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Verma RK, Roman-Reyna V, Raanan H, Coaker G, Jacobs JM, Teper D. Allelic variations in the chpG effector gene within Clavibacter michiganensis populations determine pathogen host range. PLoS Pathog 2024; 20:e1012380. [PMID: 39028765 PMCID: PMC11290698 DOI: 10.1371/journal.ppat.1012380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 07/31/2024] [Accepted: 06/27/2024] [Indexed: 07/21/2024] Open
Abstract
Plant pathogenic bacteria often have a narrow host range, which can vary among different isolates within a population. Here, we investigated the host range of the tomato pathogen Clavibacter michiganensis (Cm). We determined the genome sequences of 40 tomato Cm isolates and screened them for pathogenicity on tomato and eggplant. Our screen revealed that out of the tested isolates, five were unable to cause disease on any of the hosts, 33 were exclusively pathogenic on tomato, and two were capable of infecting both tomato and eggplant. Through comparative genomic analyses, we identified that the five non-pathogenic isolates lacked the chp/tomA pathogenicity island, which has previously been associated with virulence in tomato. In addition, we found that the two eggplant-pathogenic isolates encode a unique allelic variant of the putative serine hydrolase chpG (chpGC), an effector that is recognized in eggplant. Introduction of chpGC into a chpG inactivation mutant in the eggplant-non-pathogenic strain Cm101, failed to complement the mutant, which retained its ability to cause disease in eggplant and failed to elicit hypersensitive response (HR). Conversely, introduction of the chpG variant from Cm101 into an eggplant pathogenic Cm isolate (C48), eliminated its pathogenicity on eggplant, and enabled C48 to elicit HR. Our study demonstrates that allelic variation in the chpG effector gene is a key determinant of host range plasticity within Cm populations.
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Affiliation(s)
- Raj Kumar Verma
- Dept. of Plant Pathology and Weed Research, Agricultural Research Organization—Volcani Institute, Rishon LeZion, Israel
| | - Veronica Roman-Reyna
- Dept. Of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Hagai Raanan
- Dept. of Plant Pathology and Weed Research, Agricultural Research Organization—Gilat Research Center, Negev, Israel
| | - Gitta Coaker
- Dept. of Plant Pathology, University of California Davis, Davis, California, United States of America
| | - Jonathan M. Jacobs
- Dept. of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
- Infectious Diseases Institute, The Ohio State University, Columbus, Ohio, United States of America
| | - Doron Teper
- Dept. of Plant Pathology and Weed Research, Agricultural Research Organization—Volcani Institute, Rishon LeZion, Israel
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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: 3] [Impact Index Per Article: 3.0] [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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Verma RK, Teper D. Immune recognition of the secreted serine protease ChpG restricts the host range of Clavibacter michiganensis from eggplant varieties. MOLECULAR PLANT PATHOLOGY 2022; 23:933-946. [PMID: 35441490 PMCID: PMC9190982 DOI: 10.1111/mpp.13215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 05/06/2023]
Abstract
Bacterial wilt and canker caused by Clavibacter michiganensis (Cm) inflict considerable damage in tomato-growing regions around the world. Cm has a narrow host range and can cause disease in tomato but not in many eggplant varieties. The pathogenicity of Cm is dependent on secreted serine proteases, encoded by the chp/tomA pathogenicity island (PI), and the pCM2 plasmid. Screening combinations of PI deletion mutants and plasmid-cured strains found that Cm-mediated hypersensitive response (HR) in the Cm-resistant eggplant variety Black Queen is dependent on the chp/tomA PI. Singular reintroduction of PI-encoded serine proteases into Cm∆PI identified that the HR is elicited by the protease ChpG. Eggplant leaves infiltrated with a chpG marker exchange mutant (CmΩchpG) did not display an HR, and infiltration of purified ChpG protein elicited immune responses in eggplant but not in Cm-susceptible tomato. Virulence assays found that while wild-type Cm and the CmΩchpG complemented strain were nonpathogenic on eggplant, CmΩchpG caused wilt and canker symptoms. Additionally, bacterial populations in CmΩchpG-inoculated eggplant stem tissues were c.1000-fold higher than wild-type and CmΩchpG-complemented Cm strains. Pathogenicity tests conducted in multiple Cm-resistance eggplant varieties demonstrated that immunity to Cm is dependent on ChpG in all tested varieties, indicating that ChpG-recognition is conserved in eggplant. ChpG-mediated avirulence interactions were disabled by alanine substitution of serine231 of the serine protease catalytic triad, suggesting that protease activity is required for immune recognition of ChpG. Our study identified ChpG as a novel avirulence protein that is recognized in resistant eggplant varieties and restricts the host range of Cm.
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Affiliation(s)
- Raj Kumar Verma
- Department of Plant Pathology and Weed ResearchAgricultural Research OrganizationVolcani InstituteRishon LeZionIsrael
| | - Doron Teper
- Department of Plant Pathology and Weed ResearchAgricultural Research OrganizationVolcani InstituteRishon LeZionIsrael
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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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Advances in the Characterization of the Mechanism Underlying Bacterial Canker Development and Tomato Plant Resistance. HORTICULTURAE 2022. [DOI: 10.3390/horticulturae8030209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Bacterial canker caused by the Gram-positive actinobacterium Clavibacter michiganensis is one of the most serious bacterial diseases of tomatoes, responsible for 10–100% yield losses worldwide. The pathogen can systemically colonize tomato vascular bundles, leading to wilting, cankers, bird’s eye lesions, and plant death. Bactericidal agents are insufficient for managing this disease, because the pathogen can rapidly migrate through the vascular system of plants and induce systemic symptoms. Therefore, the use of resistant cultivars is necessary for controlling this disease. We herein summarize the pathogenicity of C. michiganensis in tomato plants and the molecular basis of bacterial canker pathogenesis. Moreover, advances in the characterization of resistance to this pathogen in tomatoes are introduced, and the status of genetics-based research is described. Finally, we propose potential future research on tomato canker resistance. More specifically, there is a need for a thorough analysis of the host–pathogen interaction, the accelerated identification and annotation of resistance genes and molecular mechanisms, the diversification of resistance resources or exhibiting broad-spectrum disease resistance, and the production of novel and effective agents for control or prevention. This review provides researchers with the relevant information for breeding tomato cultivars resistant to bacterial cankers.
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Oh EJ, Hwang IS, Park IW, Oh CS. Comparative Genome Analyses of Clavibacter michiganensis Type Strain LMG7333 T Reveal Distinct Gene Contents in Plasmids From Other Clavibacter Species. Front Microbiol 2022; 12:793345. [PMID: 35178040 PMCID: PMC8844524 DOI: 10.3389/fmicb.2021.793345] [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: 10/12/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Clavibacter michiganensis, a Gram-positive, plant-pathogenic bacterium belonging to Actinobacteria, is a causal agent of bacterial canker in tomatoes. Although LMG7333T is the type strain of C. michiganensis, it has not been used in many studies, probably because of a lack of the complete genome sequence being available. Therefore, in this study, the complete genome sequence of this type strain was obtained, and comparative genome analysis was conducted with the genome sequences of two other C. michiganensis strains and type strains of Clavibacter species, of which their complete genome sequences are available. C. michiganensis LMG7333T carries one chromosome and two plasmids, pCM1 and pCM2, like two other C. michiganensis strains. All three chromosomal DNA sequences were almost identical. However, the DNA sequences of two plasmids of LMG7333T are similar to those of UF1, but different from those of NCPPB382, indicating that both plasmids carry distinct gene content among C. michiganensis strains. Moreover, 216 protein-coding sequences (CDSs) were only present in the LMG7333T genome compared with type strains of other Clavibacter species. Among these 216 CDSs, approximately 83% were in the chromosome, whereas others were in both plasmids (more than 6% in pCM1 and 11% in pCM2). However, the ratio of unique CDSs of the total CDSs in both plasmids were approximately 38% in pCM1 and 30% in pCM2, indicating that the high gene content percentage in both plasmids of C. michiganensis are different from those of other Clavibacter species, and plasmid DNAs might be derived from different origins. A virulence assay with C. michiganensis LMG7333T using three different inoculation methods, root-dipping, leaf-clipping, and stem injection, resulted in typical disease symptoms, including wilting and canker in tomato. Altogether, our results indicate that two plasmids of C. michiganensis carry distinct gene content, and the genome information of the type strain LMG7333T will help to understand the genetic diversity of the two plasmids of Clavibacter species, including C. michiganensis.
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Affiliation(s)
- Eom-Ji Oh
- Department of Horticultural Biotechnology, College of Life Science, Kyung Hee University, Yongin, South Korea
| | - In Sun Hwang
- 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
| | - 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
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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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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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