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Oh EJ, Hwang IS, Kwon CT, Oh CS. A Putative Apoplastic Effector of Clavibacter capsici, ChpG Cc as Hypersensitive Response and Virulence (Hrv) Protein in Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:370-379. [PMID: 38148291 DOI: 10.1094/mpmi-09-23-0145-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: 12/28/2023]
Abstract
Clavibacter bacteria use secreted apoplastic effectors, such as putative serine proteases, for virulence in host plants and for hypersensitive response (HR) induction in nonhost plants. Previously, we have shown that Clavibacter capsici ChpGCc is important for the necrosis development in pepper (Capsicum annuum) leaves. Here, we determine the function of ChpGCc, along with three paralogous proteins, for HR induction in the apoplastic space of a nonhost plant, Nicotiana tabacum. The full-length and signal peptide-deleted (ΔSP) mature forms of all proteins fused with the tobacco PR1b signal sequence were generated. The full-length and ΔSP forms of ChpGCc and only the ΔSP forms of ChpECc and Pat-1Cc, but none of the ChpCCc, triggered HR. Based on the predicted protein structures, ChpGCc carries amino acids for a catalytic triad and a disulfide bridge in positions like Pat-1Cm. Substituting these amino acids of ChpGCc with alanine abolished or reduced HR-inducing activity. To determine whether these residues are important for necrosis development in pepper, alanine-substituted chpGCc genes were transformed into the C. capsici PF008ΔpCM1 strain, which lacks the intact chpGCc gene. The strain with any variants failed to restore the necrosis-causing ability. These results suggest that ChpGCc has a dual function as a virulence factor in host plants and an HR elicitor in nonhost plants. Based on our findings and previous results, we propose Clavibacter apoplastic effectors, such as ChpGCc, Pat-1Cm, Chp-7Cs, and ChpGCm, as hypersensitive response and virulence (Hrv) proteins that display phenotypic similarities to the hypersensitive response and pathogenicity (Hrp) proteins found in gram-negative bacteria. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Eom-Ji Oh
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Korea
| | - In Sun Hwang
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
| | - Choon-Tak Kwon
- Graduate School of Green-Bio Science, Kyung Hee University, Yongin 17104, Korea
| | - Chang-Sik Oh
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826, Korea
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Osdaghi E, Robertson AE, Jackson-Ziems TA, Abachi H, Li X, Harveson RM. Clavibacter nebraskensis causing Goss's wilt of maize: Five decades of detaining the enemy in the New World. MOLECULAR PLANT PATHOLOGY 2023; 24:675-692. [PMID: 36116105 DOI: 10.1111/mpp.13268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 06/11/2023]
Abstract
Goss's bacterial wilt and leaf blight of maize (Zea mays) caused by the gram-positive coryneform bacterium Clavibacter nebraskensis is an economically important disease in North America. C. nebraskensis is included within the high-risk list of quarantine pathogens by several plant protection organizations (EPPO code: CORBMI), hence it is under strict quarantine control around the world. The causal agent was reported for the first time on maize in Nebraska (USA) in 1969. After an outbreak during the 1970s, prevalence of the disease decreased in the 1980s to the early 2000s, before the disease resurged causing a serious threat to maize production in North America. The re-emergence of Goss's wilt in the corn belt of the United States led to several novel achievements in understanding the pathogen biology and disease control. In this review, we provide an updated overview of the pathogen taxonomy, biology, and epidemiology as well as management strategies of Goss's wilt disease. First, a taxonomic history of the pathogen is provided followed by symptomology and host range, genetic diversity, and pathogenicity mechanisms of the bacterium. Then, utility of high-throughput molecular approaches in the precise detection and identification of the pathogen and the management strategies of the disease are explained. Finally, we highlight the role of integrated pest management strategies to combat the risk of Goss's wilt in the 21st century maize industry. DISEASE SYMPTOMS Large (2-15 cm) tan to grey elongated oval lesions with wavy, irregular water-soaked margins on the leaves. The lesions often start at the leaf tip or are associated with wounding caused by hail or wind damage. Small (1 mm in diameter), dark, discontinuous water-soaked spots, known as "freckles", can be observed in the periphery of lesions. When backlit, the freckles appear translucent. Early infection (prior to growth stage V6) may become systemic and cause seedlings to wilt, wither, and die. Coalescence of lesions results in leaf blighting. HOST RANGE Maize (Zea mays) is the only economic host of the pathogen. A number of Poaceae species are reported to act as secondary hosts for C. nebraskensis. TAXONOMIC STATUS OF THE PATHOGEN Class: Actinobacteria; Order: Micrococcales; Family: Microbacteriaceae; Genus: Clavibacter; Species: Clavibacter nebraskensis. SYNONYMS Corynebacterium nebraskense (Schuster, 1970) Vidaver & Mandel 1974; Corynebacterium michiganense pv. nebraskense (Vidaver & Mandel 1974) Dye & Kemp 1977; Corynebacterium michiganense subsp. nebraskense (Vidaver & Mandel 1974) Carlson & Vidaver 1982; Clavibacter michiganense subsp. nebraskense (Vidaver & Mandel 1974) Davis et al. 1984; Clavibacter michiganensis subsp. nebraskensis (Vidaver & Mandel 1974) Davis et al. 1984. TYPE MATERIALS ATCC 27794T ; CFBP 2405T ; ICMP 3298T ; LMG 3700T ; NCPPB 2581T . MICROBIOLOGICAL PROPERTIES Cells are gram-positive, orange-pigmented, pleomorphic club- or rod-shaped, nonspore-forming, nonmotile, and without flagella, approximately 0.5 × 1-2.0 μm. DISTRIBUTION The pathogen is restricted to Canada and the United States. PHYTOSANITARY CATEGORIZATION EPPO code CORBNE.
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Affiliation(s)
- Ebrahim Osdaghi
- Department of Plant Protection, College of Agriculture, University of Tehran, Karaj, Iran
| | - Alison E Robertson
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, Iowa, USA
| | - Tamra A Jackson-Ziems
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Hamid Abachi
- Department of Plant Protection, College of Agriculture, University of Tehran, Karaj, Iran
| | - Xiang Li
- Canadian Food Inspection Agency, Charlottetown Laboratory, Charlottetown, Prince Edward Island, Canada
| | - Robert M Harveson
- Panhandle Research & Extension Center, University of Nebraska, Scottsbluff, Nebraska, USA
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Park IW, Hwang IS, Oh EJ, Kwon CT, Oh CS. Nicotiana benthamiana, a Surrogate Host to Study Novel Virulence Mechanisms of Gram-Positive Bacteria, Clavibacter michiganensis, and C. capsici in Plants. FRONTIERS IN PLANT SCIENCE 2022; 13:876971. [PMID: 35620684 PMCID: PMC9127732 DOI: 10.3389/fpls.2022.876971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/25/2022] [Indexed: 06/11/2023]
Abstract
Clavibacter michiganensis is a Gram-positive bacterium that causes bacterial canker and wilting in host plants like tomato. Two major virulence genes encoding a cellulase (celA) and a putative serine protease (pat-1) have been reported. Here we show that Nicotiana benthamiana, a commonly used model plant for studying molecular plant-pathogen interactions, is a surrogate host of C. michiganensis and C. capsici. When a low concentration of two Clavibacter species, C. michiganensis and C. capsici, were infiltrated into N. benthamiana leaves, they caused blister-like lesions closely associated with cell death and the generation of reactive oxygen species and proliferated significantly like a pathogenic bacterium. By contrast, they did not cause any disease symptoms in N. tabacum leaves. The celA and pat-1 mutants of C. michiganensis still caused blister-like lesions and cankers like the wild-type strain. When a high concentration of two Clavibacter species and two mutant strains were infiltrated into N. benthamiana leaves, all of them caused strong and rapid necrosis. However, only C. michiganensis strains, including the celA and pat-1 mutants, caused wilting symptoms when it was injected into stems. When two Clavibacter species and two mutants were infiltrated into N. tabacum leaves at the high concentration, they (except for the pat-1 mutant) caused a strong hypersensitive response. These results indicate that C. michiganensis causes blister-like lesions, canker, and wilting in N. benthamiana, and celA and pat-1 genes are not necessary for the development of these symptoms. Overall, N. benthamiana is a surrogate host of Clavibacter species, and their novel virulence factors are responsible for disease development in this plant.
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Affiliation(s)
- In Woong Park
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin, South Korea
| | - In Sun Hwang
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin, South Korea
| | - Eom-Ji Oh
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin, South Korea
| | - Choon-Tak Kwon
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin, South Korea
| | - Chang-Sik Oh
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin, South Korea
- Graduate School of Green-Bio Science, Kyung Hee University, Yongin, South Korea
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Hwang IS, Oh EJ, Song E, Park IW, Lee Y, Sohn KH, Choi D, Oh CS. An Apoplastic Effector Pat-1 Cm of the Gram-Positive Bacterium Clavibacter michiganensis Acts as Both a Pathogenicity Factor and an Immunity Elicitor in Plants. FRONTIERS IN PLANT SCIENCE 2022; 13:888290. [PMID: 35432427 PMCID: PMC9006514 DOI: 10.3389/fpls.2022.888290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 03/14/2022] [Indexed: 05/09/2023]
Abstract
Clavibacter michiganensis, a Gram-positive plant-pathogenic bacterium, utilizes apoplastic effectors for disease development in host plants. Here, we determine the roles of Pat-1Cm (a putative serine protease) in pathogenicity and plant immunity. Pat-1Cm was found to be a genuine secreted protein, and the secreted mature form did not carry the first 33 amino acids predicted to be a signal peptide (SP). The pat-1Cm mutant impaired to cause wilting, but still caused canker symptom in tomato. Moreover, this mutant failed to trigger the hypersensitive response (HR) in a nonhost Nicotiana tabacum. Among orthologs and paralogs of pat-1Cm , only chp-7Cs from Clavibacter sepedonicus, a potato pathogen, successfully complemented pat-1Cm function in pathogenicity in tomato, whereas all failed to complement pat-1Cm function in HR induction in N. tabacum. Based on the structural prediction, Pat-1Cm carried a catalytic triad for putative serine protease, and alanine substitution of any amino acids in the triad abolished both pathogenicity and HR-inducing activities of Pat-1Cm in C. michiganensis. Ectopic expression of pat-1Cm with an SP from tobacco secreted protein triggered HR in N. tabacum, but not in tomato, whereas a catalytic triad mutant failed to induce HR. Inoculation of the pat-1Cm mutant mixed with the mutant of another apoplastic effector CelA (cellulase) caused severe wilting in tomato, indicating that these two apoplastic effectors can functionally cooperate in pathogenicity. Overall, these results indicate that Pat-1Cm is a distinct secreted protein carrying a functional catalytic triad for serine protease and this enzymatic activity might be critical for both pathogenicity and HR-eliciting activities of Pat-1Cm in plants.
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Affiliation(s)
- In Sun Hwang
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin, South Korea
| | - Eom-Ji Oh
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin, South Korea
| | - Eunbee Song
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin, South Korea
| | - In Woong Park
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin, South Korea
| | - Yoonyoung Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Kee Hoon Sohn
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, South Korea
| | - Doil Choi
- Department of Plant Science, Plant Immunity Research Center, Plant Genomics and Breeding Institute, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Chang-Sik Oh
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin, South Korea
- Graduate School of Biotechnology, Kyung Hee University, Yongin, South Korea
- *Correspondence: Chang-Sik Oh,
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Stevens DM, Tang A, Coaker G. A Genetic Toolkit for Investigating Clavibacter Species: Markerless Deletion, Permissive Site Identification, and an Integrative Plasmid. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:1336-1345. [PMID: 34890250 DOI: 10.1094/mpmi-07-21-0171-ta] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The development of knockout mutants and expression variants are critical for understanding genotype-phenotype relationships. However, advances in these techniques in gram-positive actinobacteria have stagnated over the last decade. Actinobacteria in the Clavibacter genus are composed of diverse crop pathogens that cause a variety of wilt and cankering diseases. Here, we present a suite of tools for genetic manipulation in the tomato pathogen Clavibacter michiganensis including a markerless deletion system, an integrative plasmid, and an R package for identification of permissive sites for plasmid integration. The vector pSelAct-KO is a recombination-based, markerless knockout system that uses dual selection to engineer seamless deletions of a region of interest, providing opportunities for repeated higher-order genetic knockouts. The efficacy of pSelAct-KO was demonstrated in C. michiganensis and was confirmed using whole-genome sequencing. We developed permissR, an R package to identify permissive sites for chromosomal integration, which can be used in conjunction with pSelAct-Express, a nonreplicating integrative plasmid that enables recombination into a permissive genomic location. Expression of enhanced green fluorescent protein by pSelAct-Express was verified in two candidate permissive regions predicted by permissR in C. michiganensis. These molecular tools are essential advances for investigating gram-positive actinobacteria, particularly for important pathogens in the Clavibacter genus.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Danielle M Stevens
- Integrative Genetics and Genomics Graduate Group, University of California, Davis, Davis, CA 95616, U.S.A
- Department of Plant Pathology, University of California, Davis, Davis, CA 95616, U.S.A
| | - Andrea Tang
- Department of Plant Pathology, University of California, Davis, Davis, CA 95616, U.S.A
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, Davis, CA 95616, U.S.A
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Christakis CA, Daskalogiannis G, Chatzaki A, Markakis EA, Mermigka G, Sagia A, Rizzo GF, Catara V, Lagkouvardos I, Studholme DJ, Sarris PF. Endophytic Bacterial Isolates From Halophytes Demonstrate Phytopathogen Biocontrol and Plant Growth Promotion Under High Salinity. Front Microbiol 2021; 12:681567. [PMID: 34017321 PMCID: PMC8129196 DOI: 10.3389/fmicb.2021.681567] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/07/2021] [Indexed: 01/22/2023] Open
Abstract
Halophytic endophytes potentially contribute to the host's adaptation to adverse environments, improving its tolerance against various biotic and abiotic stresses. Here, we identified the culturable endophytic bacteria of three crop wild relative (CWR) halophytes: Cakile maritima, Matthiola tricuspidata, and Crithmum maritimum. In the present study, the potential of these isolates to improve crop adaptations to various stresses was investigated, using both in vitro and in-planta approaches. Endophytic isolates were identified by their 16S rRNA gene sequence and evaluated for their ability to: grow in vitro in high levels of NaCl; inhibit the growth of the economically important phytopathogens Verticillium dahliae, Ralstonia solanacearum, and Clavibacter michiganensis and the human pathogen Aspergillus fumigatus; provide salt tolerance in-planta; and provide growth promoting effect in-planta. Genomes of selected isolates were sequenced. In total, 115 endophytic isolates were identified. At least 16 isolates demonstrated growth under increased salinity, plant growth promotion and phytopathogen antagonistic activity. Three showed in-planta suppression of Verticillium growth. Furthermore, representatives of three novel species were identified: two Pseudomonas species and one Arthrobacter. This study provides proof-of-concept that the endophytes from CWR halophytes can be used as "bio-inoculants," for the enhancement of growth and stress tolerance in crops, including the high-salinity stress.
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Affiliation(s)
- Christos A Christakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece
| | | | - Anastasia Chatzaki
- Laboratory of Mycology, Department of Viticulture, Vegetable Crops, Floriculture and Plant Protection, Institute of Olive Tree, Subtropical Crops and Viticulture, Hellenic Agricultural Organization DIMITRA, Heraklion, Greece
| | - Emmanouil A Markakis
- Laboratory of Mycology, Department of Viticulture, Vegetable Crops, Floriculture and Plant Protection, Institute of Olive Tree, Subtropical Crops and Viticulture, Hellenic Agricultural Organization DIMITRA, Heraklion, Greece
| | - Glykeria Mermigka
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece
| | - Angeliki Sagia
- Department of Biology, University of Crete, Heraklion, Greece
| | - Giulio Flavio Rizzo
- Department of Agriculture, Food and Environment, University of Catania, Catania, Italy
| | - Vittoria Catara
- Department of Agriculture, Food and Environment, University of Catania, Catania, Italy
| | - Ilias Lagkouvardos
- ZIEL-Institute for Food and Health, Technical University of Munich, Freising, Germany
| | | | - Panagiotis F Sarris
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas, Heraklion, Greece.,Department of Biology, University of Crete, Heraklion, Greece.,Biosciences, University of Exeter, Exeter, United Kingdom
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Rocha J, Shapiro LR, Kolter R. A horizontally acquired expansin gene increases virulence of the emerging plant pathogen Erwinia tracheiphila. Sci Rep 2020; 10:21743. [PMID: 33303810 PMCID: PMC7729394 DOI: 10.1038/s41598-020-78157-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 11/09/2020] [Indexed: 12/16/2022] Open
Abstract
Erwinia tracheiphila is a bacterial plant pathogen that causes a fatal wilt infection in some cucurbit crop plants. Wilt symptoms are thought to be caused by systemic bacterial colonization through xylem that impedes sap flow. However, the genetic determinants of within-plant movement are unknown for this pathogen species. Here, we find that E. tracheiphila has horizontally acquired an operon with a microbial expansin (exlx) gene adjacent to a glycoside hydrolase family 5 (gh5) gene. Plant inoculation experiments with deletion mutants in the individual genes (Δexlx and Δgh5) and the full operon (Δexlx-gh5) resulted in decreased severity of wilt symptoms, decreased mortality rate, and impaired systemic colonization compared to the Wt strain. Co-inoculation experiments with Wt and Δexlx-gh5 rescued the movement defect of the mutant strain, suggesting that expansin and GH5 function extracellularly. Together, these results show that expansin-GH5 contributes to systemic movement through xylem, leading to rapid wilt symptom development and higher rates of plant death. The presence of expansin genes in diverse species of bacterial and fungal wilt-inducing pathogens suggests that microbial expansin proteins may be an under-appreciated virulence factor for many pathogen species.
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Affiliation(s)
- Jorge Rocha
- Department of Microbiology, Harvard Medical School, Boston, MA, USA.
- Conacyt-Centro de Investigación y Desarrollo en Agrobiotecnología Alimentaria, San Agustin Tlaxiaca, 42163, Hidalgo, Mexico.
| | - Lori R Shapiro
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Roberto Kolter
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
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8
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Hwang IS, Oh EJ, Oh CS. Transcriptional Changes of Plant Defense-Related Genes in Response to Clavibacter Infection in Pepper and Tomato. THE PLANT PATHOLOGY JOURNAL 2020; 36:450-458. [PMID: 33082729 PMCID: PMC7542022 DOI: 10.5423/ppj.oa.07.2020.0124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 08/20/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
Pepper and tomato plants infected with two Clavibacter species, C. capsici and C. michiganensis have shown different patterns of disease development depending on their virulence. Here, we investigated how pepper and tomato plants respond to infection by the high-virulent or low-virulent Clavibacter strains. For this, we chose two strains of each Clavibacter species to show different virulence level in the host plants. Although low-virulent strains showed less disease symptoms, they grew almost the same level as the high-virulent strains in both plants. To further examine the response of host plants to Clavibacter infection, we analyzed the expression patterns of plant defense-related genes in the leaves inoculated with different strains of C. capsici and C. michiganensis. Pepper plants infected with high-virulent C. capsici strain highly induced the expression of CaPR1, CaDEF, CaPR4b, CaPR10, and CaLOX1 at 5 days after inoculation (dai), but their expression was much less in low-virulent Clavibacter infection. Expression of CaSAR8.2 was induced at 2 dai, regardless of virulence level. Expression of GluA, Pin2, and PR2 in tomato plants infected with high-virulent C. michiganensis were much higher at 5 dai, compared with mock or low-virulent strain. Expression of PR1a, Osmotin-like, Chitinase, and Chitinase class 2 was increased, regardless of virulence level. Expression of LoxA gene was not affected by Clavibacter inoculation. These results suggested that Clavibacter infection promotes induction of certain defense-related genes in host plants and that differential expression of those genes by low-virulent Clavibacter infection might be affected by their endophytic lifestyle in plants.
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Affiliation(s)
- In Sun Hwang
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin 704, Korea
| | - Eom-Ji Oh
- Graduate School of Biotechnology, Kyung Hee University, Yongin 17104, Korea
| | - Chang-Sik Oh
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin 704, Korea
- Graduate School of Biotechnology, Kyung Hee University, Yongin 17104, Korea
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9
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Hwang IS, Lee HM, Oh E, Lee S, Heu S, Oh C. Plasmid composition and the chpG gene determine the virulence level of Clavibacter capsici natural isolates in pepper. MOLECULAR PLANT PATHOLOGY 2020; 21:808-819. [PMID: 32196887 PMCID: PMC7214350 DOI: 10.1111/mpp.12932] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 02/21/2020] [Accepted: 02/22/2020] [Indexed: 05/23/2023]
Abstract
The gram-positive bacterial species Clavibacter capsici causes necrosis and canker in pepper plants. Genomic and functional analyses of C. capsici type strain PF008 have shown that multiple virulence genes exist in its two plasmids. We aimed to identify the key determinants that control the virulence of C. capsici. Pepper leaves inoculated with 54 natural isolates exhibited significant variation in the necrosis. Six isolates showed very low virulence, but their population titres in plants were not significantly different from those of the highly virulent isolates. All six isolates lacked the pCM1Cc plasmid that carries chpG, which has been shown to be required for virulence and encodes a putative serine protease, but two of them, isolates 1,106 and 1,207, had the intact chpG elsewhere in the genome. Genomic analysis of these two isolates revealed that chpG was located in the pCM2Cc plasmid, and two highly homologous regions were present next to the chpG locus. The chpG expression in isolate 1,106 was not induced in plants. Introduction of chpG of the PF008 strain into the six low-virulence isolates restored their virulence to that of PF008. Our findings indicate that there are at least three different variant groups of C. capsici and that the plasmid composition and the chpG gene are critical for determining the virulence level. Moreover, our findings also indicate that the virulence level of C. capsici does not directly correlate with bacterial titres in plants.
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Affiliation(s)
- In Sun Hwang
- Department of Horticultural BiotechnologyCollege of Life SciencesKyung Hee UniversityYonginSouth Korea
| | - Hyo Min Lee
- Department of Horticultural BiotechnologyCollege of Life SciencesKyung Hee UniversityYonginSouth Korea
| | - Eom‐Ji Oh
- Department of Horticultural BiotechnologyCollege of Life SciencesKyung Hee UniversityYonginSouth Korea
| | - Seungdon Lee
- Planning and Coordination DivisionNational Institute of Agricultural SciencesRural Development AdministrationWanjuSouth Korea
| | - Sunggi Heu
- Crop Cultivation and Environment Research DivisionNational Institute of Crop ScienceRural Development AdministrationSuwonSouth Korea
| | - Chang‐Sik Oh
- Department of Horticultural BiotechnologyCollege of Life SciencesKyung Hee UniversityYonginSouth Korea
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10
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Thapa SP, Davis EW, Lyu Q, Weisberg AJ, Stevens DM, Clarke CR, Coaker G, Chang JH. The Evolution, Ecology, and Mechanisms of Infection by Gram-Positive, Plant-Associated Bacteria. ANNUAL REVIEW OF PHYTOPATHOLOGY 2019; 57:341-365. [PMID: 31283433 DOI: 10.1146/annurev-phyto-082718-100124] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Gram-positive bacteria are prominent members of plant-associated microbial communities. Although many are hypothesized to be beneficial, some are causative agents of economically important diseases of crop plants. Because the features of Gram-positive bacteria are fundamentally different relative to those of Gram-negative bacteria, the evolution and ecology as well as the mechanisms used to colonize and infect plants also differ. Here, we discuss recent advances in our understanding of Gram-positive, plant-associated bacteria and provide a framework for future research directions on these important plant symbionts.
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Affiliation(s)
- Shree P Thapa
- Department of Plant Pathology, University of California, Davis, California 95616, USA
| | - Edward W Davis
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA;
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon 97331, USA
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331, USA
| | - Qingyang Lyu
- Department of Plant Pathology, University of California, Davis, California 95616, USA
| | - Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA;
| | - Danielle M Stevens
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA;
- Integrative Genetics and Genomics, University of California, Davis, California 95616, USA
| | - Christopher R Clarke
- Genetic Improvement for Fruits and Vegetables Laboratory, Agricultural Research Service, US Department of Agriculture, Beltsville, Maryland 20705, USA
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, California 95616, USA
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331, USA;
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon 97331, USA
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331, USA
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Hwang IS, Oh EJ, Lee HB, Oh CS. Functional Characterization of Two Cellulase Genes in the Gram-Positive Pathogenic Bacterium Clavibacter michiganensis for Wilting in Tomato. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:491-501. [PMID: 30345870 DOI: 10.1094/mpmi-08-18-0227-r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Diverse plant pathogens secrete cellulases to degrade plant cell walls. Previously, the plasmid-borne cellulase gene celA was shown to be important for the virulence of the gram-positive bacterium Clavibacter michiganensis in tomato. However, details of the contribution of cellulases to the development of wilting in tomato have not been well-determined. To better understand the contribution of cellulases to the virulence of C. michiganensis in tomato, a mutant lacking cellulase activity was generated and complemented with truncated forms of certain cellulase genes, and virulence of those strain was examined. A celA mutant of the C. michiganensis type strain LMG7333 lost its cellulase activity and almost all its ability to cause wilting in tomato. The cellulase catalytic domain and cellulose-binding domain of CelA together were sufficient for both cellulase activity and the development of wilting in tomato. However, the expansin domain did not affect virulence or cellulase activity. The celA ortholog of Clavibacter sepedonicus restored the full virulence of the celA mutant of C. michiganensis. Another cellulase gene, celB, located in the chromosome, carries a single-base deletion in most C. michiganensis strains but does not carry a functional signal peptide in its N terminus. Nevertheless, an experimentally modified CelB protein with a CelA signal peptide was secreted and able to cause wilting in tomato. These results indicate that cellulases are major virulence factors of C. michiganensis that causes wilting in tomato. Furthermore, there are natural variations among cellulase genes directly affecting their function.
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Affiliation(s)
- In Sun Hwang
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin 17104, Korea
| | - Eom-Ji Oh
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin 17104, Korea
| | - Han Beoyl Lee
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin 17104, Korea
| | - Chang-Sik Oh
- Department of Horticultural Biotechnology, Kyung Hee University, Yongin 17104, Korea
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