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Timilsina S, Kaur A, Sharma A, Ramamoorthy S, Vallad GE, Wang N, White FF, Potnis N, Goss EM, Jones JB. Xanthomonas as a Model System for Studying Pathogen Emergence and Evolution. PHYTOPATHOLOGY 2024; 114:1433-1446. [PMID: 38648116 DOI: 10.1094/phyto-03-24-0084-rvw] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
In this review, we highlight studies in which whole-genome sequencing, comparative genomics, and population genomics have provided unprecedented insights into past and ongoing pathogen evolution. These include new understandings of the adaptive evolution of secretion systems and their effectors. We focus on Xanthomonas pathosystems that have seen intensive study and improved our understanding of pathogen emergence and evolution, particularly in the context of host specialization: citrus canker, bacterial blight of rice, and bacterial spot of tomato and pepper. Across pathosystems, pathogens appear to follow a pattern of bursts of evolution and diversification that impact host adaptation. There remains a need for studies on the mechanisms of host range evolution and genetic exchange among closely related but differentially host-specialized species and to start moving beyond the study of specific strain and host cultivar pairwise interactions to thinking about these pathosystems in a community context.
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Affiliation(s)
- Sujan Timilsina
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Amandeep Kaur
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Anuj Sharma
- Department of Horticultural Sciences, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
| | | | - Gary E Vallad
- Department of Plant Pathology, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
| | - Nian Wang
- Department of Microbiology and Cell Science, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
| | - Frank F White
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
| | - Erica M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
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Tancos MA, Harney-Davila G, Cipollini D. Characterization of Emerging Xanthomonas campestris Isolates on the Nonnative Weed Garlic Mustard ( Alliaria petiolata). PLANT DISEASE 2024; 108:1418-1424. [PMID: 38199962 DOI: 10.1094/pdis-11-23-2391-sr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Nonnative plant infestations provide unique opportunities to investigate pathogen emergence with evolutionarily recent plant introduction events. The widespread distribution of invasive plants and their proximity to genetically related crops highlights the risks of nonnative plants acting as ancillary hosts and fostering microbial recombination and pathogen selection. Garlic mustard (Alliaria petiolata) is a widespread, nonnative cruciferous weed that grows throughout North America and along the forested edges of diverse agricultural fields. The recent identification of a novel Xanthomonas campestris pv. incanae strain isolated from a diseased A. petiolata population led to the current investigation of the distribution and diversity of X. campestris isolates from naturally infected A. petiolata. A total of 14 diseased A. petiolata sites were sampled across three states, leading to the identification of diverse X. campestris pathotypes and genotypes. Pathogenicity assays and multilocus sequence analyses identified pathogenic X. c. pv. incanae and X. c. pv. barbareae strains collected from disparate A. petiolata populations. Moreover, independently collected X. c. pv. incanae strains demonstrated a broad cruciferous host range by infecting cabbage (Brassica oleracea var. capitata), garden stock (Matthiola incana), and the cover crop yellow mustard (Guillenia flavescens). This study highlights the genetic variability and host potential of natural X. campestris populations and the potential risks to Brassica crops via widespread, dense garlic mustard reservoirs.
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Affiliation(s)
- Matthew A Tancos
- Foreign Disease-Weed Science Research Unit, United States Department of Agriculture-Agricultural Research Service, Frederick, MD 21702
| | | | - Don Cipollini
- Department of Biological Sciences, Wright State University, Dayton, OH 45435
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Chuang SC, Dobhal S, Alvarez AM, Arif M. Three new species, Xanthomonas hawaiiensis sp. nov., Stenotrophomonas aracearum sp. nov., and Stenotrophomonas oahuensis sp. nov., isolated from the Araceae family. Front Microbiol 2024; 15:1356025. [PMID: 38655077 PMCID: PMC11035887 DOI: 10.3389/fmicb.2024.1356025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
Xanthomonas and Stenotrophomonas are closely related genera in the family Lysobacteraceae. In our previous study of aroid-associated bacterial strains, most strains isolated from anthurium and other aroids were reclassified as X. phaseoli and other Xanthomonas species. However, two strains isolated from Spathiphyllum and Colocasia were phylogenetically distant from other strains in the Xanthomonas clade and two strains isolated from Anthurium clustered within the Stenotrophomonas clade. Phylogenetic trees based on 16S rRNA and nine housekeeping genes placed the former strains with the type strain of X. sacchari from sugarcane and the latter strains with the type strain of S. bentonitica from bentonite. In pairwise comparisons with type strains, the overall genomic relatedness indices required delineation of new species; digital DNA-DNA hybridization and average nucleotide identity values were lower than 70 and 95%, respectively. Hence, three new species are proposed: S. aracearum sp. nov. and S. oahuensis sp. nov. for two strains from anthurium and X. hawaiiensis sp. nov. for the strains from spathiphyllum and colocasia, respectively. The genome size of X. hawaiiensis sp. nov. is ~4.88 Mbp and higher than S. aracearum sp. nov. (4.33 Mbp) and S. oahuensis sp. nov. (4.68 Mbp). Gene content analysis revealed 425 and 576 core genes present in 40 xanthomonads and 25 stenotrophomonads, respectively. The average number of unique genes in Stenotrophomonas spp. was higher than in Xanthomonas spp., implying higher genetic diversity in Stenotrophomonas.
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Affiliation(s)
| | | | | | - Mohammad Arif
- Department of Plant and Environmental Protection Sciences, University of Hawaiʻi at Mānoa, Honolulu, HI, United States
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Pena MM, Bhandari R, Bowers RM, Weis K, Newberry E, Wagner N, Pupko T, Jones JB, Woyke T, Vinatzer BA, Jacques MA, Potnis N. Genetic and Functional Diversity Help Explain Pathogenic, Weakly Pathogenic, and Commensal Lifestyles in the Genus Xanthomonas. Genome Biol Evol 2024; 16:evae074. [PMID: 38648506 PMCID: PMC11032200 DOI: 10.1093/gbe/evae074] [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] [Accepted: 03/29/2024] [Indexed: 04/25/2024] Open
Abstract
The genus Xanthomonas has been primarily studied for pathogenic interactions with plants. However, besides host and tissue-specific pathogenic strains, this genus also comprises nonpathogenic strains isolated from a broad range of hosts, sometimes in association with pathogenic strains, and other environments, including rainwater. Based on their incapacity or limited capacity to cause symptoms on the host of isolation, nonpathogenic xanthomonads can be further characterized as commensal and weakly pathogenic. This study aimed to understand the diversity and evolution of nonpathogenic xanthomonads compared to their pathogenic counterparts based on their cooccurrence and phylogenetic relationship and to identify genomic traits that form the basis of a life history framework that groups xanthomonads by ecological strategies. We sequenced genomes of 83 strains spanning the genus phylogeny and identified eight novel species, indicating unexplored diversity. While some nonpathogenic species have experienced a recent loss of a type III secretion system, specifically the hrp2 cluster, we observed an apparent lack of association of the hrp2 cluster with lifestyles of diverse species. We performed association analysis on a large data set of 337 Xanthomonas strains to explain how xanthomonads may have established association with the plants across the continuum of lifestyles from commensals to weak pathogens to pathogens. Presence of distinct transcriptional regulators, distinct nutrient utilization and assimilation genes, transcriptional regulators, and chemotaxis genes may explain lifestyle-specific adaptations of xanthomonads.
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Affiliation(s)
- Michelle M Pena
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
- Present address: Department of Plant Pathology, University of Georgia, Tifton, GA, USA
| | - Rishi Bhandari
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Robert M Bowers
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kylie Weis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Eric Newberry
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Naama Wagner
- The Shmunis School of Biomedicine and Cancer Research, Tel-Aviv University, Tel Aviv, Israel
| | - Tal Pupko
- The Shmunis School of Biomedicine and Cancer Research, Tel-Aviv University, Tel Aviv, Israel
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Tanja Woyke
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Life and Environmental Sciences, University of California Merced, Merced, CA, USA
| | - Boris A Vinatzer
- School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Marie-Agnès Jacques
- Institut Agro, INRAE, IRHS, SFR QUASAV, University of Angers, Angers F-49000, France
| | - Neha Potnis
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
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Dubrow ZE, Carpenter SCD, Carter ME, Grinage A, Gris C, Lauber E, Butchachas J, Jacobs JM, Smart CD, Tancos MA, Noël LD, Bogdanove AJ. Cruciferous Weed Isolates of Xanthomonas campestris Yield Insight into Pathovar Genomic Relationships and Genetic Determinants of Host and Tissue Specificity. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:791-802. [PMID: 35536128 DOI: 10.1094/mpmi-01-22-0024-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pathovars of Xanthomonas campestris cause distinct diseases on different brassicaceous hosts. The genomic relationships among pathovars as well as the genetic determinants of host range and tissue specificity remain poorly understood despite decades of research. Here, leveraging advances in multiplexed long-read technology, we fully sequenced the genomes of a collection of X. campestris strains isolated from cruciferous crops and weeds in New York and California as well as strains from global collections, to investigate pathovar relationships and candidate genes for host- and tissue-specificity. Pathogenicity assays and genomic comparisons across this collection and publicly available X. campestris genomes revealed a correlation between pathovar and genomic relatedness and provide support for X. campestris pv. barbareae, the validity of which had been questioned. Linking strain host range with type III effector repertoires identified AvrAC (also 'XopAC') as a candidate host-range determinant, preventing infection of Matthiola incana, and this was confirmed experimentally. Furthermore, the presence of a copy of the cellobiosidase gene cbsA with coding sequence for a signal peptide was found to correlate with the ability to infect vascular tissues, in agreement with a previous study of diverse Xanthomonas species; however, heterologous expression in strains lacking the gene gave mixed results, indicating that factors in addition to cbsA influence tissue specificity of X. campestris pathovars. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Zoë E Dubrow
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Sara C D Carpenter
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Morgan E Carter
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
- School of Plant Sciences, University of Arizona, Tucson, AZ, U.S.A
| | - Ayress Grinage
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Carine Gris
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul Sabatier, Castanet-Tolosan, France
| | - Emmanuelle Lauber
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul Sabatier, Castanet-Tolosan, France
| | - Jules Butchachas
- Department of Plant Pathology, The Ohio State University, Columbus, OH, U.S.A
| | - Jonathan M Jacobs
- Department of Plant Pathology, The Ohio State University, Columbus, OH, U.S.A
| | - Christine D Smart
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
| | - Matthew A Tancos
- Foreign Disease-Weed Science Research Unit, United States Department of Agriculture-Agricultural Research Service, Frederick, MD, U.S.A
| | - Laurent D Noël
- LIPME, Université de Toulouse, INRAE, CNRS, Université Paul Sabatier, Castanet-Tolosan, France
| | - Adam J Bogdanove
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, U.S.A
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Ramnarine SDBJ, Jayaraman J, Ramsubhag A. Comparative genomics of the black rot pathogen Xanthomonas campestris pv. campestris and non-pathogenic co-inhabitant Xanthomonas melonis from Trinidad reveal unique pathogenicity determinants and secretion system profiles. PeerJ 2022; 9:e12632. [PMID: 35036136 PMCID: PMC8734464 DOI: 10.7717/peerj.12632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 11/22/2021] [Indexed: 11/20/2022] Open
Abstract
Black-rot disease caused by the phytopathogen Xanthomonas campestris pv. campestris (Xcc) continues to have considerable impacts on the productivity of cruciferous crops in Trinidad and Tobago and the wider Caribbean region. While the widespread occurrence of resistance of Xcc against bactericidal agrochemicals can contribute to the high disease burdens, the role of virulence and pathogenicity features of local strains on disease prevalence and severity has not been investigated yet. In the present study, a comparative genomic analysis was performed on 6 pathogenic Xcc and 4 co-isolated non-pathogenic Xanthomonas melonis (Xmel) strains from diseased crucifer plants grown in fields with heavy chemical use in Trinidad. Native isolates were grouped into two known and four newly assigned ribosomal sequence types (rST). Mobile genetic elements were identified which belonged to the IS3, IS5 family, Tn3 transposon, resolvases, and tra T4SS gene clusters. Additionally, exogenous plasmid derived sequences with origins from other bacterial species were characterised. Although several instances of genomic rearrangements were observed, native Xcc and Xmel isolates shared a significant level of structural homology with reference genomes, Xcc ATCC 33913 and Xmel CFBP4644, respectively. Complete T1SS hlyDB, T2SS, T4SS vir and T5SS xadA, yapH and estA gene clusters were identified in both species. Only Xmel strains contained a complete T6SS but no T3SS. Both species contained a complex repertoire of extracellular cell wall degrading enzymes. Native Xcc strains contained 37 T3SS and effector genes but a variable and unique profile of 8 avr, 4 xop and 1 hpa genes. Interestingly, Xmel strains contained several T3SS effectors with low similarity to references including avrXccA1 (~89%), hrpG (~73%), hrpX (~90%) and xopAZ (~87%). Furthermore, only Xmel genomes contained a CRISPR-Cas I-F array, but no lipopolysaccharide wxc gene cluster. Xmel strains were confirmed to be non-pathogenic by pathogenicity assays. The results of this study will be useful to guide future research into virulence mechanisms, agrochemical resistance, pathogenomics and the potential role of the co-isolated non-pathogenic Xanthomonas strains on Xcc infections.
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Affiliation(s)
- Stephen D B Jr Ramnarine
- Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Jayaraj Jayaraman
- Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Adesh Ramsubhag
- Department of Life Sciences, The University of the West Indies, St. Augustine, Trinidad and Tobago
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Te Molder D, Poncheewin W, Schaap PJ, Koehorst JJ. Machine learning approaches to predict the Plant-associated phenotype of Xanthomonas strains. BMC Genomics 2021; 22:848. [PMID: 34814827 PMCID: PMC8612006 DOI: 10.1186/s12864-021-08093-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/15/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The genus Xanthomonas has long been considered to consist predominantly of plant pathogens, but over the last decade there has been an increasing number of reports on non-pathogenic and endophytic members. As Xanthomonas species are prevalent pathogens on a wide variety of important crops around the world, there is a need to distinguish between these plant-associated phenotypes. To date a large number of Xanthomonas genomes have been sequenced, which enables the application of machine learning (ML) approaches on the genome content to predict this phenotype. Until now such approaches to the pathogenomics of Xanthomonas strains have been hampered by the fragmentation of information regarding pathogenicity of individual strains over many studies. Unification of this information into a single resource was therefore considered to be an essential step. RESULTS Mining of 39 papers considering both plant-associated phenotypes, allowed for a phenotypic classification of 578 Xanthomonas strains. For 65 plant-pathogenic and 53 non-pathogenic strains the corresponding genomes were available and de novo annotated for the presence of Pfam protein domains used as features to train and compare three ML classification algorithms; CART, Lasso and Random Forest. CONCLUSION The literature resource in combination with recursive feature extraction used in the ML classification algorithms provided further insights into the virulence enabling factors, but also highlighted domains linked to traits not present in pathogenic strains.
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Affiliation(s)
- Dennie Te Molder
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands
| | - Wasin Poncheewin
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands
| | - Peter J Schaap
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands
- UNLOCK, Wageningen University, Wageningen, the Netherlands
| | - Jasper J Koehorst
- Laboratory of Systems and Synthetic Biology, Wageningen University, Wageningen, the Netherlands.
- UNLOCK, Wageningen University, Wageningen, the Netherlands.
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Bakhshi Ganje M, Mackay J, Nicolaisen M, Shams-Bakhsh M. Comparative Genomics, Pangenome, and Phylogenomic Analyses of Brenneria spp., and Delineation of Brenneria izadpanahii sp. nov. PHYTOPATHOLOGY 2021; 111:78-95. [PMID: 32407252 DOI: 10.1094/phyto-04-20-0129-fi] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Brenneria species are bacterial plant pathogens mainly affecting woody plants. Association of all members with devastating disorders (e.g., acute oak decline in Iran and United Kingdom) are due to adaptation and pathogenic behavior in response to host and environmental factors. Some species, including B. goodwinii, B. salicis, and B. nigrifluens, also show endophytic residence. Here we show that all species including novel Brenneria sp. are closely related. Gene-based and genome/pangenome-based phylogeny divide the genus into two distinct lineages, Brenneria clades A and B. The two clades were functionally distinct and were consistent with their common and special potential activities as determined via annotation of functional domains. Pangenome analysis demonstrated that the core pathogenicity factors were highly conserved, an hrp gene cluster encoding a type III secretion system was found in all species except B. corticis. An extensive repertoire of candidate virulence factors was identified. Comparative genomics indicated a repertoire of plant cell wall degrading enzymes, metabolites/antibiotics, and numerous prophages providing new insights into Brenneria-host interactions and appropriate targets for further characterization. This work not only documented the genetic differentiation of Brenneria species but also delineates a more functionally driven understanding of Brenneria by comparison with relevant Pectobacteriaceae thereby substantially enriching the extent of information available for functional genomic investigations.
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Affiliation(s)
- Meysam Bakhshi Ganje
- Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran
| | - John Mackay
- Department of Plant Sciences, University of Oxford, Oxford, U.K
| | - Mogens Nicolaisen
- Faculty of Science and Technology, Department of Agroecology, Aarhus University, Forsøgsvej 1, 4200, Slagelse, Denmark
| | - Masoud Shams-Bakhsh
- Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran
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Kyrova EI, Dzhalilov FS, Ignatov AN. The role of epiphytic populations in pathogenesis of the genus Xanthomonas bacteria. BIO WEB OF CONFERENCES 2020. [DOI: 10.1051/bioconf/20202303010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Global climate warming and involvement of new regions with endemic populations of microorganisms in commercial seed production have led to an increase in the diversity of phytopathogenic bacteria that are affecting major crops, including the fruit trees. As a rule, emergence of new pathogens is associated with importation of infected seeds and planting material, cultivation of new species and varieties of plants, and expansion of agricultural trade with foreign countries. One of the leaders in diversity among phytopathogens is the genus Xanthomonas bacteria, affecting more than 400 plant species. Among the characteristic signs of xanthomonads is the high frequency of horizontal gene transfer both within the genus and between phylogenetically removed bacterial taxa – up to 25% of the genes are of this origin. In this paper, we consider another source of increasing the number of phytopathogenic species – by the epiphytic populations. These bacteria are the likely ancestral form of the phytopathogenic bacteria of the genus Xanthomonas.
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