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Baltrus DA, Clark M, Smith C, Hockett KL. Localized recombination drives diversification of killing spectra for phage-derived syringacins. THE ISME JOURNAL 2019; 13:237-249. [PMID: 30171255 PMCID: PMC6331570 DOI: 10.1038/s41396-018-0261-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 05/16/2018] [Accepted: 07/06/2018] [Indexed: 02/07/2023]
Abstract
To better understand the potential for antagonistic interactions between members of the same bacterial species, we have surveyed bacteriocin killing activity across a diverse suite of strains of the phytopathogen Pseudomonas syringae. Our data demonstrate that killing activity from phage-derived bacteriocins of P. syringae (R-type syringacins) is widespread. Despite a high overall diversity of bacteriocin activity, strains can broadly be classified into five main killing types and two main sensitivity types. Furthermore, we show that killing activity switches frequently between strains and that switches correlate with localized recombination of two genes that together encode the proteins that specify bacteriocin targeting. Lastly, we demonstrate that phage-derived bacteriocin killing activity can be swapped between strains simply through expression of these two genes in trans. Overall, our study characterizes extensive diversity of killing activity for phage-derived bacteriocins of P. syringae across strains and highlights the power of localized recombination to alter phenotypes that mediate strain interactions during evolution of natural populations and communities.
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Affiliation(s)
- David A Baltrus
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA.
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, 85721, USA.
| | - Meara Clark
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | - Caitlin Smith
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | - Kevin L Hockett
- Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, PA, 16802, USA
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
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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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Tahir J, Hoyte S, Bassett H, Brendolise C, Chatterjee A, Templeton K, Deng C, Crowhurst R, Montefiori M, Morgan E, Wotton A, Funnell K, Wiedow C, Knaebel M, Hedderley D, Vanneste J, McCallum J, Hoeata K, Nath A, Chagné D, Gea L, Gardiner SE. Multiple quantitative trait loci contribute to resistance to bacterial canker incited by Pseudomonas syringae pv. actinidiae in kiwifruit ( Actinidia chinensis). HORTICULTURE RESEARCH 2019; 6:101. [PMID: 31645956 PMCID: PMC6804790 DOI: 10.1038/s41438-019-0184-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 07/11/2019] [Accepted: 07/17/2019] [Indexed: 05/10/2023]
Abstract
Pseudomonas syringae pv. actinidiae (Psa) biovar 3, a virulent, canker-inducing pathogen is an economic threat to the kiwifruit (Actinidia spp.) industry worldwide. The commercially grown diploid (2×) A. chinensis var. chinensis is more susceptible to Psa than tetraploid and hexaploid kiwifruit. However information on the genetic loci modulating Psa resistance in kiwifruit is not available. Here we report mapping of quantitative trait loci (QTLs) regulating resistance to Psa in a diploid kiwifruit population, derived from a cross between an elite Psa-susceptible 'Hort16A' and a resistant male breeding parent P1. Using high-density genetic maps and intensive phenotyping, we identified a single QTL for Psa resistance on Linkage Group (LG) 27 of 'Hort16A' revealing 16-19% phenotypic variance and candidate alleles for susceptibility and resistance at this loci. In addition, six minor QTLs were identified in P1 on distinct LGs, exerting 4-9% variance. Resistance in the F1 population is improved by additive effects from 'Hort16A' and P1 QTLs providing evidence that divergent genetic pathways interact to combat the virulent Psa strain. Two different bioassays further identified new QTLs for tissue-specific responses to Psa. The genetic marker at LG27 QTL was further verified for association with Psa resistance in diploid Actinidia chinensis populations. Transcriptome analysis of Psa-resistant and susceptible genotypes in field revealed hallmarks of basal defense and provided candidate RNA-biomarkers for screening for Psa resistance in greenhouse conditions.
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Affiliation(s)
- Jibran Tahir
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Stephen Hoyte
- The New Zealand Institute for Plant Food Research Limited, Hamilton, New Zealand
| | - Heather Bassett
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Cyril Brendolise
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92–169, Auckland, 1025 New Zealand
| | - Abhishek Chatterjee
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92–169, Auckland, 1025 New Zealand
| | - Kerry Templeton
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92–169, Auckland, 1025 New Zealand
| | - Cecilia Deng
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92–169, Auckland, 1025 New Zealand
| | - Ross Crowhurst
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92–169, Auckland, 1025 New Zealand
| | | | - Ed Morgan
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Andrew Wotton
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Keith Funnell
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Claudia Wiedow
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Mareike Knaebel
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Duncan Hedderley
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Joel Vanneste
- The New Zealand Institute for Plant Food Research Limited, Hamilton, New Zealand
| | - John McCallum
- The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand
| | - Kirsten Hoeata
- The New Zealand Institute for Plant and Food Research Limited, 412 No 1 Road, RD2, Te Puke, 3182 New Zealand
| | - Amardeep Nath
- The New Zealand Institute for Plant and Food Research Limited, 412 No 1 Road, RD2, Te Puke, 3182 New Zealand
| | - David Chagné
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
| | - Luis Gea
- The New Zealand Institute for Plant and Food Research Limited, 412 No 1 Road, RD2, Te Puke, 3182 New Zealand
| | - Susan E. Gardiner
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11030, Manawatu Mail Centre, Palmerston North, 4442 New Zealand
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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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Nikolić I, Berić T, Dimkić I, Popović T, Lozo J, Fira D, Stanković S. Biological control of Pseudomonas syringae pv. aptata on sugar beet with Bacillus pumilus SS-10.7 and Bacillus amyloliquefaciens (SS-12.6 and SS-38.4) strains. J Appl Microbiol 2018; 126:165-176. [PMID: 30117660 DOI: 10.1111/jam.14070] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 08/06/2018] [Accepted: 08/13/2018] [Indexed: 12/20/2022]
Abstract
AIM Assessment of biological control of Pseudomonas syringae pv. aptata using crude lipopeptide extracts (CLEs) of two Bacillus amyloliquefaciens strains (SS-12.6 and SS-38.4) and one Bacillus pumilus strain (SS-10.7). METHODS AND RESULTS The minimum inhibitory concentration (MIC) of CLEs and their combinations against the pathogen and potential interaction between the extracts were determined in vitro. The most effective antibacterial activity was achieved with the CLE from B. amyloliquefaciens SS-12.6, with an MIC value of 0·63 mg ml-1 . Interactions between CLE combinations were mostly indifferent. The biocontrol potential of CLEs, mixtures of CLEs, and cell culture of B. amyloliquefaciens SS-12.6 was tested on sugar beet plants inoculated with P. syringae pv. aptata P53. The best result in inhibiting the appearance of tissue necrosis (up to 92%) was achieved with B. amyloliquefaciens SS-12.6 cell culture. CONCLUSION This work demonstrated significant biocontrol potential of the CLE and cell culture of B. amyloliquefaciens SS-12.6 which successfully suppress leaf spot disease severity on sugar beet plants. SIGNIFICANCE AND IMPACT OF THE STUDY The findings of biocontrol of sugar beet emerging pathogen will contribute to growers in terms of alternative disease control management. This study represents first assessment of biological control of P. syringae pv. aptata.
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Affiliation(s)
- I Nikolić
- Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - T Berić
- Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - I Dimkić
- Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - T Popović
- Institute for Plant Protection and Environment, Belgrade, Serbia
| | - J Lozo
- Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - D Fira
- Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - S Stanković
- Faculty of Biology, University of Belgrade, Belgrade, Serbia
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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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57
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Hulin MT, Armitage AD, Vicente JG, Holub EB, Baxter L, Bates HJ, Mansfield JW, Jackson RW, Harrison RJ. Comparative genomics of Pseudomonas syringae reveals convergent gene gain and loss associated with specialization onto cherry (Prunus avium). THE NEW PHYTOLOGIST 2018; 219:672-696. [PMID: 29726587 DOI: 10.1111/nph.15182] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/22/2018] [Indexed: 05/12/2023]
Abstract
Genome-wide analyses of the effector- and toxin-encoding genes were used to examine the phylogenetics and evolution of pathogenicity amongst diverse strains of Pseudomonas syringae causing bacterial canker of cherry (Prunus avium), including pathovars P. syringae pv morsprunorum (Psm) races 1 and 2, P. syringae pv syringae (Pss) and P. syringae pv avii. Phylogenetic analyses revealed Psm races and P. syringae pv avii clades were distinct and were each monophyletic, whereas cherry-pathogenic strains of Pss were interspersed amongst strains from other host species. A maximum likelihood approach was used to predict effectors associated with pathogenicity on cherry. Pss possesses a smaller repertoire of type III effectors but has more toxin biosynthesis clusters than Psm and P. syringae pv avii. Evolution of cherry pathogenicity was correlated with gain of genes such as hopAR1 and hopBB1 through putative phage transfer and horizontal transfer respectively. By contrast, loss of the avrPto/hopAB redundant effector group was observed in cherry-pathogenic clades. Ectopic expression of hopAB and hopC1 triggered the hypersensitive reaction in cherry leaves, confirming computational predictions. Cherry canker provides a fascinating example of convergent evolution of pathogenicity that is explained by the mix of effector and toxin repertoires acting on a common host.
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Affiliation(s)
- Michelle T Hulin
- NIAB EMR, New Road, East Malling, ME19 6BJ, UK
- School of Biological Sciences, University of Reading, Reading, RG6 6AJ, UK
| | | | - Joana G Vicente
- School of Life Sciences, Warwick Crop Centre, University of Warwick, Wellesbourne, CV35 9EF, UK
| | - Eric B Holub
- School of Life Sciences, Warwick Crop Centre, University of Warwick, Wellesbourne, CV35 9EF, UK
| | - Laura Baxter
- School of Life Sciences, Warwick Crop Centre, University of Warwick, Wellesbourne, CV35 9EF, UK
| | | | - John W Mansfield
- Faculty of Natural Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Robert W Jackson
- School of Biological Sciences, University of Reading, Reading, RG6 6AJ, UK
| | - Richard J Harrison
- NIAB EMR, New Road, East Malling, ME19 6BJ, UK
- School of Biological Sciences, University of Reading, Reading, RG6 6AJ, UK
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Zeng Q, Cui Z, Wang J, Childs KL, Sundin GW, Cooley DR, Yang C, Garofalo E, Eaton A, Huntley RB, Yuan X, Schultes NP. Comparative genomics of Spiraeoideae-infecting Erwinia amylovora strains provides novel insight to genetic diversity and identifies the genetic basis of a low-virulence strain. MOLECULAR PLANT PATHOLOGY 2018; 19:1652-1666. [PMID: 29178620 PMCID: PMC6638132 DOI: 10.1111/mpp.12647] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 11/21/2017] [Accepted: 11/22/2017] [Indexed: 05/24/2023]
Abstract
Erwinia amylovora is the causal agent of fire blight, one of the most devastating diseases of apple and pear. Erwinia amylovora is thought to have originated in North America and has now spread to at least 50 countries worldwide. An understanding of the diversity of the pathogen population and the transmission to different geographical regions is important for the future mitigation of this disease. In this research, we performed an expanded comparative genomic study of the Spiraeoideae-infecting (SI) E. amylovora population in North America and Europe. We discovered that, although still highly homogeneous, the genetic diversity of 30 E. amylovora genomes examined was about 30 times higher than previously determined. These isolates belong to four distinct clades, three of which display geographical clustering and one of which contains strains from various geographical locations ('Widely Prevalent' clade). Furthermore, we revealed that strains from the Widely Prevalent clade displayed a higher level of recombination with strains from a clade strictly from the eastern USA, which suggests that the Widely Prevalent clade probably originated from the eastern USA before it spread to other locations. Finally, we detected variations in virulence in the SI E. amylovora strains on immature pear, and identified the genetic basis of one of the low-virulence strains as being caused by a single nucleotide polymorphism in hfq, a gene encoding an important virulence regulator. Our results provide insights into the population structure, distribution and evolution of SI E. amylovora in North America and Europe.
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Affiliation(s)
- Quan Zeng
- Department of Plant Pathology and EcologyThe Connecticut Agricultural Experiment StationNew Haven 06511CTUSA
| | - Zhouqi Cui
- Department of Plant Pathology and EcologyThe Connecticut Agricultural Experiment StationNew Haven 06511CTUSA
- Department of Biological SciencesUniversity of Wisconsin‐MilwaukeeMilwaukee 53211WIUSA
| | - Jie Wang
- Department of Plant BiologyMichigan State UniversityEast Lansing 48824MIUSA
| | - Kevin L. Childs
- Department of Plant BiologyMichigan State UniversityEast Lansing 48824MIUSA
| | - George W. Sundin
- Department of Plant, Soil, and Microbial SciencesMichigan State UniversityEast Lansing 48824MIUSA
| | - Daniel R. Cooley
- Stockbridge School of AgricultureUniversity of MassachusettsAmherst 01003MAUSA
| | - Ching‐Hong Yang
- Department of Biological SciencesUniversity of Wisconsin‐MilwaukeeMilwaukee 53211WIUSA
| | - Elizabeth Garofalo
- Stockbridge School of AgricultureUniversity of MassachusettsAmherst 01003MAUSA
| | - Alan Eaton
- Department of Agriculture, Nutrition, and Food SystemsUniversity of New HampshireDurham 03824NHUSA
| | - Regan B. Huntley
- Department of Plant Pathology and EcologyThe Connecticut Agricultural Experiment StationNew Haven 06511CTUSA
| | - Xiaochen Yuan
- Department of Biological SciencesUniversity of Wisconsin‐MilwaukeeMilwaukee 53211WIUSA
| | - Neil P. Schultes
- Department of Plant Pathology and EcologyThe Connecticut Agricultural Experiment StationNew Haven 06511CTUSA
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Wei H, Collmer A. Defining essential processes in plant pathogenesis with Pseudomonas syringae pv. tomato DC3000 disarmed polymutants and a subset of key type III effectors. MOLECULAR PLANT PATHOLOGY 2018; 19:1779-1794. [PMID: 29277959 PMCID: PMC6638048 DOI: 10.1111/mpp.12655] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/10/2017] [Accepted: 12/20/2017] [Indexed: 05/22/2023]
Abstract
Pseudomonas syringae pv. tomato DC3000 and its derivatives cause disease in tomato, Arabidopsis and Nicotiana benthamiana. The primary virulence factors include a repertoire of 29 effector proteins injected into plant cells by the type III secretion system and the phytotoxin coronatine. The complete repertoire of effector genes and key coronatine biosynthesis genes have been progressively deleted and minimally reassembled to reconstitute basic pathogenic ability in N. benthamiana, and in Arabidopsis plants that have mutations in target genes that mimic effector actions. This approach and molecular studies of effector activities and plant immune system targets have highlighted a small subset of effectors that contribute to essential processes in pathogenesis. Most notably, HopM1 and AvrE1 redundantly promote an aqueous apoplastic environment, and AvrPtoB and AvrPto redundantly block early immune responses, two conditions that are sufficient for substantial bacterial growth in planta. In addition, disarmed DC3000 polymutants have been used to identify the individual effectors responsible for specific activities of the complete repertoire and to more effectively study effector domains, effector interplay and effector actions on host targets. Such work has revealed that AvrPtoB suppresses cell death elicitation in N. benthamiana that is triggered by another effector in the DC3000 repertoire, highlighting an important aspect of effector interplay in native repertoires. Disarmed DC3000 polymutants support the natural delivery of test effectors and infection readouts that more accurately reveal effector functions in key pathogenesis processes, and enable the identification of effectors with similar activities from a broad range of other pathogens that also defeat plants with cytoplasmic effectors.
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Affiliation(s)
- Hai‐Lei Wei
- School of Integrative Plant ScienceSection of Plant Pathology and Plant–Microbe Biology, Cornell UniversityIthacaNY14853USA
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of AgricultureInstitute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural SciencesBeijing100081China
| | - Alan Collmer
- School of Integrative Plant ScienceSection of Plant Pathology and Plant–Microbe Biology, Cornell UniversityIthacaNY14853USA
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Baltrus DA, Orth KN. Understanding genomic diversity in Pseudomonas syringae throughout the forest and on the trees. THE NEW PHYTOLOGIST 2018; 219:482-484. [PMID: 29927494 DOI: 10.1111/nph.15269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Affiliation(s)
- David A Baltrus
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | - Kelly N Orth
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
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Abstract
Pseudomonas syringae is one of the best-studied plant pathogens and serves as a model for understanding host-microorganism interactions, bacterial virulence mechanisms and host adaptation of pathogens as well as microbial evolution, ecology and epidemiology. Comparative genomic studies have identified key genomic features that contribute to P. syringae virulence. P. syringae has evolved two main virulence strategies: suppression of host immunity and creation of an aqueous apoplast to form its niche in the phyllosphere. In addition, external environmental conditions such as humidity profoundly influence infection. P. syringae may serve as an excellent model to understand virulence and also of how pathogenic microorganisms integrate environmental conditions and plant microbiota to become ecologically robust and diverse pathogens of the plant kingdom.
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Smee MR, Baltrus DA, Hendry TA. Entomopathogenicity to Two Hemipteran Insects Is Common but Variable across Epiphytic Pseudomonas syringae Strains. FRONTIERS IN PLANT SCIENCE 2017; 8:2149. [PMID: 29312398 PMCID: PMC5742162 DOI: 10.3389/fpls.2017.02149] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/04/2017] [Indexed: 06/07/2023]
Abstract
Strains of the well-studied plant pathogen Pseudomonas syringae show large differences in their ability to colonize plants epiphytically and to inflict damage to hosts. Additionally, P. syringae can infect some sap-sucking insects and at least one P. syringae strain is highly virulent to insects, causing death to most individuals within as few as 4 days and growing to high population densities within insect hosts. The likelihood of agricultural pest insects coming into contact with transient populations of P. syringae while feeding on plants is high, yet the ecological implications of these interactions are currently not well understood as virulence has not been tested across a wide range of strains. To investigate virulence differences across strains we exposed the sweet potato whitefly, Bemisia tabaci, and the pea aphid, Acyrthosiphon pisum, both of which are cosmopolitan agricultural pests, to 12 P. syringae strains. We used oral inoculations with bacteria suspended in artificial diet in order to assay virulence while controlling for other variables such as differences in epiphytic growth ability. Generally, patterns of pathogenicity remain consistent across the two species of hemipteran insects, with bacterial strains from phylogroup II, or genomospecies 1, causing the highest rate of mortality with up to 86% of individuals dead after 72 h post infection. The rate of mortality is highly variable across strains, some significantly different from negative control treatments and others showing no discernable difference. Interestingly, one of the most pathogenic strains to both aphids and whiteflies (Cit7) is thought to be non-pathogenic on plants. We also found Cit7 to establish the highest epiphytic population after 48 h on fava beans. Between the nine P. syringae strains tested for epiphytic ability there is also much variation, but epiphytic ability was positively correlated with pathogenicity to insects, suggesting that the two traits may be linked and that strains likely to be found on plants may often be entomopathogenic. Our study highlights that there may be a use for epiphytic bacteria in the biological control of insect crop pests. It also suggests that interactions with epiphytic bacteria could be evolutionary and ecological drivers for hemipteran insects.
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Affiliation(s)
- Melanie R. Smee
- Department of Microbiology, Cornell University, Ithaca, NY, United States
| | - David A. Baltrus
- School of Plant Sciences, The University of Arizona, Tucson, AZ, United States
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, AZ, United States
| | - Tory A. Hendry
- Department of Microbiology, Cornell University, Ithaca, NY, United States
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Gomila M, Busquets A, Mulet M, García-Valdés E, Lalucat J. Clarification of Taxonomic Status within the Pseudomonas syringae Species Group Based on a Phylogenomic Analysis. Front Microbiol 2017; 8:2422. [PMID: 29270162 PMCID: PMC5725466 DOI: 10.3389/fmicb.2017.02422] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 11/22/2017] [Indexed: 11/13/2022] Open
Abstract
The Pseudomonas syringae phylogenetic group comprises 15 recognized bacterial species and more than 60 pathovars. The classification and identification of strains is relevant for practical reasons but also for understanding the epidemiology and ecology of this group of plant pathogenic bacteria. Genome-based taxonomic analyses have been introduced recently to clarify the taxonomy of the whole genus. A set of 139 draft and complete genome sequences of strains belonging to all species of the P. syringae group available in public databases were analyzed, together with the genomes of closely related species used as outgroups. Comparative genomics based on the genome sequences of the species type strains in the group allowed the delineation of phylogenomic species and demonstrated that a high proportion of strains included in the study are misclassified. Furthermore, representatives of at least 7 putative novel species were detected. It was also confirmed that P. ficuserectae, P. meliae, and P. savastanoi are later synonyms of P. amygdali and that “P. coronafaciens” should be revived as a nomenspecies.
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Affiliation(s)
- Margarita Gomila
- Microbiology, Department of Biology, Universitat de les Illes Balears, Palma de Mallorca, Spain
| | - Antonio Busquets
- Microbiology, Department of Biology, Universitat de les Illes Balears, Palma de Mallorca, Spain
| | - Magdalena Mulet
- Microbiology, Department of Biology, Universitat de les Illes Balears, Palma de Mallorca, Spain
| | - Elena García-Valdés
- Microbiology, Department of Biology, Universitat de les Illes Balears, Palma de Mallorca, Spain.,Institut Mediterrani d'Estudis Avançats (Consejo Superior de Investigaciones Científicas-Universidad de las Islas Baleares), Palma de Mallorca, Spain
| | - Jorge Lalucat
- Microbiology, Department of Biology, Universitat de les Illes Balears, Palma de Mallorca, Spain.,Institut Mediterrani d'Estudis Avançats (Consejo Superior de Investigaciones Científicas-Universidad de las Islas Baleares), Palma de Mallorca, Spain
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64
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Zeng Q, Wang J, Bertels F, Giordano PR, Chilvers MI, Huntley RB, Vargas JM, Sundin GW, Jacobs JL, Yang CH. Recombination of Virulence Genes in Divergent Acidovorax avenae Strains That Infect a Common Host. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:813-828. [PMID: 28682158 DOI: 10.1094/mpmi-06-17-0151-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Bacterial etiolation and decline (BED), caused by Acidovorax avenae, is an emerging disease of creeping bentgrass on golf courses in the United States. We performed the first comprehensive analysis of A. avenae on a nationwide collection of turfgrass- and maize-pathogenic A. avenae. Surprisingly, our results reveal that the turfgrass-pathogenic A. avenae in North America are not only highly divergent but also belong to two distinct phylogroups. Both phylogroups specifically infect turfgrass but are more closely related to maize pathogens than to each other. This suggests that, although the disease is only recently reported, it has likely been infecting turfgrass for a long time. To identify a genetic basis for the host specificity, we searched for genes closely related among turfgrass strains but distantly related to their homologs from maize strains. We found a cluster of 11 such genes generated by three ancient recombination events within the type III secretion system (T3SS) pathogenicity island. Ever since the recombination, the cluster has been conserved by strong purifying selection, hinting at its selective importance. Together our analyses suggest that BED is an ancient disease that may owe its host specificity to a highly conserved cluster of 11 T3SS genes.
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Affiliation(s)
- Quan Zeng
- 1 Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06504, U.S.A
| | - Jie Wang
- 2 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Frederic Bertels
- 3 Department for Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Plön 24306, Germany; and
| | - Paul R Giordano
- 2 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Martin I Chilvers
- 2 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Regan B Huntley
- 1 Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06504, U.S.A
| | - Joseph M Vargas
- 2 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - George W Sundin
- 2 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Janette L Jacobs
- 2 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Ching-Hong Yang
- 4 Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
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65
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Karasov TL, Barrett L, Hershberg R, Bergelson J. Similar levels of gene content variation observed for Pseudomonas syringae populations extracted from single and multiple host species. PLoS One 2017; 12:e0184195. [PMID: 28880925 PMCID: PMC5589212 DOI: 10.1371/journal.pone.0184195] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 08/18/2017] [Indexed: 12/22/2022] Open
Abstract
Bacterial strains of the same species collected from different hosts frequently exhibit differences in gene content. In the ubiquitous plant pathogen Pseudomonas syringae, more than 30% of genes encoded by each strain are not conserved among strains colonizing other host species. Although they are often implicated in host specificity, the role of this large fraction of the genome in host-specific adaptation is largely unexplored. Here, we sought to relate variation in gene content between strains infecting different species to variation that persists between strains on the same host. We fully sequenced a collection of P. syringae strains collected from wild Arabidopsis thaliana populations in the Midwestern United States. We then compared patterns of variation observed in gene content within these A. thaliana-isolated strains to previously published P. syringae sequence from strains collected on a diversity of crop species. We find that strains collected from the same host, A. thaliana, differ in gene content by 21%, 2/3 the level of gene content variation observed across strains collected from different hosts. Furthermore, the frequency with which specific genes are present among strains collected within the same host and among strains collected from different hosts is highly correlated. This implies that most gene content variation is maintained irrespective of host association. At the same time, we identify specific genes whose presence is important for P. syringae's ability to flourish within A. thaliana. Specifically, the A. thaliana strains uniquely share a genomic island encoding toxins active against plants and surrounding microbes, suggesting a role for microbe-microbe interactions in dictating the abundance within this host. Overall, our results demonstrate that while variation in the presence of specific genes can affect the success of a pathogen within its host, the majority of gene content variation is not strongly associated with patterns of host use.
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Affiliation(s)
- Talia L. Karasov
- Committee On Genetics Genomics & Systems Biology, University of Chicago, Chicago, Illinois, United States of America
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, United States of America
| | - Luke Barrett
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, United States of America
- CSIRO Agriculture, Canberra, ACT 2601, Australia
| | - Ruth Hershberg
- Department of Genetics, the Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Joy Bergelson
- Committee On Genetics Genomics & Systems Biology, University of Chicago, Chicago, Illinois, United States of America
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, United States of America
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66
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Vanneste JL. The Scientific, Economic, and Social Impacts of the New Zealand Outbreak of Bacterial Canker of Kiwifruit (Pseudomonas syringae pv. actinidiae). ANNUAL REVIEW OF PHYTOPATHOLOGY 2017; 55:377-399. [PMID: 28613977 DOI: 10.1146/annurev-phyto-080516-035530] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The introduction of Pseudomonas syringae pv. actinidiae (Psa) severely damaged the New Zealand kiwifruit industry, which in 2010 was based on only two cultivars. Despite an extraordinarily quick and strong response by industry, government, and scientists to minimize the economic and social impacts, the economic consequences of this outbreak were severe. Although our understanding of Psa epidemiology and control methods increased substantively over the past six years, the kiwifruit industry largely recovered because of the introduction of a less-susceptible yellow-fleshed cultivar. The New Zealand population of Psa is clonal but has evolved rapidly since its introduction by exchanging mobile genetic elements, including integrative conjugative elements (ICEs), with the local bacterial populations. In some cases, this has led to copper resistance. It is currently believed that the center of origin of the pathogen is Japan or Korea, but biovar 3, which is responsible for the global outbreak, originated in China.
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Affiliation(s)
- Joel L Vanneste
- The New Zealand Institute for Plant & Food Research Limited, Hamilton 3214, New Zealand;
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67
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Baltrus DA. Adaptation, specialization, and coevolution within phytobiomes. CURRENT OPINION IN PLANT BIOLOGY 2017; 38:109-116. [PMID: 28545003 DOI: 10.1016/j.pbi.2017.04.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 04/26/2017] [Indexed: 05/03/2023]
Abstract
Growth patterns of individual plants and evolutionary trajectories of plant communities are intimately linked with and are critically affected by host-associated microbiomes. Research across systems has begun to shed light on how these phytobiomes are established under laboratory and natural conditions, and have cultivated hope that a better understanding of the governing principles for host-microbe interactions can guide attempts to engineer microbiomes to boost agricultural yields. One important, yet relatively understudied, parameter in regards to phytobiome membership is the degree to which specialization and coevolution between plant species and microbes provides structure to these communities. In this article, I provide an overview of mechanisms enabling adaptation and specialization of phytobiome communities to host plants as well as the potential for plants themselves to recruit and cultivate beneficial interactions. I further explore the possibility of host-beneficial microbe coevolution and suggest particular situations that could promote the evolution of such close-knit partnerships. It is my hope that this overview will encourage future experiments that can begin to fill in this black box of ecological and evolutionary interactions across phytobiomes.
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Affiliation(s)
- David A Baltrus
- School of Plant Sciences, University of Arizona, Tucson, AZ 85721, United States; School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, AZ 85721, United States.
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68
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Caballo-Ponce E, Murillo J, Martínez-Gil M, Moreno-Pérez A, Pintado A, Ramos C. Knots Untie: Molecular Determinants Involved in Knot Formation Induced by Pseudomonas savastanoi in Woody Hosts. FRONTIERS IN PLANT SCIENCE 2017; 8:1089. [PMID: 28680437 PMCID: PMC5478681 DOI: 10.3389/fpls.2017.01089] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/06/2017] [Indexed: 05/10/2023]
Abstract
The study of the molecular basis of tree diseases is lately receiving a renewed attention, especially with the emerging perception that pathogens require specific pathogenicity and virulence factors to successfully colonize woody hosts. Pathosystems involving woody plants are notoriously difficult to study, although the use of model bacterial strains together with genetically homogeneous micropropagated plant material is providing a significant impetus to our understanding of the molecular determinants leading to disease. The gammaproteobacterium Pseudomonas savastanoi belongs to the intensively studied Pseudomonas syringae complex, and includes three pathogenic lineages causing tumorous overgrowths (knots) in diverse economically relevant trees and shrubs. As it occurs with many other bacteria, pathogenicity of P. savastanoi is dependent on a type III secretion system, which is accompanied by a core set of at least 20 effector genes shared among strains isolated from olive, oleander, and ash. The induction of knots of wild-type size requires that the pathogen maintains adequate levels of diverse metabolites, including the phytohormones indole-3-acetic acid and cytokinins, as well as cyclic-di-GMP, some of which can also regulate the expression of other pathogenicity and virulence genes and participate in bacterial competitiveness. In a remarkable example of social networking, quorum sensing molecules allow for the communication among P. savastanoi and other members of the knot microbiome, while at the same time are essential for tumor formation. Additionally, a distinguishing feature of bacteria from the P. syringae complex isolated from woody organs is the possession of a 15 kb genomic island (WHOP) carrying four operons and three other genes involved in degradation of phenolic compounds. Two of these operons mediate the catabolism of anthranilate and catechol and, together with another operon, are required for the induction of full-size tumors in woody hosts, but not in non-woody micropropagated plants. The use of transposon mutagenesis also uncovered a treasure trove of additional P. savastanoi genes affecting virulence and participating in diverse bacterial processes. Although there is still much to be learned on what makes a bacterium a successful pathogen of trees, we are already untying the knots.
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Affiliation(s)
- Eloy Caballo-Ponce
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Jesús Murillo
- Departamento de Producción Agraria, ETS de Ingenieros Agrónomos, Universidad Pública de NavarraPamplona, Spain
| | - Marta Martínez-Gil
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Alba Moreno-Pérez
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Adrián Pintado
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Cayo Ramos
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga–Consejo Superior de Investigaciones CientíficasMálaga, Spain
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69
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Venter SN, Palmer M, Beukes CW, Chan WY, Shin G, van Zyl E, Seale T, Coutinho TA, Steenkamp ET. Practically delineating bacterial species with genealogical concordance. Antonie van Leeuwenhoek 2017; 110:1311-1325. [DOI: 10.1007/s10482-017-0869-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 03/30/2017] [Indexed: 10/19/2022]
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70
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Castañeda-Ojeda MP, Moreno-Pérez A, Ramos C, López-Solanilla E. Suppression of Plant Immune Responses by the Pseudomonas savastanoi pv. savastanoi NCPPB 3335 Type III Effector Tyrosine Phosphatases HopAO1 and HopAO2. FRONTIERS IN PLANT SCIENCE 2017; 8:680. [PMID: 28529516 PMCID: PMC5418354 DOI: 10.3389/fpls.2017.00680] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/13/2017] [Indexed: 05/12/2023]
Abstract
The effector repertoire of the olive pathogen P. savastanoi pv. savastanoi NCPPB 3335 includes two members of the HopAO effector family, one of the most diverse T3E families of the P. syringae complex. The study described here explores the phylogeny of these dissimilar members, HopAO1 and HopAO2, among the complex and reveals their activities as immune defense suppressors. Although HopAO1 is predominantly encoded by phylogroup 3 strains isolated from woody organs of woody hosts, both HopAO1 and HopAO2 are phylogenetically clustered according to the woody/herbaceous nature of their host of isolation, suggesting host specialization of the HopAO family across the P. syringae complex. HopAO1 and HopAO2 translocate into plant cells and show hrpL-dependent expression, which allows their classification as actively deployed type III effectors. Our data also show that HopAO1 and HopAO2 possess phosphatase activity, a hallmark of the members of this family. Both of them exert an inhibitory effect on early plant defense responses, such as ROS production and callose deposition, and are able to suppress ETI responses induced by the effectorless polymutant of P. syringae pv. tomato DC3000 (DC3000D28E) in Nicotiana. Moreover, we demonstrate that a ΔhopAO1 mutant of P. savastanoi NCPBB 3335 exhibits a reduced fitness and virulence in olive plants, which supports the relevance of this effector during the interaction of this strain with its host plants. This work contributes to the field with the first report regarding functional analysis of HopAO homologs encoded by P. syringae or P. savastanoi strains isolated from woody hosts.
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Affiliation(s)
- María Pilar Castañeda-Ojeda
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga – Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Alba Moreno-Pérez
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga – Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Cayo Ramos
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga – Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Emilia López-Solanilla
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Parque Científico y Tecnológico de la UPMMadrid, Spain
- Departamento de Biotecnología y Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de MadridMadrid, Spain
- *Correspondence: Emilia López-Solanilla,
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