogenetic clustering and host specificity compared to phylogroup 2 brown spot pathogens. This works serves as a proof-of-principle for the power of machine learning for predicting host specificity and may find utility in agricultural diagnostic microbiology.
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Affiliation(s)
- Renan N. D. Almeida
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
| | - Michael Greenberg
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
| | | | - Alexandre Martel
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
| | - Pauline W. Wang
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Canada
| | - Maggie A. Middleton
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Canada
| | - Syama Chatterton
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Canada
| | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
| | - David S. Guttman
- Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Canada
- * E-mail:
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17
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Metaeffector interactions modulate the type III effector-triggered immunity load of Pseudomonas syringae. PLoS Pathog 2022; 18:e1010541. [PMID: 35576228 PMCID: PMC9135338 DOI: 10.1371/journal.ppat.1010541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 05/26/2022] [Accepted: 04/21/2022] [Indexed: 11/19/2022] Open
Abstract
The bacterial plant pathogen Pseudomonas syringae requires type III secreted effectors (T3SEs) for pathogenesis. However, a major facet of plant immunity entails the recognition of a subset of P. syringae’s T3SEs by intracellular host receptors in a process called Effector-Triggered Immunity (ETI). Prior work has shown that ETI-eliciting T3SEs are pervasive in the P. syringae species complex raising the question of how P. syringae mitigates its ETI load to become a successful pathogen. While pathogens can evade ETI by T3SE mutation, recombination, or loss, there is increasing evidence that effector-effector (a.k.a., metaeffector) interactions can suppress ETI. To study the ETI-suppression potential of P. syringae T3SE repertoires, we compared the ETI-elicitation profiles of two genetically divergent strains: P. syringae pv. tomato DC3000 (PtoDC3000) and P. syringae pv. maculicola ES4326 (PmaES4326), which are both virulent on Arabidopsis thaliana but harbour largely distinct effector repertoires. Of the 529 T3SE alleles screened on A. thaliana Col-0 from the P. syringae T3SE compendium (PsyTEC), 69 alleles from 21 T3SE families elicited ETI in at least one of the two strain backgrounds, while 50 elicited ETI in both backgrounds, resulting in 19 differential ETI responses including two novel ETI-eliciting families: AvrPto1 and HopT1. Although most of these differences were quantitative, three ETI responses were completely absent in one of the pathogenic backgrounds. We performed ETI suppression screens to test if metaeffector interactions contributed to these ETI differences, and found that HopQ1a suppressed AvrPto1m-mediated ETI, while HopG1c and HopF1g suppressed HopT1b-mediated ETI. Overall, these results show that P. syringae strains leverage metaeffector interactions and ETI suppression to overcome the ETI load associated with their native T3SE repertoires.
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18
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Morris CE, Ramirez N, Berge O, Lacroix C, Monteil C, Chandeysson C, Guilbaud C, Blischke A, Sigurbjörnsdóttir MA, Vilhelmsson OÞ. Pseudomonas syringae on Plants in Iceland Has Likely Evolved for Several Million Years Outside the Reach of Processes That Mix This Bacterial Complex across Earth’s Temperate Zones. Pathogens 2022; 11:pathogens11030357. [PMID: 35335680 PMCID: PMC8951587 DOI: 10.3390/pathogens11030357] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/03/2022] [Accepted: 03/08/2022] [Indexed: 12/04/2022] Open
Abstract
Here we report, for the first time, the occurrence of the bacteria from the species complex Pseudomonas syringae in Iceland. We isolated this bacterium from 35 of the 38 samples of angiosperms, moss, ferns and leaf litter collected across the island from five habitat categories (boreal heath, forest, subalpine and glacial scrub, grazed pasture, lava field). The culturable populations of P. syringae on these plants varied in size across 6 orders of magnitude, were as dense as 107 cfu g−1 and were composed of strains in phylogroups 1, 2, 4, 6, 7, 10 and 13. P. syringae densities were significantly greatest on monocots compared to those on dicots and mosses and were about two orders of magnitude greater in grazed pastures compared to all other habitats. The phylogenetic diversity of 609 strains of P. syringae from Iceland was compared to that of 933 reference strains of P. syringae from crops and environmental reservoirs collected from 27 other countries based on a 343 bp sequence of the citrate synthase (cts) housekeeping gene. Whereas there were examples of identical cts sequences across multiple countries and continents among the reference strains indicating mixing among these countries and continents, the Icelandic strains grouped into monophyletic lineages that were unique compared to all of the reference strains. Based on estimates of the time of divergence of the Icelandic genetic lineages of P. syringae, the geological, botanical and land use history of Iceland, and atmospheric circulation patterns, we propose scenarios whereby it would be feasible for P. syringae to have evolved outside the reach of processes that tend to mix this bacterial complex across the planet elsewhere.
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Affiliation(s)
- Cindy E. Morris
- INRAE, Pathologie Végétale, F-84140 Montfavet, France; (O.B.); (C.L.); (C.M.); (C.C.); (C.G.)
- Correspondence:
| | - Natalia Ramirez
- Faculty of Natural Resource Sciences, University of Akureyri, 600 Akureyri, Iceland; (N.R.); (M.A.S.); (O.Þ.V.)
| | - Odile Berge
- INRAE, Pathologie Végétale, F-84140 Montfavet, France; (O.B.); (C.L.); (C.M.); (C.C.); (C.G.)
| | - Christelle Lacroix
- INRAE, Pathologie Végétale, F-84140 Montfavet, France; (O.B.); (C.L.); (C.M.); (C.C.); (C.G.)
| | - Cécile Monteil
- INRAE, Pathologie Végétale, F-84140 Montfavet, France; (O.B.); (C.L.); (C.M.); (C.C.); (C.G.)
| | - Charlotte Chandeysson
- INRAE, Pathologie Végétale, F-84140 Montfavet, France; (O.B.); (C.L.); (C.M.); (C.C.); (C.G.)
| | - Caroline Guilbaud
- INRAE, Pathologie Végétale, F-84140 Montfavet, France; (O.B.); (C.L.); (C.M.); (C.C.); (C.G.)
| | - Anett Blischke
- ÍSOR, Iceland GeoSurvey, Rangárvöllum við Hlíðarfjallsveg, 600 Akureyri, Iceland;
| | | | - Oddur Þ. Vilhelmsson
- Faculty of Natural Resource Sciences, University of Akureyri, 600 Akureyri, Iceland; (N.R.); (M.A.S.); (O.Þ.V.)
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Bundalovic-Torma C, Desveaux D, Guttman DS. RecPD: A Recombination-aware measure of phylogenetic diversity. PLoS Comput Biol 2022; 18:e1009899. [PMID: 35192600 PMCID: PMC8896707 DOI: 10.1371/journal.pcbi.1009899] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/04/2022] [Accepted: 02/07/2022] [Indexed: 12/22/2022] Open
Abstract
A critical step in studying biological features (e.g., genetic variants, gene families, metabolic capabilities, or taxa) is assessing their diversity and distribution among a sample of individuals. Accurate assessments of these patterns are essential for linking features to traits or outcomes of interest and understanding their functional impact. Consequently, it is of crucial importance that the measures employed for quantifying feature diversity can perform robustly under any evolutionary scenario. However, the standard measures used for quantifying and comparing the distribution of features, such as prevalence, phylogenetic diversity, and related approaches, either do not take into consideration evolutionary history, or assume strictly vertical patterns of inheritance. Consequently, these approaches cannot accurately assess diversity for features that have undergone recombination or horizontal transfer. To address this issue, we have devised RecPD, a novel recombination-aware phylogenetic-diversity statistic for measuring the distribution and diversity of features under all evolutionary scenarios. RecPD utilizes ancestral-state reconstruction to map the presence / absence of features onto ancestral nodes in a species tree, and then identifies potential recombination events in the evolutionary history of the feature. We also derive several related measures from RecPD that can be used to assess and quantify evolutionary dynamics and correlation of feature evolutionary histories. We used simulation studies to show that RecPD reliably reconstructs feature evolutionary histories under diverse recombination and loss scenarios. We then applied RecPD in two diverse real-world scenarios including a preliminary study type III effector protein families secreted by the plant pathogenic bacterium Pseudomonas syringae and growth phenotypes of the Pseudomonas genus and demonstrate that prevalence is an inadequate measure that obscures the potential impact of recombination. We believe RecPD will have broad utility for revealing and quantifying complex evolutionary processes for features at any biological level. Phylogenetic diversity is an important concept utilized in evolutionary ecology which has extensive applications in population genetics to help us understand how evolutionary processes have distributed genetic variation among individuals of a species, and how this impacts phenotypic diversification over time. However, existing approaches for studying phylogenetic diversity largely assume that the genetic features follow vertical inheritance, which is frequently violated in the case of microbial genomes due to horizontal transfer. To address this shortcoming, we present RecPD, a recombination-aware phylogenetic diversity measure, which incorporates ancestral state reconstruction to quantify the phylogenetic diversity of genetic features mapped onto a species phylogeny. Through simulation experiments we show that RecPD robustly reconstructs the evolutionary histories of features evolving under various scenarios of recombination and loss. When applied to a real-world example of type III secreted effector protein families from the plant pathogenic bacterium Pseudomonas syringae, RecPD reveals that horizontal transfer has played an important role in shaping the phylogenetic distributions of a substantial proportion of families across the P. syringae species complex. Furthermore, we demonstrate that the traditional measures of feature prevalence are unsuitable as a measure for comparing feature diversity. We also provide a R package implementation of RecPD for public use: https://github.com/cedatorma/recpd.
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Affiliation(s)
| | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - David S. Guttman
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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20
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Baloh P, Hanlon R, Anderson C, Dolan E, Pacholik G, Stinglmayr D, Burkart J, Felgitsch L, Schmale DG, Grothe H. Seasonal ice nucleation activity of water samples from alpine rivers and lakes in Obergurgl, Austria. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 800:149442. [PMID: 34426361 DOI: 10.1016/j.scitotenv.2021.149442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 06/29/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Abstract
Heterogeneous ice nucleation plays an important role in many environmental processes such as ice cloud formation, freezing of water bodies or biological freeze protection in the cryosphere. New information is needed about the seasonal availability, nature, and activity of ice nucleating particles (INPs) in alpine environments. These INPs trigger the phase transition from liquid water to solid ice at elevated subzero temperatures. We collected water samples from a series of alpine rivers and lakes (two valleys and their rivers, an artificial pond, and a natural lake system) in Obergurgl, Austria in June 2016, July 2016, November 2016, and May 2017. Each alpine river and lake was sampled multiple times across different seasons, depending on site access during different times of the year. Water samples were filtered through a 0.22 μm membrane filter to separate microbial INPs from the water, and both fractions were analyzed for ice nucleation activity (INA) by an emulsion freezing method. Microorganisms were cultured from the filters, and the cultures then analyzed for INA. Portions of the filtered samples were concentrated by lyophilization to observe potential enhancement of INA. Two sediment samples were taken as reference points for inorganic INPs. Sub-micron INPs were observed in all of the alpine water sources studied, and a seasonal shift to a higher fraction of microbial ice nucleators cultured on selective media was observed during the winter collections. Particles larger than 0.22 μm showed INA, and microbes were cultured from this fraction. Results from 60 samples gave evidence of a seasonal change in INA, presence of submicrometer INPs, and show the abundance of culturable microorganisms, with late spring and early summer showing the most active biological INPs. With additional future research on this topic ski resorts could make use of such knowledge of geographical and seasonal trends of microbial INPs in freshwater habitats in order to improve the production of artificial snow.
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Affiliation(s)
- Philipp Baloh
- Institute of Materials Chemistry, TU Wien, Vienna, Austria
| | - Regina Hanlon
- School of Plant and Environmental Sciences, Blacksburg, VA, USA
| | | | - Eoin Dolan
- Institute of Materials Chemistry, TU Wien, Vienna, Austria
| | | | | | - Julia Burkart
- Institute of Materials Chemistry, TU Wien, Vienna, Austria; Faculty of Physics, University of Vienna, Vienna, Austria
| | | | - David G Schmale
- School of Plant and Environmental Sciences, Blacksburg, VA, USA
| | - Hinrich Grothe
- Institute of Materials Chemistry, TU Wien, Vienna, Austria.
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21
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Double agent indole-3-acetic acid (IAA): Mechanistic analysis of indole-3-acetaldehyde dehydrogenase AldA that synthesizes IAA, an auxin that aids bacterial virulence. Biosci Rep 2021; 41:229488. [PMID: 34369556 PMCID: PMC8385190 DOI: 10.1042/bsr20210598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/10/2021] [Accepted: 07/30/2021] [Indexed: 11/17/2022] Open
Abstract
The large diversity of organisms inhabiting various environmental niches on our planet are engaged in a lively exchange of biomolecules, including nutrients, hormones, and vitamins. In a quest to survive, organisms that we define as pathogens employ innovative methods to extract valuable resources from their host leading to an infection. One such instance is where plant-associated bacterial pathogens synthesize and deploy hormones or their molecular mimics to manipulate the physiology of the host plant. This commentary describes one such specific example—the mechanism of the enzyme AldA, an aldehyde dehydrogenase (ALDH) from the bacterial plant pathogen Pseudomonas syringae which produces the plant auxin hormone indole-3-acetic acid (IAA) by oxidizing the substrate indole-3-acetaldehyde (IAAld) using the cofactor nicotinamide adenine dinucleotide (NAD+) (Bioscience Reports (2020) 40(12), https://doi.org/10.1042/BSR20202959). Using mutagenesis, enzyme kinetics, and structural analysis, Zhang et al. established that the progress of the reaction hinges on the formation of two distinct conformations of NAD(H) during the reaction course. Additionally, a key mutation in the AldA active site ‘aromatic box’ changes the enzyme’s preference for an aromatic substrate to an aliphatic one. Our commentary concludes that such molecular level investigations help to establish the nature of the dynamics of NAD(H) in ALDH-catalyzed reactions, and further show that the key active site residues control substrate specificity. We also contemplate that insights from the present study can be used to engineer novel ALDH enzymes for environmental, health, and industrial applications.
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22
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Martel A, Ruiz-Bedoya T, Breit-McNally C, Laflamme B, Desveaux D, Guttman DS. The ETS-ETI cycle: evolutionary processes and metapopulation dynamics driving the diversification of pathogen effectors and host immune factors. CURRENT OPINION IN PLANT BIOLOGY 2021; 62:102011. [PMID: 33677388 DOI: 10.1016/j.pbi.2021.102011] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/21/2021] [Accepted: 01/24/2021] [Indexed: 05/13/2023]
Abstract
The natural diversity of pathogen effectors and host immune components represents a snapshot of the underlying evolutionary processes driving the host-pathogen arms race. In plants, this arms race is manifested by an ongoing cycle of disease and resistance driven by pathogenic effectors that promote disease (effector-triggered susceptibility; ETS) and plant resistance proteins that recognize effector activity to trigger immunity (effector-triggered immunity; ETI). Here we discuss how this ongoing ETS-ETI cycle has shaped the natural diversity of both plant resistance proteins and pathogen effectors. We focus on the evolutionary forces that drive the diversification of the molecules that determine the outcome of plant-pathogen interactions and introduce the concept of metapopulation dynamics (i.e., the introduction of genetic variation from conspecific organisms in different populations) as an alternative mechanism that can introduce and maintain diversity in both host and pathogen populations.
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Affiliation(s)
- Alexandre Martel
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M6S2Y1, Canada
| | - Tatiana Ruiz-Bedoya
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M6S2Y1, Canada
| | - Clare Breit-McNally
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M6S2Y1, Canada
| | - Bradley Laflamme
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M6S2Y1, Canada
| | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M6S2Y1, Canada; Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario M6S2Y1, Canada.
| | - David S Guttman
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario M6S2Y1, Canada; Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario M6S2Y1, Canada.
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23
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Dillon MM, Ruiz-Bedoya T, Bundalovic-Torma C, Guttman KM, Kwak H, Middleton MA, Wang PW, Horuz S, Aysan Y, Guttman DS. Comparative genomic insights into the epidemiology and virulence of plant pathogenic pseudomonads from Turkey. Microb Genom 2021; 7. [PMID: 34227931 PMCID: PMC8477409 DOI: 10.1099/mgen.0.000585] [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] [Indexed: 12/31/2022] Open
Abstract
Pseudomonas is a highly diverse genus that includes species that cause disease in both plants and animals. Recently, pathogenic pseudomonads from the Pseudomonas syringae and Pseudomonas fluorescens species complexes have caused significant outbreaks in several agronomically important crops in Turkey, including tomato, citrus, artichoke and melon. We characterized 169 pathogenic Pseudomonas strains associated with recent outbreaks in Turkey via multilocus sequence analysis and whole-genome sequencing, then used comparative and evolutionary genomics to characterize putative virulence mechanisms. Most of the isolates are closely related to other plant pathogens distributed among the primary phylogroups of P. syringae, although there are significant numbers of P. fluorescens isolates, which is a species better known as a rhizosphere-inhabiting plant-growth promoter. We found that all 39 citrus blast pathogens cluster in P. syringae phylogroup 2, although strains isolated from the same host do not cluster monophyletically, with lemon, mandarin orange and sweet orange isolates all being intermixed throughout the phylogroup. In contrast, 20 tomato pith pathogens are found in two independent lineages: one in the P. syringae secondary phylogroups, and the other from the P. fluorescens species complex. These divergent pith necrosis strains lack characteristic virulence factors like the canonical tripartite type III secretion system, large effector repertoires and the ability to synthesize multiple bacterial phytotoxins, suggesting they have alternative molecular mechanisms to cause disease. These findings highlight the complex nature of host specificity among plant pathogenic pseudomonads.
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Affiliation(s)
- Marcus M Dillon
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.,Present address: Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canada
| | - Tatiana Ruiz-Bedoya
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | | | - Kevin M Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Haejin Kwak
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Maggie A Middleton
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
| | - Pauline W Wang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
| | - Sumer Horuz
- Department of Plant Protection, Erciyes University, Kayseri, Turkey
| | - Yesim Aysan
- Department of Plant Protection, University of Çukurova, Adana, Turkey
| | - David S Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
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24
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Livingston DP, Bertrand A, Wisniewski M, Tisdale R, Tuong T, Gusta LV, Artlip T. Factors contributing to ice nucleation and sequential freezing of leaves in wheat. PLANTA 2021; 253:124. [PMID: 34014374 PMCID: PMC8137482 DOI: 10.1007/s00425-021-03637-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 05/01/2021] [Indexed: 06/03/2023]
Abstract
Anatomical, metabolic and microbial factors were identified that contribute to sequential freezing in wheat leaves and likely contribute to supercooling in the youngest leaves and potentially meristematic regions. Infrared thermography (IR) has been used to observe wheat leaves freezing independently and in an age-related sequence with older leaves freezing first. To determine mechanisms that might explain this sequence of freezing several analytical approaches were used: (1) The size of xylem vessels, in proximity to where freezing initiated, was measured to see if capillary freezing point depression explained sequential freezing. The sequence of freezing in the four youngest leaves was correlated, with the largest vessels freezing first. (2) Carbohydrate and amino acids were analyzed to determine if solute concentrations as well as interactions with membranes explained the freezing sequence. Sucrose was highly correlated to the freezing sequence for all leaves suggesting a prominent role for this sugar as compared to other simple sugars and fructans. Among individual free amino acids proline and serine were correlated to the freezing sequence, with younger leaves having the highest concentrations. (3) Microflora within and on leaf surfaces were determined to measure potential freezing initiation. Levels of bacteria and fungi were correlated to the freezing sequence for all leaves, and species or genera associated with high ice nucleation activity were absent in younger leaves. Moisture content and transcript expression of ice binding proteins were also measured. As expected, our results show that no single mechanism explains the freezing sequence observed via infrared analyses. While these multiple mechanisms are operative at different levels according to the leaf age, they seem to converge when it comes to the protection of vital meristematic tissues. This provides potential phenotypic characters that could be used by breeders to develop more winter-hardy genotypes.
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Affiliation(s)
- D P Livingston
- USDA-ARS and North Carolina State University, Raleigh, NC, 27607, USA.
| | - A Bertrand
- Quebec Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Hochelaga Boulevard, Québec, QC, G1V 2J3, Canada
| | - M Wisniewski
- USDA-ARS, Appalachian Fruit Research Station, Kearneysville, WV, USA
- Virginia Polytechnic Institute, Blacksburg, VA, 24061, USA
| | - R Tisdale
- USDA-ARS and North Carolina State University, Raleigh, NC, 27607, USA
| | - T Tuong
- USDA-ARS and North Carolina State University, Raleigh, NC, 27607, USA
| | - L V Gusta
- Department of Plant Science, Univ Saskatchewan, Saskatoon, Canada
| | - T Artlip
- USDA-ARS, Appalachian Fruit Research Station, Kearneysville, WV, 25430, USA
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25
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Rhoufal F, Guesmi S, Ketatni EM, Jouffret L, Hlil EK, Sergent N, Obbade S, Bentiss F. First divalent copper complex of a terdentate thiosemicarbazido-pyrazoline derived from 2,4-pentanedione bis(thiosemicarbazone): Synthesis, structural characterisation and antimicrobial in vitro activity assessment. Polyhedron 2021. [DOI: 10.1016/j.poly.2020.114992] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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26
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Kataria R, Duhan N, Kaundal R. Computational Systems Biology of Alfalfa - Bacterial Blight Host-Pathogen Interactions: Uncovering the Complex Molecular Networks for Developing Durable Disease Resistant Crop. FRONTIERS IN PLANT SCIENCE 2021; 12:807354. [PMID: 35251063 PMCID: PMC8891223 DOI: 10.3389/fpls.2021.807354] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 12/29/2021] [Indexed: 05/04/2023]
Abstract
Medicago sativa (also known as alfalfa), a forage legume, is widely cultivated due to its high yield and high-value hay crop production. Infectious diseases are a major threat to the crops, owing to huge economic losses to the agriculture industry, worldwide. The protein-protein interactions (PPIs) between the pathogens and their hosts play a critical role in understanding the molecular basis of pathogenesis. Pseudomonas syringae pv. syringae ALF3 suppresses the plant's innate immune response by secreting type III effector proteins into the host cell, causing bacterial stem blight in alfalfa. The alfalfa-P. syringae system has little information available for PPIs. Thus, to understand the infection mechanism, we elucidated the genome-scale host-pathogen interactions (HPIs) between alfalfa and P. syringae using two computational approaches: interolog-based and domain-based method. A total of ∼14 M putative PPIs were predicted between 50,629 alfalfa proteins and 2,932 P. syringae proteins by combining these approaches. Additionally, ∼0.7 M consensus PPIs were also predicted. The functional analysis revealed that P. syringae proteins are highly involved in nucleotide binding activity (GO:0000166), intracellular organelle (GO:0043229), and translation (GO:0006412) while alfalfa proteins are involved in cellular response to chemical stimulus (GO:0070887), oxidoreductase activity (GO:0016614), and Golgi apparatus (GO:0005794). According to subcellular localization predictions, most of the pathogen proteins targeted host proteins within the cytoplasm and nucleus. In addition, we discovered a slew of new virulence effectors in the predicted HPIs. The current research describes an integrated approach for deciphering genome-scale host-pathogen PPIs between alfalfa and P. syringae, allowing the researchers to better understand the pathogen's infection mechanism and develop pathogen-resistant lines.
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Affiliation(s)
- Raghav Kataria
- Department of Plants, Soils, and Climate, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
| | - Naveen Duhan
- Department of Plants, Soils, and Climate, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
| | - Rakesh Kaundal
- Department of Plants, Soils, and Climate, College of Agriculture and Applied Sciences, Utah State University, Logan, UT, United States
- Bioinformatics Facility, Center for Integrated Biosystems, Utah State University, Logan, UT, United States
- Department of Computer Science, College of Science, Utah State University, Logan, UT, United States
- *Correspondence: Rakesh Kaundal, ;
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27
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Jørgensen JB, Djurhuus AM, Carstens AB, Kot W, Neve H, Morris CE, Hansen LH. Presentation of Three Novel Tailed Phages Targeting Multiple Strains of Pseudomonas syringae. PHAGE (NEW ROCHELLE, N.Y.) 2020; 1:245-250. [PMID: 36147285 PMCID: PMC9041480 DOI: 10.1089/phage.2020.0040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Background: Pseudomonas syringae are ubiquitous epiphytic plant pathogens infecting a wide range of important agricultural plant species. Bacteriophages has been proposed as biocontrol agents against plant pathogens, however, in order to utilize this approach, a deeper understanding of phage diversity and phage-host interactions is required. Materials and Methods: Phages targeting P. syringae GAW0113 were isolated from organic waste samples. Three distinct phage isolates were purified and subjected to whole-genome sequencing, comparative genomics, transmission electron microscopy and host-range assay using a wide selection of diverse P. syringae isolates. Results: The three phage isolates, Pseudomonas phage Bertil, Misse, and Strit, were shown to have podovirus morphology with a short tail stub and isometric head. They had double-stranded DNA ranging from 41,342 to 41,374 bp in size comprising 50-51 open reading frames. The three phage genomes were highly similar and genomic comparison analyses showed that they all belong to the Autographiviridae family of the order Caudovirales. All three phages were shown to have a narrow host-range. Conclusions: The three phages were shown to share morphological and genomic features with other phages in the Autographiviridae family, however, based on the limited nucleotide similarity we propose that the phages constitute a novel genus. All three phages were found to infect multiple strains of P. syringae covering several phylogroups.
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Affiliation(s)
- Jacob B. Jørgensen
- Department of Plant and Environmental Science, University of Copenhagen, Frederiksberg, Denmark
| | - Amaru M. Djurhuus
- Department of Plant and Environmental Science, University of Copenhagen, Frederiksberg, Denmark
| | - Alexander B. Carstens
- Department of Plant and Environmental Science, University of Copenhagen, Frederiksberg, Denmark
| | - Witold Kot
- Department of Plant and Environmental Science, University of Copenhagen, Frederiksberg, Denmark
| | - Horst Neve
- Department of Microbiology and Biotechnology, Max Rubner-Institut, Kiel, Germany
| | | | - Lars H. Hansen
- Department of Plant and Environmental Science, University of Copenhagen, Frederiksberg, Denmark
- Address correspondence to: Lars H. Hansen, PhD, Department of Plant and Environmental Science, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg 1871, Denmark
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28
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Oueslati M, Mulet M, Zouaoui M, Chandeysson C, Lalucat J, Hajlaoui MR, Berge O, García-Valdés E, Sadfi-Zouaoui N. Diversity of pathogenic Pseudomonas isolated from citrus in Tunisia. AMB Express 2020; 10:198. [PMID: 33130970 PMCID: PMC7604283 DOI: 10.1186/s13568-020-01134-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 10/21/2020] [Indexed: 11/12/2022] Open
Abstract
The damages observed in Tunisian citrus orchards have prompted studies on the Pseudomonas spp. responsible for blast and black pit. Prospective orchards between 2015 and 2017 showed that the diseases rapidly spread geographically and to new cultivars. A screening of Pseudomonas spp. isolated from symptomatic trees revealed their wide diversity according to phylogenetic analysis of their housekeeping rpoD and cts genes. The majority of strains were affiliated to Pseudomonas syringae pv. syringae (Phylogroup PG02b), previously described in Tunisia. However, they exhibited various BOX-PCR fingerprints and were not clonal. This work demonstrated, for the first time in Tunisia, the involvement of Pseudomonas cerasi (PG02a) and Pseudomonas congelans (PG02c). The latter did not show significant pathogenicity on citrus, but was pathogenic on cantaloupe and active for ice nucleation that could play a role in the disease. A comparative phylogenetic study of citrus pathogens from Iran, Montenegro and Tunisia revealed that P. syringae (PG02b) strains are closely related but again not clonal. Interestingly P. cerasi (PG02a) was isolated in two countries and seems to outspread. However, its role in the diseases is not fully understood and it should be monitored in future studies. The diversity of pathogenic Pseudomonas spp. and the extension of the diseases highlight that they have become complex and synergistic. It opens questions about which factors favor diseases and how to fight against them efficiently and with sustainable means.
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29
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Fones HN. Presence of ice-nucleating Pseudomonas on wheat leaves promotes Septoria tritici blotch disease (Zymoseptoria tritici) via a mutually beneficial interaction. Sci Rep 2020; 10:17738. [PMID: 33082401 PMCID: PMC7575590 DOI: 10.1038/s41598-020-74615-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 09/09/2020] [Indexed: 11/09/2022] Open
Abstract
Zymoseptoria tritici causes Septoria tritici blotch (STB) of wheat, an economically important disease causing yield losses of up to 10% despite the use of fungicides and resistant cultivars. Z. tritici infection is symptomless for around 10 days, during which time the fungus grows randomly across the leaf surface prior to entry through stomata. Wounded leaves show faster, more extensive STB, suggesting that wounds facilitate fungal entry. Wheat leaves also host epiphytic bacteria; these include ice-nucleating (INA+) bacteria, which induce frost damage at warmer temperatures than it otherwise occurs. Here, STB is shown to be more rapid and severe when wheat is exposed to both INA+ bacteria and sub-zero temperatures. This suggests that ice-nucleation-induced wounding of the wheat leaf provides additional openings for fungal entry. INA+ bacterial populations are shown to benefit from the presence of Z. tritici, indicating that this microbial interaction is mutualistic. Finally, control of INA+ bacteria is shown to reduce STB.
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Affiliation(s)
- Helen N Fones
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
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30
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Laachir A, Guesmi S, Ketatni EM, Saadi M, El Ammari L, Mentré O, Esserti S, Faize M, Bentiss F. A new homobimetallic cobalt(II) complex based on the tetradentate 3,5-bis(2-pyridyl)-1H-1,2,4-triazole ligand: Synthesis, crystal structure, Hirshfeld analysis, spectroscopic characterization, magnetic properties and antimicrobial activities. Polyhedron 2020. [DOI: 10.1016/j.poly.2020.114722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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31
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Helmann TC, Deutschbauer AM, Lindow SE. Distinctiveness of genes contributing to growth of Pseudomonas syringae in diverse host plant species. PLoS One 2020; 15:e0239998. [PMID: 32986776 PMCID: PMC7521676 DOI: 10.1371/journal.pone.0239998] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 09/16/2020] [Indexed: 12/04/2022] Open
Abstract
A variety of traits are necessary for bacterial colonization of the interior of plant hosts, including well-studied virulence effectors as well as other phenotypes contributing to bacterial growth and survival within the apoplast. High-throughput methods such as transposon sequencing (TnSeq) are powerful tools to identify such genes in bacterial pathogens. However, there is little information as to the distinctiveness of traits required for bacterial colonization of different hosts. Here, we utilize randomly barcoded TnSeq (RB-TnSeq) to identify the genes that contribute to the ability of Pseudomonas syringae strain B728a to grow within common bean (Phaseolus vulgaris), lima bean (Phaseolus lunatus), and pepper (Capsicum annuum); species representing two different plant families. The magnitude of contribution of most genes to apoplastic fitness in each of the plant hosts was similar. However, 50 genes significantly differed in their fitness contributions to growth within these species. These genes encoded proteins in various functional categories including polysaccharide synthesis and transport, amino acid metabolism and transport, cofactor metabolism, and phytotoxin synthesis and transport. Six genes that encoded unannotated, hypothetical proteins also contributed differentially to growth in these hosts. The genetic repertoire of a relatively promiscuous pathogen such as P. syringae may thus be shaped, at least in part, by the conditional contribution of some fitness determinants.
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Affiliation(s)
- Tyler C. Helmann
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
| | - Adam M. Deutschbauer
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Steven E. Lindow
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
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32
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Tarn MD, Sikora SNF, Porter GCE, Wyld BV, Alayof M, Reicher N, Harrison AD, Rudich Y, Shim JU, Murray BJ. On-chip analysis of atmospheric ice-nucleating particles in continuous flow. LAB ON A CHIP 2020; 20:2889-2910. [PMID: 32661539 DOI: 10.1039/d0lc00251h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ice-nucleating particles (INPs) are of atmospheric importance because they catalyse the freezing of supercooled cloud droplets, strongly affecting the lifetime and radiative properties of clouds. There is a need to improve our knowledge of the global distribution of INPs, their seasonal cycles and long-term trends, but our capability to make these measurements is limited. Atmospheric INP concentrations are often determined using assays involving arrays of droplets on a cold stage, but such assays are frequently limited by the number of droplets that can be analysed per experiment, often involve manual processing (e.g. pipetting of droplets), and can be susceptible to contamination. Here, we present a microfluidic platform, the LOC-NIPI (Lab-on-a-Chip Nucleation by Immersed Particle Instrument), for the generation of water-in-oil droplets and their freezing in continuous flow as they pass over a cold plate for atmospheric INP analysis. LOC-NIPI allows the user to define the number of droplets analysed by simply running the platform for as long as required. The use of small (∼100 μm diameter) droplets minimises the probability of contamination in any one droplet and therefore allows supercooling all the way down to homogeneous freezing (around -36 °C), while a temperature probe in a proxy channel provides an accurate measure of temperature without the need for temperature modelling. The platform was validated using samples of pollen extract and Snomax®, with hundreds of droplets analysed per temperature step and thousands of droplets being measured per experiment. Homogeneous freezing of purified water was studied using >10 000 droplets with temperature increments of 0.1 °C. The results were reproducible, independent of flow rate in the ranges tested, and the data compared well to conventional instrumentation and literature data. The LOC-NIPI was further benchmarked in a field campaign in the Eastern Mediterranean against other well-characterised instrumentation. The continuous flow nature of the system provides a route, with future development, to the automated monitoring of atmospheric INP at field sites around the globe.
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Affiliation(s)
- Mark D Tarn
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK. and School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
| | | | - Grace C E Porter
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK. and School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
| | - Bethany V Wyld
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK.
| | - Matan Alayof
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Reicher
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Yinon Rudich
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Jung-Uk Shim
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
| | - Benjamin J Murray
- School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK.
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Hulin MT, Jackson RW, Harrison RJ, Mansfield JW. Cherry picking by pseudomonads: After a century of research on canker, genomics provides insights into the evolution of pathogenicity towards stone fruits. PLANT PATHOLOGY 2020; 69:962-978. [PMID: 32742023 PMCID: PMC7386918 DOI: 10.1111/ppa.13189] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/09/2020] [Accepted: 03/23/2020] [Indexed: 05/10/2023]
Abstract
Bacterial canker disease is a major limiting factor in the growing of cherry and other Prunus species worldwide. At least five distinct clades within the bacterial species complex Pseudomonas syringae are known to be causal agents of the disease. The different pathogens commonly coexist in the field. Reducing canker is a challenging prospect as the efficacy of chemical controls and host resistance may vary against each of the diverse clades involved. Genomic analysis has revealed that the pathogens use a variable repertoire of virulence factors to cause the disease. Significantly, strains of P. syringae pv. syringae possess more genes for toxin biosynthesis and fewer encoding type III effector proteins. There is also a shared pool of key effector genes present on mobile elements such as plasmids and prophages that may have roles in virulence. By contrast, there is evidence that absence or truncation of certain effector genes, such as hopAB, is characteristic of cherry pathogens. Here we highlight how recent research, underpinned by the earlier epidemiological studies, is allowing significant progress in our understanding of the canker pathogens. This fundamental knowledge, combined with emerging insights into host genetics, provides the groundwork for development of precise control measures and informed approaches to breed for disease resistance.
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Affiliation(s)
| | - Robert W. Jackson
- Birmingham Institute of Forest Research (BIFoR), University of BirminghamBirminghamUK
- School of Biosciences, University of BirminghamBirminghamUK
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34
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Yadav AN, Singh J, Rastegari AA, Yadav N. Phyllospheric Microbiomes: Diversity, Ecological Significance, and Biotechnological Applications. ACTA ACUST UNITED AC 2020. [PMCID: PMC7123684 DOI: 10.1007/978-3-030-38453-1_5] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The phyllosphere referred to the total aerial plant surfaces (above-ground portions), as habitat for microorganisms. Microorganisms establish compositionally complex communities on the leaf surface. The microbiome of phyllosphere is rich in diversity of bacteria, fungi, actinomycetes, cyanobacteria, and viruses. The diversity, dispersal, and community development on the leaf surface are based on the physiochemistry, environment, and also the immunity of the host plant. A colonization process is an important event where both the microbe and the host plant have been benefited. Microbes commonly established either epiphytic or endophytic mode of life cycle on phyllosphere environment, which helps the host plant and functional communication with the surrounding environment. To the scientific advancement, several molecular techniques like metagenomics and metaproteomics have been used to study and understand the physiology and functional relationship of microbes to the host and its environment. Based on the available information, this chapter describes the basic understanding of microbiome in leaf structure and physiology, microbial interactions, especially bacteria, fungi, and actinomycetes, and their adaptation in the phyllosphere environment. Further, the detailed information related to the importance of the microbiome in phyllosphere to the host plant and their environment has been analyzed. Besides, biopotentials of the phyllosphere microbiome have been reviewed.
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Affiliation(s)
- Ajar Nath Yadav
- Department of Biotechnology, Eternal University, Baru Sahib, Himachal Pradesh India
| | - Joginder Singh
- Department of Microbiology, Lovely Professional University, Phagwara, Punjab India
| | | | - Neelam Yadav
- Gopi Nath PG College, Veer Bahadur Singh Purvanchal University, Ghazipur, Uttar Pradesh India
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Martel A, Lo T, Desveaux D, Guttman DS. A High-Throughput, Seedling Screen for Plant Immunity. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:394-401. [PMID: 31851574 DOI: 10.1094/mpmi-10-19-0295-ta] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
An understanding of how biological diversity affects plant-microbe interactions is becoming increasingly important, particularly with respect to components of the pathogen effector arsenal and the plant immune system. Although technological improvements have greatly advanced our ability to examine molecular sequences and interactions, relatively few advances have been made that facilitate high-throughput, in vivo pathology screens. Here, we present a high-throughput, microplate-based, nondestructive seedling pathology assay, and apply it to identify Arabidopsis thaliana effector-triggered immunity (ETI) responses against Pseudomonas syringae type III secreted effectors. The assay was carried out in a 48-well microplate format with spray inoculation, and disease symptoms were quantitatively recorded in a semiautomated manner, thereby greatly reducing both time and costs. The assay requires only slight modifications of common labware and uses no proprietary software. We validated the assay by recapitulating known ETI responses induced by P. syringae in Arabidopsis. We also demonstrated that we can quantitatively differentiate responses from a diversity of plant genotypes grown in the same microplate. Finally, we showed that the results obtained from our assay can be used to perform genome-wide association studies to identify host immunity genes, recapitulating results that have been independently obtained with mature plants.
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Affiliation(s)
- Alexandre Martel
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
| | - Timothy Lo
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada
| | - David S Guttman
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada
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36
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Moreno-Pérez A, Pintado A, Murillo J, Caballo-Ponce E, Tegli S, Moretti C, Rodríguez-Palenzuela P, Ramos C. Host Range Determinants of Pseudomonas savastanoi Pathovars of Woody Hosts Revealed by Comparative Genomics and Cross-Pathogenicity Tests. FRONTIERS IN PLANT SCIENCE 2020; 11:973. [PMID: 32714356 PMCID: PMC7343908 DOI: 10.3389/fpls.2020.00973] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/15/2020] [Indexed: 05/02/2023]
Abstract
The study of host range determinants within the Pseudomonas syringae complex is gaining renewed attention due to its widespread distribution in non-agricultural environments, evidence of large variability in intra-pathovar host range, and the emergence of new epidemic diseases. This requires the establishment of appropriate model pathosystems facilitating integration of phenotypic, genomic and evolutionary data. Pseudomonas savastanoi pv. savastanoi is a model pathogen of the olive tree, and here we report a closed genome of strain NCPPB 3335, plus draft genome sequences of three strains isolated from oleander (pv. nerii), ash (pv. fraxini) and broom plants (pv. retacarpa). We then conducted a comparative genomic analysis of these four new genomes plus 16 publicly available genomes, representing 20 strains of these four P. savastanoi pathovars of woody hosts. Despite overlapping host ranges, cross-pathogenicity tests using four plant hosts clearly separated these pathovars and lead to pathovar reassignment of two strains. Critically, these functional assays were pivotal to reconcile phylogeny with host range and to define pathovar-specific genes repertoires. We report a pan-genome of 7,953 ortholog gene families and a total of 45 type III secretion system effector genes, including 24 core genes, four genes exclusive of pv. retacarpa and several genes encoding pathovar-specific truncations. Noticeably, the four pathovars corresponded with well-defined genetic lineages, with core genome phylogeny and hierarchical clustering of effector genes closely correlating with pathogenic specialization. Knot-inducing pathovars encode genes absent in the canker-inducing pv. fraxini, such as those related to indole acetic acid, cytokinins, rhizobitoxine, and a bacteriophytochrome. Other pathovar-exclusive genes encode type I, type II, type IV, and type VI secretion system proteins, the phytotoxine phevamine A, a siderophore, c-di-GMP-related proteins, methyl chemotaxis proteins, and a broad collection of transcriptional regulators and transporters of eight different superfamilies. Our combination of pathogenicity analyses and genomics tools allowed us to correctly assign strains to pathovars and to propose a repertoire of host range-related genes in the P. syringae complex.
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Affiliation(s)
- Alba Moreno-Pérez
- Área de Genética, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, Spain
| | - Adrián Pintado
- Área de Genética, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, Spain
| | - Jesús Murillo
- Institute for Multidisciplinary Research in Applied Biology, Universidad Pública de Navarra, Mutilva Baja, Spain
- *Correspondence: Jesús Murillo, ; Cayo Ramos,
| | - Eloy Caballo-Ponce
- Área de Genética, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, Spain
| | - Stefania Tegli
- Dipartimento di Scienze e Tecnologie Agrarie, Alimentari Ambientali e Forestali (DAGRI), Laboratorio di Patologia Vegetale Molecolare, University of Florence, Firenze, Italy
| | - Chiaraluce Moretti
- Department of Agricultural, Food and Environmental Science, University of Perugia, Perugia, Italy
| | - Pablo Rodríguez-Palenzuela
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, UPM, Madrid, Spain
| | - Cayo Ramos
- Área de Genética, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, Spain
- *Correspondence: Jesús Murillo, ; Cayo Ramos,
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Nogales J, Mueller J, Gudmundsson S, Canalejo FJ, Duque E, Monk J, Feist AM, Ramos JL, Niu W, Palsson BO. High-quality genome-scale metabolic modelling of Pseudomonas putida highlights its broad metabolic capabilities. Environ Microbiol 2019; 22:255-269. [PMID: 31657101 PMCID: PMC7078882 DOI: 10.1111/1462-2920.14843] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/27/2019] [Accepted: 10/23/2019] [Indexed: 12/19/2022]
Abstract
Genome-scale reconstructions of metabolism are computational species-specific knowledge bases able to compute systemic metabolic properties. We present a comprehensive and validated reconstruction of the biotechnologically relevant bacterium Pseudomonas putida KT2440 that greatly expands computable predictions of its metabolic states. The reconstruction represents a significant reactome expansion over available reconstructed bacterial metabolic networks. Specifically, iJN1462 (i) incorporates several hundred additional genes and associated reactions resulting in new predictive capabilities, including new nutrients supporting growth; (ii) was validated by in vivo growth screens that included previously untested carbon (48) and nitrogen (41) sources; (iii) yielded gene essentiality predictions showing large accuracy when compared with a knock-out library and Bar-seq data; and (iv) allowed mapping of its network to 82 P. putida sequenced strains revealing functional core that reflect the large metabolic versatility of this species, including aromatic compounds derived from lignin. Thus, this study provides a thoroughly updated metabolic reconstruction and new computable phenotypes for P. putida, which can be leveraged as a first step toward understanding the pan metabolic capabilities of Pseudomonas.
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Affiliation(s)
- Juan Nogales
- Department of Systems Biology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.,Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Joshua Mueller
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.,Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | | | - Francisco J Canalejo
- Department of Systems Biology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Estrella Duque
- Department of Environmental Protection, Estación Experimental del Zaidín (CSIC), Granada, Spain
| | - Jonathan Monk
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Adam M Feist
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Juan Luis Ramos
- Department of Environmental Protection, Estación Experimental del Zaidín (CSIC), Granada, Spain
| | - Wei Niu
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Bernhard O Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
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Baloh P, Els N, David RO, Larose C, Whitmore K, Sattler B, Grothe H. Assessment of Artificial and Natural Transport Mechanisms of Ice Nucleating Particles in an Alpine Ski Resort in Obergurgl, Austria. Front Microbiol 2019; 10:2278. [PMID: 31636618 PMCID: PMC6788259 DOI: 10.3389/fmicb.2019.02278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 09/18/2019] [Indexed: 01/31/2023] Open
Abstract
Artificial snow production is a crucial part of modern skiing resorts in Austria and globally, and will develop even more so with changing precipitation patterns and a warming climate trend. Producing artificial snow requires major investments in energy, water, infrastructure and manpower for skiing resorts. In addition to appropriate meteorological conditions, the efficiency of artificial snow production depends on heterogeneous ice-nucleation, which can occur at temperatures as high as -2°C when induced by specific bacterial ice nucleating particles (INPs). We aimed to investigate the presence, source and ice nucleating properties of these particles in the water cycle of an alpine ski resort in Obergurgl, Tyrol, Austria. We sampled artificial snow, river water, water pumped from a storage pond and compared it to samples collected from fresh natural snow and aged piste snow from the area. Particles from each sampled system were characterized in order to determine their transport mechanisms at a ski resort. We applied a physical droplet freezing assay [DRoplet Ice Nuclei Counter Zurich (DRINCZ)] to heated and unheated samples to characterize the biological and non-biological component of IN-activity. Bacterial abundance and community structure of the samples was obtained using quantitative PCR and Illumina Mi-Seq Amplicon Sequencing, and their chemical properties were determined by liquid ion-chromatography, energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). The results show the flow of biological and inorganic material from the river to the slopes, an uptake of new microorganisms through the air and the piping, and possible proliferation or introduction of ice nucleation active biological particles in aged piste snow. Natural snow, as the first stage in this system, had the lowest amount of ice nucleation active particles and the least amount of biological and mineral particles in general, yet shares some microbial characteristics with fresh artificial snow.
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Affiliation(s)
- Philipp Baloh
- Institute for Materials Chemistry, TU Wien, Vienna, Austria
| | - Nora Els
- Lake and Glacier Research Group, Institute of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Robert O David
- Institute for Atmospheric and Climate Science, ETH Zürich, Zurich, Switzerland
| | - Catherine Larose
- Laboratoire Ampère, Environmental Microbial Genomics, École Centrale de Lyon, Université de Lyon, Écully, France
| | - Karin Whitmore
- University Service Center for Transmission Electron Microscopy, TU Wien, Vienna, Austria
| | - Birgit Sattler
- Lake and Glacier Research Group, Institute of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Hinrich Grothe
- Institute for Materials Chemistry, TU Wien, Vienna, Austria
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Genome-wide identification of Pseudomonas syringae genes required for fitness during colonization of the leaf surface and apoplast. Proc Natl Acad Sci U S A 2019; 116:18900-18910. [PMID: 31484768 DOI: 10.1073/pnas.1908858116] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The foliar plant pathogen Pseudomonas syringae can establish large epiphytic populations on leaf surfaces before apoplastic colonization. However, the bacterial genes that contribute to these lifestyles have not been completely defined. The fitness contributions of 4,296 genes in P. syringae pv. syringae B728a were determined by genome-wide fitness profiling with a randomly barcoded transposon mutant library that was grown on the leaf surface and in the apoplast of the susceptible plant Phaseolus vulgaris Genes within the functional categories of amino acid and polysaccharide (including alginate) biosynthesis contributed most to fitness both on the leaf surface (epiphytic) and in the leaf interior (apoplast), while genes involved in type III secretion system and syringomycin synthesis were primarily important in the apoplast. Numerous other genes that had not been previously associated with in planta growth were also required for maximum epiphytic or apoplastic fitness. Fourteen hypothetical proteins and uncategorized glycosyltransferases were also required for maximum competitive fitness in and on leaves. For most genes, no relationship was seen between fitness in planta and either the magnitude of their expression in planta or degree of induction in planta compared to in vitro conditions measured in other studies. A lack of association of gene expression and fitness has important implications for the interpretation of transcriptional information and our broad understanding of plant-microbe interactions.
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40
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Gerin D, Cariddi C, de Miccolis Angelini RM, Rotolo C, Dongiovanni C, Faretra F, Pollastro S. First Report of Pseudomonas Grapevine Bunch Rot Caused by Pseudomonas syringae pv. syringae. PLANT DISEASE 2019; 103:1954-1960. [PMID: 31169085 DOI: 10.1094/pdis-11-18-1992-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pseudomonas syringae pv. syringae, a Gammaproteobacterium belonging to genomospecies 2 within the P. syringae complex, is distributed worldwide, and it is responsible for bacterial canker on >100 different hosts, including the grapevine. P. syringae pv. syringae induces necrotic lesions in the leaf blades, veins, petioles, shoots, rachis, and tendrils on grapevine cultivars in different areas. P. syringae pv. syringae has been associated with severe economic losses in different grape cultivars in Australia, where it causes inflorescence rot. In midsummer to late summer 2017, symptoms of berry rots differing from those caused by the common berry rots agents were observed in different cultivar Red Globe vineyards of Apulia (southern Italy). As proven by fulfillment of Koch's postulates, these symptoms were caused by a bacterium that, according to the results of biochemical, physiological, nutritional, antimicrobial activity, and pathogenicity tests and sequencing of 16S ribosomal DNA, gyrB, rpoB, and rpoD genes, was identified as P. syringae pv. syringae. This is the first report of Pseudomonas grapevine bunch rot.
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Affiliation(s)
- D Gerin
- 1Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, 70126 Bari, Italy
| | - C Cariddi
- 1Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, 70126 Bari, Italy
| | - R M de Miccolis Angelini
- 1Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, 70126 Bari, Italy
- 2Selge Network, University of Bari Aldo Moro, 70126 Bari, Italy
| | - C Rotolo
- 1Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, 70126 Bari, Italy
| | - C Dongiovanni
- 3Centro di Ricerca, Sperimentazione e Formazione in Agricoltura "Basile Caramia," 70010 Locorotondo, Italy
| | - F Faretra
- 1Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, 70126 Bari, Italy
- 2Selge Network, University of Bari Aldo Moro, 70126 Bari, Italy
| | - S Pollastro
- 1Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, 70126 Bari, Italy
- 2Selge Network, University of Bari Aldo Moro, 70126 Bari, Italy
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Dillon MM, Almeida RN, Laflamme B, Martel A, Weir BS, Desveaux D, Guttman DS. Molecular Evolution of Pseudomonas syringae Type III Secreted Effector Proteins. FRONTIERS IN PLANT SCIENCE 2019; 10:418. [PMID: 31024592 PMCID: PMC6460904 DOI: 10.3389/fpls.2019.00418] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/19/2019] [Indexed: 05/02/2023]
Abstract
Diverse Gram-negative pathogens like Pseudomonas syringae employ type III secreted effector (T3SE) proteins as primary virulence factors that combat host immunity and promote disease. T3SEs can also be recognized by plant hosts and activate an effector triggered immune (ETI) response that shifts the interaction back toward plant immunity. Consequently, T3SEs are pivotal in determining the virulence potential of individual P. syringae strains, and ultimately help to restrict P. syringae pathogens to a subset of potential hosts that are unable to recognize their repertoires of T3SEs. While a number of effector families are known to be present in the P. syringae species complex, one of the most persistent challenges has been documenting the complex variation in T3SE contents across a diverse collection of strains. Using the entire pan-genome of 494 P. syringae strains isolated from more than 100 hosts, we conducted a global analysis of all known and putative T3SEs. We identified a total of 14,613 putative T3SEs, 4,636 of which were unique at the amino acid level, and show that T3SE repertoires of different P. syringae strains vary dramatically, even among strains isolated from the same hosts. We also find substantial diversification within many T3SE families, and in many cases find strong signatures of positive selection. Furthermore, we identify multiple gene gain and loss events for several families, demonstrating an important role of horizontal gene transfer (HGT) in the evolution of P. syringae T3SEs. These analyses provide insight into the evolutionary history of P. syringae T3SEs as they co-evolve with the host immune system, and dramatically expand the database of P. syringae T3SEs alleles.
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Affiliation(s)
- Marcus M. Dillon
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Renan N.D. Almeida
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Bradley Laflamme
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Alexandre Martel
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
| | | | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON, Canada
| | - David S. Guttman
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON, Canada
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Ruinelli M, Blom J, Smits THM, Pothier JF. Comparative genomics and pathogenicity potential of members of the Pseudomonas syringae species complex on Prunus spp. BMC Genomics 2019; 20:172. [PMID: 30836956 PMCID: PMC6402114 DOI: 10.1186/s12864-019-5555-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 02/22/2019] [Indexed: 11/22/2022] Open
Abstract
Background Diseases on Prunus spp. have been associated with a large number of phylogenetically different pathovars and species within the P. syringae species complex. Despite their economic significance, there is a severe lack of genomic information of these pathogens. The high phylogenetic diversity observed within strains causing disease on Prunus spp. in nature, raised the question whether other strains or species within the P. syringae species complex were potentially pathogenic on Prunus spp. Results To gain insight into the genomic potential of adaptation and virulence in Prunus spp., a total of twelve de novo whole genome sequences of P. syringae pathovars and species found in association with diseases on cherry (sweet, sour and ornamental-cherry) and peach were sequenced. Strains sequenced in this study covered three phylogroups and four clades. These strains were screened in vitro for pathogenicity on Prunus spp. together with additional genome sequenced strains thus covering nine out of thirteen of the currently defined P. syringae phylogroups. Pathogenicity tests revealed that most of the strains caused symptoms in vitro and no obvious link was found between presence of known virulence factors and the observed pathogenicity pattern based on comparative genomics. Non-pathogenic strains were displaying a two to three times higher generation time when grown in rich medium. Conclusion In this study, the first set of complete genomes of cherry associated P. syringae strains as well as the draft genome of the quarantine peach pathogen P. syringae pv. persicae were generated. The obtained genomic data were matched with phenotypic data in order to determine factors related to pathogenicity to Prunus spp. Results of this study suggest that the inability to cause disease on Prunus spp. in vitro is not the result of host specialization but rather linked to metabolic impairments of individual strains. Electronic supplementary material The online version of this article (10.1186/s12864-019-5555-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michela Ruinelli
- Environmental Genomics and Systems Biology Research Group, Institute for Natural Resources Sciences, Zurich University of Applied Sciences, CH-8820, Wädenswil, Switzerland
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, 35392, Giessen, Germany
| | - Theo H M Smits
- Environmental Genomics and Systems Biology Research Group, Institute for Natural Resources Sciences, Zurich University of Applied Sciences, CH-8820, Wädenswil, Switzerland.
| | - Joël F Pothier
- Environmental Genomics and Systems Biology Research Group, Institute for Natural Resources Sciences, Zurich University of Applied Sciences, CH-8820, Wädenswil, Switzerland
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Newberry EA, Ebrahim M, Timilsina S, Zlatković N, Obradović A, Bull CT, Goss EM, Huguet-Tapia JC, Paret ML, Jones JB, Potnis N. Inference of Convergent Gene Acquisition Among Pseudomonas syringae Strains Isolated From Watermelon, Cantaloupe, and Squash. Front Microbiol 2019; 10:270. [PMID: 30837979 PMCID: PMC6390507 DOI: 10.3389/fmicb.2019.00270] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/01/2019] [Indexed: 01/01/2023] Open
Abstract
Pseudomonas syringae sensu stricto (phylogroup 2; referred to as P. syringae) consists of an environmentally ubiquitous bacterial population associated with diseases of numerous plant species. Recent studies using multilocus sequence analysis have indicated the clonal expansion of several P. syringae lineages, located in phylogroups 2a and 2b, in association with outbreaks of bacterial spot disease of watermelon, cantaloupe, and squash in the United States. To investigate the evolutionary processes that led to the emergence of these epidemic lineages, we sequenced the genomes of six P. syringae strains that were isolated from cucurbits grown in the United States, Europe, and China over a period of more than a decade, as well as eight strains that were isolated from watermelon and squash grown in six different Florida counties during the 2013 and 2014 seasons. These data were subjected to comparative analyses along with 42 previously sequenced genomes of P. syringae stains collected from diverse plant species and environments available from GenBank. Maximum likelihood reconstruction of the P. syringae core genome revealed the presence of a hybrid phylogenetic group, comprised of cucurbit strains collected in Florida, Italy, Serbia, and France, which emerged through genome-wide homologous recombination between phylogroups 2a and 2b. Functional analysis of the recombinant core genome showed that pathways involved in the ATP-dependent transport and metabolism of amino acids, bacterial motility, and secretion systems were enriched for recombination. A survey of described virulence factors indicated the convergent acquisition of several accessory type 3 secreted effectors (T3SEs) among phylogenetically distinct lineages through integrative and conjugative element and plasmid loci. Finally, pathogenicity assays on watermelon and squash showed qualitative differences in virulence between strains of the same clonal lineage, which correlated with T3SEs acquired through various mechanisms of horizontal gene transfer (HGT). This study provides novel insights into the interplay of homologous recombination and HGT toward pathogen emergence and highlights the dynamic nature of P. syringae sensu lato genomes.
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Affiliation(s)
- Eric A Newberry
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, United States.,Department of Plant Pathology, North Florida Research and Education Center, University of Florida, Quincy, FL, United States
| | - Mohamed Ebrahim
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States.,Department of Plant Pathology, Faculty of Agriculture, Ain Shams University, Cairo, Egypt
| | - Sujan Timilsina
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
| | - Nevena Zlatković
- Faculty of Agriculture, University of Belgrade, Belgrade, Serbia
| | - Aleksa Obradović
- Faculty of Agriculture, University of Belgrade, Belgrade, Serbia
| | - Carolee T Bull
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, State College, PA, United States
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
| | - Jose C Huguet-Tapia
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
| | - Mathews L Paret
- Department of Plant Pathology, North Florida Research and Education Center, University of Florida, Quincy, FL, United States
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, United States
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, United States
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Bardaji L, Añorga M, Echeverría M, Ramos C, Murillo J. The toxic guardians - multiple toxin-antitoxin systems provide stability, avoid deletions and maintain virulence genes of Pseudomonas syringae virulence plasmids. Mob DNA 2019; 10:7. [PMID: 30728866 PMCID: PMC6354349 DOI: 10.1186/s13100-019-0149-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/18/2019] [Indexed: 02/05/2023] Open
Abstract
Background Pseudomonas syringae is a γ-proteobacterium causing economically relevant diseases in practically all cultivated plants. Most isolates of this pathogen contain native plasmids collectively carrying many pathogenicity and virulence genes. However, P. syringae is generally an opportunistic pathogen primarily inhabiting environmental reservoirs, which could exert a low selective pressure for virulence plasmids. Additionally, these plasmids usually contain a large proportion of repeated sequences, which could compromise plasmid integrity. Therefore, the identification of plasmid stability determinants and mechanisms to preserve virulence genes is essential to understand the evolution of this pathogen and its adaptability to agroecosystems. Results The three virulence plasmids of P. syringae pv. savastanoi NCPPB 3335 contain from one to seven functional stability determinants, including three highly active toxin-antitoxin systems (TA) in both pPsv48A and pPsv48C. The TA systems reduced loss frequency of pPsv48A by two orders of magnitude, whereas one of the two replicons of pPsv48C likely confers stable inheritance by itself. Notably, inactivation of the TA systems from pPsv48C exposed the plasmid to high-frequency deletions promoted by mobile genetic elements. Thus, recombination between two copies of MITEPsy2 caused the deletion of an 8.3 kb fragment, with a frequency of 3.8 ± 0.3 × 10− 3. Likewise, one-ended transposition of IS801 generated plasmids containing deletions of variable size, with a frequency of 5.5 ± 2.1 × 10− 4, of which 80% had lost virulence gene idi. These deletion derivatives were stably maintained in the population by replication mediated by repJ, which is adjacent to IS801. IS801 also promoted deletions in plasmid pPsv48A, either by recombination or one-ended transposition. In all cases, functional TA systems contributed significantly to reduce the occurrence of plasmid deletions in vivo. Conclusions Virulence plasmids from P. syringae harbour a diverse array of stability determinants with a variable contribution to plasmid persistence. Importantly, we showed that multiple plasmid-borne TA systems have a prominent role in preserving plasmid integrity and ensuring the maintenance of virulence genes in free-living conditions. This strategy is likely widespread amongst native plasmids of P. syringae and other bacteria. Electronic supplementary material The online version of this article (10.1186/s13100-019-0149-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Leire Bardaji
- 1Institute for Multidisciplinary Applied Biology, Universidad Pública de Navarra, 31192 Mutilva, Spain
| | - Maite Añorga
- 1Institute for Multidisciplinary Applied Biology, Universidad Pública de Navarra, 31192 Mutilva, Spain
| | - Myriam Echeverría
- 1Institute for Multidisciplinary Applied Biology, Universidad Pública de Navarra, 31192 Mutilva, Spain
| | - Cayo Ramos
- 2Instituto de Hortofruticultura Subtropical y Mediterránea «La Mayora», Universidad de Málaga-CSIC, Área de Genética, Universidad de Málaga, Campus de Teatinos s/n, 29010 Málaga, Spain
| | - Jesús Murillo
- 1Institute for Multidisciplinary Applied Biology, Universidad Pública de Navarra, 31192 Mutilva, Spain
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Recombination of ecologically and evolutionarily significant loci maintains genetic cohesion in the Pseudomonas syringae species complex. Genome Biol 2019; 20:3. [PMID: 30606234 PMCID: PMC6317194 DOI: 10.1186/s13059-018-1606-y] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 12/06/2018] [Indexed: 01/25/2023] Open
Abstract
Background Pseudomonas syringae is a highly diverse bacterial species complex capable of causing a wide range of serious diseases on numerous agronomically important crops. We examine the evolutionary relationships of 391 agricultural and environmental strains using whole-genome sequencing and evolutionary genomic analyses. Results We describe the phylogenetic distribution of all 77,728 orthologous gene families in the pan-genome, reconstruct the core genome phylogeny using the 2410 core genes, hierarchically cluster the accessory genome, identify the diversity and distribution of type III secretion systems and their effectors, predict ecologically and evolutionary relevant loci, and establish the molecular evolutionary processes operating on gene families. Phylogenetic and recombination analyses reveals that the species complex is subdivided into primary and secondary phylogroups, with the former primarily comprised of agricultural isolates, including all of the well-studied P. syringae strains. In contrast, the secondary phylogroups include numerous environmental isolates. These phylogroups also have levels of genetic diversity typically found among distinct species. An analysis of rates of recombination within and between phylogroups revealed a higher rate of recombination within primary phylogroups than between primary and secondary phylogroups. We also find that “ecologically significant” virulence-associated loci and “evolutionarily significant” loci under positive selection are over-represented among loci that undergo inter-phylogroup genetic exchange. Conclusions While inter-phylogroup recombination occurs relatively rarely, it is an important force maintaining the genetic cohesion of the species complex, particularly among primary phylogroup strains. This level of genetic cohesion, and the shared plant-associated niche, argues for considering the primary phylogroups as a single biological species. Electronic supplementary material The online version of this article (10.1186/s13059-018-1606-y) contains supplementary material, which is available to authorized users.
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Bardin M, Leyronas C, Troulet C, Morris CE. Striking Similarities Between Botrytis cinerea From Non-agricultural and From Agricultural Habitats. FRONTIERS IN PLANT SCIENCE 2018; 9:1820. [PMID: 30568671 PMCID: PMC6290265 DOI: 10.3389/fpls.2018.01820] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 11/22/2018] [Indexed: 06/09/2023]
Abstract
Investigations into life history of microorganisms that cause plant diseases have been limited mostly to contexts where they are in interaction with plants, and with cropped or otherwise managed vegetation. Therefore, knowledge about the diversity of plant pathogens, about potential reservoirs of inoculum and about the processes that contribute to their survival and adaptation is limited to these contexts. The agro-centric perspective of plant pathogen life histories is incoherent with respect to the capacity of many of them to persist as saprophytes on various substrates. In this context we have investigated the ubiquity of the broad host range necrotrophic fungus Botrytis cinerea, outside of agricultural settings and have determined if the populations in these natural habitats can be distinguished phenotypically and phylogenetically from populations isolated from diseased crops. Over a period of 5 years, we isolated B. cinerea from 235 samples of various substrates collected in France including rainfall, snowpack, river, and lake water, epilithic biofilms in mountain streams, leaf litter and plant debris, rock surfaces, bird feathers and healthy wild plants from outside of agricultural fields. All substrates except rock surfaces harbored B. cinerea leading us to establish a collection of purified strains that were compared to B. cinerea from diseased tomato, grapes and various other crops in France. Phylogenetic comparisons of 321 strains from crop plants and 100 strains from environmental substrates based on sequences of 9 microsatellite markers revealed that strains from crops and the environment could not be distinguished. Furthermore, the genetic diversity of strains outside of agriculture was just as broad as within agriculture. In tests to determine the aggressiveness of strains on tomato stems, the mean disease severity caused by strains from environmental substrates was statistically identical to the severity of disease caused by strains from tomato, but was significantly greater than the severity caused by strains from grape or other crops. Our results suggest that highly diverse populations of this plant pathogen persist outside of agriculture in association with substrates other than plants and that this part of their life history is compatible with its capacity to maintain its potential as plant pathogen.
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Affiliation(s)
- Marc Bardin
- Pathologie Végétale, INRA, Montfavet, France
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Arnold DL, Preston GM. Pseudomonas syringae: enterprising epiphyte and stealthy parasite. MICROBIOLOGY-SGM 2018; 165:251-253. [PMID: 30427303 DOI: 10.1099/mic.0.000715] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Pseudomonas syringae is best known as a plant pathogenic bacterium that causes diseases in a multitude of hosts, and it has been used as a model organism to understand the biology of plant disease. Pathogenic and non-pathogenic isolates of P. syringae are also commonly found living as epiphytes and in the wider environment, including water sources such as rivers and precipitation. Ice-nucleating strains of P. syringae are associated with frost damage to crops. The genomes of numerous strains of P. syringae have been sequenced and molecular genetic studies have elucidated many aspects of this pathogen's interaction with its host plants.
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Affiliation(s)
- Dawn L Arnold
- 1Centre for Research in Bioscience, Faculty of Health and Applied Sciences, The University of the West of England, Frenchay Campus, Bristol BS16 1QY, UK
| | - Gail M Preston
- 2Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
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Matilla MA, Krell T. The effect of bacterial chemotaxis on host infection and pathogenicity. FEMS Microbiol Rev 2018; 42:4563582. [PMID: 29069367 DOI: 10.1093/femsre/fux052] [Citation(s) in RCA: 152] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 10/19/2017] [Indexed: 12/26/2022] Open
Abstract
Chemotaxis enables microorganisms to move according to chemical gradients. Although this process requires substantial cellular energy, it also affords key physiological benefits, including enhanced access to growth substrates. Another important implication of chemotaxis is that it also plays an important role in infection and disease, as chemotaxis signalling pathways are broadly distributed across a variety of pathogenic bacteria. Furthermore, current research indicates that chemotaxis is essential for the initial stages of infection in different human, animal and plant pathogens. This review focuses on recent findings that have identified specific bacterial chemoreceptors and corresponding chemoeffectors associated with pathogenicity. Pathogenicity-related chemoeffectors are either host and niche-specific signals or intermediates of the host general metabolism. Plant pathogens were found to contain an elevated number of chemotaxis signalling genes and functional studies demonstrate that these genes are critical for their ability to enter the host. The expanding body of knowledge of the mechanisms underlying chemotaxis in pathogens provides a foundation for the development of new therapeutic strategies capable of blocking infection and preventing disease by interfering with chemotactic signalling pathways.
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Affiliation(s)
- Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, 18008 Granada, Spain
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Marcelletti S, Scortichini M. Some strains that have converged to infect Prunus spp. trees are members of distinct Pseudomonas syringae genomospecies and ecotypes as revealed by in silico genomic comparison. Arch Microbiol 2018; 201:67-80. [PMID: 30229267 DOI: 10.1007/s00203-018-1573-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 09/06/2018] [Accepted: 09/13/2018] [Indexed: 11/29/2022]
Abstract
A complementary taxonomic and population genetic study was performed to delineate genetically and ecologically distinct species within the Pseudomonas syringae complex by assessing 16 strains including pathovar strains that have converged to infect Prunus spp. trees, and two outgroups. Both average nucleotide identity and genome-to-genome distance comparison methods revealed the occurrence of distinct genomospecies, namely 1, 2, 3 and 8 (sensu Gardan et al.), with the latter two being closely related. Strains classified as P. s. pv. morsprunorum clustered into two distinct genomospecies, namely 2 and 8. Both the AdaptML and hierarchical Bayesian analysis of population structure methods highlighted the presence of three ecotypes, and the taxonomically related genomospecies 3 and 8 strains were members of the same ecotype. The distribution of pathogenic and virulence-associated genetic traits among Pseudomonas strains did not reveal any distinct type III secretion system effector or phytotoxin distribution pattern that characterized single genomospecies and strains that infect Prunus spp. The complete WHOP (Woody HOst and Pseudomonas spp.) genomic region and the entire β-ketoadipate gene cluster, including the catBCA operon, were found only in the members of genomospecies 2 and in the two P. s. pv. morsprunorum strains of genomospecies 8. A reduced gene flow between the three ecotypes suggested that point mutations played a larger role during the evolution of the strains than recombination. Our data support the idea that Prunus trees can be infected by different strains of distinct Pseudomonas genomospecies/ecotypes through diverse mechanisms of host colonization and infection. Such strains may represent particular lineages that emerged from environments other than that of the infected plant upon acquiring genetic traits that gave them the ability to cause plant diseases. The complementary assessment of bacterial strains using both taxonomic approaches and methods that reveal ecologically homogeneous populations has proven useful in confirming the cohesion of bacterial clusters.
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Affiliation(s)
- Simone Marcelletti
- Council for Agricultural Research and Analysis of Agricultural Economics (CREA), Research Centre for Olive, Fruit Trees and Citrus, Via di Fioranello, 52, 00134, Rome, Italy
| | - Marco Scortichini
- Council for Agricultural Research and Analysis of Agricultural Economics (CREA), Research Centre for Olive, Fruit Trees and Citrus, Via di Fioranello, 52, 00134, Rome, Italy.
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Jimenez-Sanchez C, Hanlon R, Aho KA, Powers C, Morris CE, Schmale DG. Diversity and Ice Nucleation Activity of Microorganisms Collected With a Small Unmanned Aircraft System (sUAS) in France and the United States. Front Microbiol 2018; 9:1667. [PMID: 30158903 PMCID: PMC6104180 DOI: 10.3389/fmicb.2018.01667] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 07/04/2018] [Indexed: 11/13/2022] Open
Abstract
Many microbes relevant to crops, domestic animals, and humans are transported over long distances through the atmosphere. Some of these atmospheric microbes catalyze the freezing of water at higher temperatures and facilitate the onset of precipitation. We collected microbes from the lower atmosphere in France and the United States with a small unmanned aircraft system (sUAS). 55 sampling missions were conducted at two locations in France in 2014 (an airfield in Pujaut, and the top of Puy de Dôme), and three locations in the U.S. in 2015 (a farm in Blacksburg, Virginia, and a farm and a lake in Baton Rouge, Louisiana). The sUAS was a fixed-wing electric drone equipped with a remote-operated sampling device that was opened once the aircraft reached the desired sampling altitude (40-50 meters above ground level). Samples were collected on agar media (TSA, R4A, R2A, and CA) with and without the fungicide cycloheximide. Over 4,000 bacterial-like colonies were recovered across the 55 sUAS sampling missions. A positive relationship between sampling time and temperature and concentrations of culturable bacteria was observed for sUAS flights conducted in France, but not for sUAS flights conducted in Louisiana. A droplet freezing assay was used to screen nearly 2,000 colonies for ice nucleation activity, and 15 colonies were ice nucleation active at temperatures warmer than -8°C. Sequences from portions of 16S rDNA were used to identify 503 colonies from 54 flights to the level of genus. Assemblages of bacteria from sUAS flights in France (TSA) and sUAS flights in Louisiana (R4A) showed more similarity within locations than between locations. Bacteria collected with sUAS on TSA in France and Virginia were significantly different across all levels of classification tested (P < 0.001 for class, order, family, and genus). Principal Coordinates Analysis showed a strong association between the genera Curtobacterium, Pantoea, and Pseudomonas from sUAS flights in Virginia, and Agrococcus, Lysinibacillus, and Paenibacillus from sUAS flights in France. Future work aims to understand the potential origin of the atmospheric microbial assemblages collected with sUAS, and their association with mesoscale atmospheric processes.
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Affiliation(s)
- Celia Jimenez-Sanchez
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, United States
| | - Regina Hanlon
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, United States
| | - Ken A. Aho
- Department of Biological Sciences, Idaho State University, Pocatello, ID, United States
| | - Craig Powers
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, United States
| | - Cindy E. Morris
- INRA, Plant Pathology Research Unit, Provence Alpes Côtes d'Azur Research Center, Montfavet, France
| | - David G. Schmale
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, United States
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