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Shi Y, Cheng T, Cheang QW, Zhao X, Xu Z, Liang Z, Xu L, Wang J. A cyclic di-GMP-binding adaptor protein interacts with a N5-glutamine methyltransferase to regulate the pathogenesis in Xanthomonas citri subsp. citri. MOLECULAR PLANT PATHOLOGY 2024; 25:e13496. [PMID: 39011828 PMCID: PMC11250160 DOI: 10.1111/mpp.13496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 06/04/2024] [Accepted: 07/03/2024] [Indexed: 07/17/2024]
Abstract
The second messenger cyclic diguanylate monophosphate (c-di-GMP) regulates a wide range of bacterial behaviours through diverse mechanisms and binding receptors. Single-domain PilZ proteins, the most widespread and abundant known c-di-GMP receptors in bacteria, act as trans-acting adaptor proteins that enable c-di-GMP to control signalling pathways with high specificity. This study identifies a single-domain PilZ protein, XAC3402 (renamed N5MapZ), from the phytopathogen Xanthomonas citri subsp. citri (Xcc), which modulates Xcc virulence by directly interacting with the methyltransferase HemK. Through yeast two-hybrid, co-immunoprecipitation and immunofluorescent staining, we demonstrated that N5MapZ and HemK interact directly under both in vitro and in vivo conditions, with the strength of the protein-protein interaction decreasing at high c-di-GMP concentrations. This finding distinguishes N5MapZ from other characterized single-domain PilZ proteins, as it was previously known that c-di-GMP enhances the interaction between those single-domain PilZs and their protein partners. This observation is further supported by the fact that the c-di-GMP binding-defective mutant N5MapZR10A can interact with HemK to inhibit the methylation of the class 1 translation termination release factor PrfA. Additionally, we found that HemK plays an important role in Xcc pathogenesis, as the deletion of hemK leads to extensive phenotypic changes, including reduced virulence in citrus plants, decreased motility, production of extracellular enzymes and stress tolerance. Gene expression analysis has revealed that c-di-GMP and the HemK-mediated pathway regulate the expression of multiple virulence effector proteins, uncovering a novel regulatory mechanism through which c-di-GMP regulates Xcc virulence by mediating PrfA methylation via the single-domain PilZ adaptor protein N5MapZ.
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Affiliation(s)
- Yu Shi
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease ControlSouth China Agricultural UniversityGuangzhouChina
- Guangdong Provincial Key Laboratory of Utilization and Conservation of Food and Medicinal Resources in Northern RegionShaoguan UniversityShaoguanChina
| | - Tianfang Cheng
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease ControlSouth China Agricultural UniversityGuangzhouChina
| | - Qing Wei Cheang
- School of Biological SciencesNanyang Technological UniversitySingaporeSingapore
| | - Xiaoyan Zhao
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease ControlSouth China Agricultural UniversityGuangzhouChina
| | - Zeling Xu
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease ControlSouth China Agricultural UniversityGuangzhouChina
| | - Zhao‐Xun Liang
- School of Biological SciencesNanyang Technological UniversitySingaporeSingapore
| | - Linghui Xu
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease ControlSouth China Agricultural UniversityGuangzhouChina
| | - Junxia Wang
- Integrative Microbiology Research Centre, Guangdong Province Key Laboratory of Microbial Signals and Disease ControlSouth China Agricultural UniversityGuangzhouChina
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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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Alexandrino AV, Barcelos MP, Federico LB, da Silva TG, Cavalca LB, de Moraes CHA, Ferreira H, Taft CA, Behlau F, de Paula Silva CHT, Novo-Mansur MTM. GDP-mannose pyrophosphorylase is an efficient target in Xanthomonas citri for citrus canker control. Microbiol Spectr 2024; 12:e0367323. [PMID: 38722158 PMCID: PMC11237706 DOI: 10.1128/spectrum.03673-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 03/20/2024] [Indexed: 06/06/2024] Open
Abstract
Xanthomonas citri subsp. citri (Xcc) is a bacterium that causes citrus canker, an economically important disease that results in premature fruit drop and reduced yield of fresh fruit. In this study, we demonstrated the involvement of XanB, an enzyme with phosphomannose isomerase (PMI) and guanosine diphosphate-mannose pyrophosphorylase (GMP) activities, in Xcc pathogenicity. Additionally, we found that XanB inhibitors protect the host against Xcc infection. Besides being deficient in motility, biofilm production, and ultraviolet resistance, the xanB deletion mutant was unable to cause disease, whereas xanB complementation restored wild-type phenotypes. XanB homology modeling allowed in silico virtual screening of inhibitors from databases, three of them being suitable in terms of absorption, distribution, metabolism, excretion, and toxicity (ADME/Tox) properties, which inhibited GMP (but not PMI) activity of the Xcc recombinant XanB protein in more than 50%. Inhibitors reduced citrus canker severity up to 95%, similarly to copper-based treatment. xanB is essential for Xcc pathogenicity, and XanB inhibitors can be used for the citrus canker control. IMPORTANCE Xcc causes citrus canker, a threat to citrus production, which has been managed with copper, being required a more sustainable alternative for the disease control. XanB was previously found on the surface of Xcc, interacting with the host and displaying PMI and GMP activities. We demonstrated by xanB deletion and complementation that GMP activity plays a critical role in Xcc pathogenicity, particularly in biofilm formation. XanB homology modeling was performed, and in silico virtual screening led to carbohydrate-derived compounds able to inhibit XanB activity and reduce disease symptoms by 95%. XanB emerges as a promising target for drug design for control of citrus canker and other economically important diseases caused by Xanthomonas sp.
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Affiliation(s)
- André Vessoni Alexandrino
- Laboratório de Bioquímica e Biologia Molecular Aplicada (LBBMA), Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil
- Programa de Pós-Graduação em Biotecnologia (PPGBiotec), Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil
| | - Mariana Pegrucci Barcelos
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Leonardo Bruno Federico
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Tamiris Garcia da Silva
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura, Fundecitrus, Araraquara, São Paulo, Brazil
| | - Lúcia Bonci Cavalca
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, UNESP, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
| | - Carlos Henrique Alves de Moraes
- Laboratório de Bioquímica e Biologia Molecular Aplicada (LBBMA), Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil
| | - Henrique Ferreira
- Departamento de Bioquímica e Microbiologia, Instituto de Biociências, UNESP, Universidade Estadual Paulista, Rio Claro, São Paulo, Brazil
| | | | - Franklin Behlau
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura, Fundecitrus, Araraquara, São Paulo, Brazil
| | | | - Maria Teresa Marques Novo-Mansur
- Laboratório de Bioquímica e Biologia Molecular Aplicada (LBBMA), Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil
- Programa de Pós-Graduação em Biotecnologia (PPGBiotec), Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil
- Programa de Pós-Graduação em Genética Evolutiva e Biologia Molecular (PPGGEv), Universidade Federal de São Carlos, São Carlos, São Paulo, Brazil
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Gaurav I, Thakur A, Kumar G, Long Q, Zhang K, Sidu RK, Thakur S, Sarkar RK, Kumar A, Iyaswamy A, Yang Z. Delivery of Apoplastic Extracellular Vesicles Encapsulating Green-Synthesized Silver Nanoparticles to Treat Citrus Canker. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:1306. [PMID: 37110891 PMCID: PMC10146377 DOI: 10.3390/nano13081306] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 06/19/2023]
Abstract
The citrus canker pathogen Xanthomonas axonopodis has caused severe damage to citrus crops worldwide, resulting in significant economic losses for the citrus industry. To address this, a green synthesis method was used to develop silver nanoparticles with the leaf extract of Phyllanthus niruri (GS-AgNP-LEPN). This method replaces the need for toxic reagents, as the LEPN acts as a reducing and capping agent. To further enhance their effectiveness, the GS-AgNP-LEPN were encapsulated in extracellular vesicles (EVs), nanovesicles with a diameter of approximately 30-1000 nm naturally released from different sources, including plant and mammalian cells, and found in the apoplastic fluid (APF) of leaves. When compared to a regular antibiotic (ampicillin), the delivery of APF-EV-GS-AgNP-LEPN and GS-AgNP-LEPN to X. axonopodis pv. was shown to have more significant antimicrobial activity. Our analysis showed the presence of phyllanthin and nirurinetin in the LEPN and found evidence that both could be responsible for antimicrobial activity against X. axonopodis pv. Ferredoxin-NADP+ reductase (FAD-FNR) and the effector protein XopAI play a crucial role in the survival and virulence of X. axonopodis pv. Our molecular docking studies showed that nirurinetin could bind to FAD-FNR and XopAI with high binding energies (-10.32 kcal/mol and -6.13 kcal/mol, respectively) as compared to phyllanthin (-6.42 kcal/mol and -2.93 kcal/mol, respectively), which was also supported by the western blot experiment. We conclude that (a) the hybrid of APF-EV and GS-NP could be an effective treatment for citrus canker, and (b) it works via the nirurinetin-dependent inhibition of FAD-FNR and XopAI in X. axonopodis pv.
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Affiliation(s)
- Isha Gaurav
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong SAR 999077, China
| | - Abhimanyu Thakur
- Ben May Department for Cancer Research, Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - Gaurav Kumar
- Clinical Research Division, Department of Biosciences, School of Basic and Applied Sciences, Galgotias University, Greater Noida 203201, Uttar Pradesh, India
| | - Qin Long
- Citrus Research Institute, Southwest University, Chinese Academy of Agricultural Sciences, National Citrus Engineering Research Center, Chongqing 400712, China
| | - Kui Zhang
- Ben May Department for Cancer Research, Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA
| | - Rakesh Kumar Sidu
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India
| | - Sudha Thakur
- National Institute for Locomotor Disabilities (Divyangjan), Kolkata 700090, India
| | - Rajesh Kumar Sarkar
- Department of Medicine, Division of Biological Sciences, University of Chicago, Chicago, IL 60637, USA
| | - Anoop Kumar
- Department of Pharmacology, Delhi Pharmaceutical Sciences and Research University (DPSRU), New Delhi 110017, India
| | - Ashok Iyaswamy
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong SAR 999077, China
- Mr. & Mrs. Ko Chi-Ming Centre for Parkinson’s Disease Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong SAR 999077, China
- Department of Biochemistry, Karpagam Academy of Higher Education, Coimbatore 641021, India
| | - Zhijun Yang
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong SAR 999077, China
- Changshu Research Institute, Hong Kong Baptist University, Changshu Economic and Technological Development (CETD) Zone, Changshu 215500, China
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Shi Y, Yang X, Ye X, Feng J, Cheng T, Zhou X, Liu DX, Xu L, Wang J. The Methyltransferase HemK Regulates the Virulence and Nutrient Utilization of the Phytopathogenic Bacterium Xanthomonas citri Subsp. citri. Int J Mol Sci 2022; 23:ijms23073931. [PMID: 35409293 PMCID: PMC8999716 DOI: 10.3390/ijms23073931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 03/28/2022] [Accepted: 03/30/2022] [Indexed: 11/18/2022] Open
Abstract
Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri (Xcc), seriously affects fruit quality and yield, leading to significant economic losses around the world. Understanding the mechanism of Xcc virulence is important for the effective control of Xcc infection. In this report, we investigate the role of a protein named HemK in the regulation of the virulence traits of Xcc. The hemK gene was deleted in the Xcc jx-6 background, and the ΔhemK mutant phenotypically displayed significantly decreased motility, biofilm formation, extracellular enzymes, and polysaccharides production, as well as increased sensitivity to oxidative stress and high temperatures. In accordance with the role of HemK in the regulation of a variety of virulence-associated phenotypes, the deletion of hemK resulted in reduced virulence on citrus plants as well as a compromised hypersensitive response on a non-host plant, Nicotiana benthamiana. These results indicated that HemK is required for the virulence of Xcc. To characterize the regulatory effect of hemK deletion on gene expression, RNA sequencing analysis was conducted using the wild-type Xcc jx-6 strain and its isogenic ΔhemK mutant strain, grown in XVM2 medium. Comparative transcriptome analysis of these two strains revealed that hemK deletion specifically changed the expression of several virulence-related genes associated with the bacterial secretion system, chemotaxis, and quorum sensing, and the expression of various genes related to nutrient utilization including amino acid metabolism, carbohydrate metabolism, and energy metabolism. In conclusion, our results indicate that HemK plays an essential role in virulence, the regulation of virulence factor synthesis, and the nutrient utilization of Xcc.
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Affiliation(s)
- Yu Shi
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
| | - Xiaobei Yang
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
| | - Xiaoxin Ye
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
| | - Jiaying Feng
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
| | - Tianfang Cheng
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
| | - Xiaofan Zhou
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
| | - Ding Xiang Liu
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
| | - Linghui Xu
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
- Correspondence: (L.X.); (J.W.)
| | - Junxia Wang
- Integrative Microbiology Research Centre, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; (Y.S.); (X.Y.); (X.Y.); (J.F.); (T.C.); (X.Z.); (D.X.L.)
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
- Correspondence: (L.X.); (J.W.)
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Singh P, Verma RK, Chatterjee S. The diffusible signal factor synthase, RpfF, in Xanthomonas oryzae pv. oryzae is required for the maintenance of membrane integrity and virulence. MOLECULAR PLANT PATHOLOGY 2022; 23:118-132. [PMID: 34704368 PMCID: PMC8659556 DOI: 10.1111/mpp.13148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/03/2021] [Accepted: 09/24/2021] [Indexed: 05/12/2023]
Abstract
The Xanthomonas group of phytopathogens communicate with a fatty acid-like cell-cell signalling molecule, cis-11-2-methyl-dodecenoic acid, also known as diffusible signal factor (DSF). In the pathogen of rice, Xanthomonas oryzae pv. oryzae, DSF is involved in the regulation of several virulence-associated functions, including production and secretion of several cell wall hydrolysing type II secretion effectors. To understand the role of DSF in the secretion of type II effectors, we characterized DSF synthase-deficient (rpfF) and DSF-deficient, type II secretion (xpsE) double mutants. Mutant analysis by expression analysis, secretion assay, fatty acid analysis, and physiological studies indicated that rpfF mutants exhibit hypersecretion of several type II effectors due to a perturbed membrane and DSF is required for maintaining membrane integrity. The rpfF mutants exhibited significantly higher uptake of 1-N-phenylnapthylamine and ethidium bromide, and up-regulation of rpoE (σE ). Increasing the osmolarity of the medium could rescue the hypersecretion phenotype of the rpfF mutant. The rpfF mutant exhibited highly reduced virulence. We report for the first time that in X. oryzae pv. oryzae RpfF is involved in the maintenance of membrane integrity by playing a regulatory role in the fatty acid synthesis pathway.
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Affiliation(s)
- Prashantee Singh
- Laboratory of Plant Microbe InteractionsCentre for DNA Fingerprinting and DiagnosticsUppalIndia
- Graduate StudiesManipal Academy of Higher EducationMangaluruIndia
| | - Raj Kumar Verma
- Laboratory of Plant Microbe InteractionsCentre for DNA Fingerprinting and DiagnosticsUppalIndia
| | - Subhadeep Chatterjee
- Laboratory of Plant Microbe InteractionsCentre for DNA Fingerprinting and DiagnosticsUppalIndia
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Picchi SC, Granato LM, Franzini MJF, Andrade MO, Takita MA, Machado MA, de Souza AA. Modified Monosaccharides Content of Xanthan Gum Impairs Citrus Canker Disease by Affecting the Epiphytic Lifestyle of Xanthomonas citri subsp. citri. Microorganisms 2021; 9:microorganisms9061176. [PMID: 34072545 PMCID: PMC8229982 DOI: 10.3390/microorganisms9061176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/16/2021] [Accepted: 04/22/2021] [Indexed: 11/16/2022] Open
Abstract
Xanthomonas citri subsp. citri (X. citri) is a plant pathogenic bacterium causing citrus canker disease. The xanA gene encodes a phosphoglucomutase/phosphomannomutase protein that is a key enzyme required for the synthesis of lipopolysaccharides and exopolysaccharides in Xanthomonads. In this work, firstly we isolated a xanA transposon mutant (xanA::Tn5) and analyzed its phenotypes as biofilm formation, xanthan gum production, and pathogenesis on the sweet orange host. Moreover, to confirm the xanA role in the impaired phenotypes we further produced a non-polar deletion mutant (ΔxanA) and performed the complementation of both xanA mutants. In addition, we analyzed the percentages of the xanthan gum monosaccharides produced by X. citri wild-type and xanA mutant. The mutant strain had higher ratios of mannose, galactose, and xylose and lower ratios of rhamnose, glucuronic acid, and glucose than the wild-type strain. Such changes in the saccharide composition led to the reduction of xanthan yield in the xanA deficient strain, affecting also other important features in X. citri, such as biofilm formation and sliding motility. Moreover, we showed that xanA::Tn5 caused no symptoms on host leaves after spraying, a method that mimetics the natural infection condition. These results suggest that xanA plays an important role in the epiphytical stage on the leaves that is essential for the successful interaction with the host, including adaptive advantage for bacterial X. citri survival and host invasion, which culminates in pathogenicity.
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Affiliation(s)
- Simone Cristina Picchi
- Biotechnology Lab, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo 1349070, Brazil; (S.C.P.); (M.J.F.F.); (M.A.T.); (M.A.M.)
| | - Laís Moreira Granato
- Biotechnology Lab, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo 1349070, Brazil; (S.C.P.); (M.J.F.F.); (M.A.T.); (M.A.M.)
- Correspondence: (L.M.G.); (A.A.d.S.)
| | - Maria Júlia Festa Franzini
- Biotechnology Lab, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo 1349070, Brazil; (S.C.P.); (M.J.F.F.); (M.A.T.); (M.A.M.)
| | - Maxuel Oliveira Andrade
- Bioscience National Lab, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083100, Brazil;
| | - Marco Aurélio Takita
- Biotechnology Lab, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo 1349070, Brazil; (S.C.P.); (M.J.F.F.); (M.A.T.); (M.A.M.)
| | - Marcos Antonio Machado
- Biotechnology Lab, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo 1349070, Brazil; (S.C.P.); (M.J.F.F.); (M.A.T.); (M.A.M.)
| | - Alessandra Alves de Souza
- Biotechnology Lab, Centro de Citricultura Sylvio Moreira, Instituto Agronômico de Campinas, Cordeirópolis, São Paulo 1349070, Brazil; (S.C.P.); (M.J.F.F.); (M.A.T.); (M.A.M.)
- Correspondence: (L.M.G.); (A.A.d.S.)
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Secrete or perish: The role of secretion systems in Xanthomonas biology. Comput Struct Biotechnol J 2020; 19:279-302. [PMID: 33425257 PMCID: PMC7777525 DOI: 10.1016/j.csbj.2020.12.020] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/13/2020] [Accepted: 12/13/2020] [Indexed: 12/22/2022] Open
Abstract
Bacteria of the Xanthomonas genus are mainly phytopathogens of a large variety of crops of economic importance worldwide. Xanthomonas spp. rely on an arsenal of protein effectors, toxins and adhesins to adapt to the environment, compete with other microorganisms and colonize plant hosts, often causing disease. These protein effectors are mainly delivered to their targets by the action of bacterial secretion systems, dedicated multiprotein complexes that translocate proteins to the extracellular environment or directly into eukaryotic and prokaryotic cells. Type I to type VI secretion systems have been identified in Xanthomonas genomes. Recent studies have unravelled the diverse roles played by the distinct types of secretion systems in adaptation and virulence in xanthomonads, unveiling new aspects of their biology. In addition, genome sequence information from a wide range of Xanthomonas species and pathovars have become available recently, uncovering a heterogeneous distribution of the distinct families of secretion systems within the genus. In this review, we describe the architecture and mode of action of bacterial type I to type VI secretion systems and the distribution and functions associated with these important nanoweapons within the Xanthomonas genus.
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Puławska J, Kałużna M, Warabieda W, Pothier JF, Gétaz M, van der Wolf JM. Transcriptome analysis of Xanthomonas fragariae in strawberry leaves. Sci Rep 2020; 10:20582. [PMID: 33239704 PMCID: PMC7688646 DOI: 10.1038/s41598-020-77612-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 11/09/2020] [Indexed: 11/21/2022] Open
Abstract
Xanthomonas fragariae is a quarantine bacterial pathogen that causes angular leaf spot on strawberry. The aim of our study was to analyse the mechanism of interaction of this bacterium with its host plant at the transcriptome level. For this purpose, mRNAs of X. fragariae growing in Wilbrink’s medium and from infected strawberry cv. Elsanta plants were isolated and sequenced using the Illumina MiSeq platform. The expression profiles of the bacteria in Wilbrink’s medium and in planta were very diverse. Of the 3939 CDSs recorded, 1995 had significantly different expression in planta (966 and 1029 genes were down- and upregulated, respectively). Among the genes showing increased expression in planta, those with eggNOG/COG (evolutionary genealogy of genes: Non-supervised Orthologous Groups/Cluster of Orthologous Groups) categories associated with bacterial cell motility, signal transduction, transport and metabolism of inorganic ions and carbohydrates and transcription were overrepresented. Among the genes with the most increased expression in planta, genes primarily associated with flagella synthesis and chemotaxis were found. It is also interesting to note that out of the 31 genes localized on a plasmid, 16 were expressed differently in planta, which may indicate their potential role in plant–pathogen interactions. Many genes with differentiated expression that were localized on chromosome and plasmid encode proteins of unknown function.
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Affiliation(s)
- Joanna Puławska
- Department of Phytopathology, Research Institute of Horticulture, 96-100, Skierniewice, Poland.
| | - Monika Kałużna
- Department of Phytopathology, Research Institute of Horticulture, 96-100, Skierniewice, Poland
| | - Wojciech Warabieda
- Department of Phytopathology, Research Institute of Horticulture, 96-100, Skierniewice, Poland
| | - Joël F Pothier
- Environmental Genomics and Systems Biology Research Group, Institute for Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), Wädenswil, Switzerland
| | - Michael Gétaz
- Environmental Genomics and Systems Biology Research Group, Institute for Natural Resource Sciences, Zurich University of Applied Sciences (ZHAW), Wädenswil, Switzerland
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10
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Timilsina S, Potnis N, Newberry EA, Liyanapathiranage P, Iruegas-Bocardo F, White FF, Goss EM, Jones JB. Xanthomonas diversity, virulence and plant-pathogen interactions. Nat Rev Microbiol 2020; 18:415-427. [PMID: 32346148 DOI: 10.1038/s41579-020-0361-8] [Citation(s) in RCA: 132] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2020] [Indexed: 12/19/2022]
Abstract
Xanthomonas spp. encompass a wide range of plant pathogens that use numerous virulence factors for pathogenicity and fitness in plant hosts. In this Review, we examine recent insights into host-pathogen co-evolution, diversity in Xanthomonas populations and host specificity of Xanthomonas spp. that have substantially improved our fundamental understanding of pathogen biology. We emphasize the virulence factors in xanthomonads, such as type III secreted effectors including transcription activator-like effectors, type II secretion systems, diversity resulting in host specificity, evolution of emerging strains, activation of susceptibility genes and strategies of host evasion. We summarize the genomic diversity in several Xanthomonas spp. and implications for disease outbreaks, management strategies and breeding for disease resistance.
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Affiliation(s)
- Sujan Timilsina
- Plant Pathology Department, University of Florida, Gainesville, FL, USA
| | - Neha Potnis
- Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Eric A Newberry
- Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | | | | | - Frank F White
- Plant Pathology Department, University of Florida, Gainesville, FL, USA
| | - Erica M Goss
- Plant Pathology Department, University of Florida, Gainesville, FL, USA. .,Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.
| | - Jeffrey B Jones
- Plant Pathology Department, University of Florida, Gainesville, FL, USA.
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11
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Independent Evolution with the Gene Flux Originating from Multiple Xanthomonas Species Explains Genomic Heterogeneity in Xanthomonas perforans. Appl Environ Microbiol 2019; 85:AEM.00885-19. [PMID: 31375496 DOI: 10.1128/aem.00885-19] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/31/2019] [Indexed: 12/31/2022] Open
Abstract
Xanthomonas perforans is the predominant pathogen responsible for bacterial leaf spot of tomato and X. euvesicatoria for that of pepper in the southeast United States. Previous studies have indicated significant changes in the X. perforans population collected from Florida tomato fields over the span of 2 decades, including a shift in race and diversification into three phylogenetic groups driven by genome-wide homologous-recombination events derived from X. euvesicatoria In our sampling of Xanthomonas strains associated with bacterial spot disease in Alabama, we were readily able to isolate X. perforans from symptomatic pepper plants grown in several Alabama counties, indicating a recent shift in the host range of the pathogen. To investigate the diversity of these pepper-pathogenic strains and their relation to populations associated with tomatoes grown in the southeast United States, we sequenced the genomes of eight X. perforans strains isolated from tomatoes and peppers grown in Alabama and compared them with previously published genome data available from GenBank. Surprisingly, reconstruction of the X. perforans core genome revealed the presence of two novel genetic groups in Alabama that each harbored a different transcription activation-like effector (TALE). While one TALE, AvrHah1, was associated with an emergent lineage pathogenic to both tomato and pepper, the other was identified as a new class within the AvrBs3 family, here designated PthXp1, and was associated with enhanced symptom development on tomato. Examination of patterns of homologous recombination across the larger X. euvesicatoria species complex revealed a dynamic pattern of gene flow, with multiple donors of Xanthomonas spp. associated with diverse hosts of isolation.IMPORTANCE Bacterial leaf spot of tomato and pepper is an endemic plant disease with a global distribution. In this study, we investigated the evolutionary processes leading to the emergence of novel X. perforans lineages identified in Alabama. While one lineage was isolated from symptomatic tomato and pepper plants, confirming the host range expansion of X. perforans, the other lineage was isolated from tomato and acquired a novel transcription activation-like effector, here designated PthXp1. Functional analysis of PthXp1 indicated that it does not induce Bs4-mediated resistance in tomato and contributes to virulence, providing an adaptive advantage to strains on tomato. Our findings also show that different phylogenetic groups of the pathogen have experienced independent recombination events originating from multiple Xanthomonas species. This suggests a continuous gene flux between related xanthomonads associated with diverse plant hosts that results in the emergence of novel pathogen lineages and associated phenotypes, including host range.
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12
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The ecnA Antitoxin Is Important Not Only for Human Pathogens: Evidence of Its Role in the Plant Pathogen Xanthomonas citri subsp. citri. J Bacteriol 2019; 201:JB.00796-18. [PMID: 31358614 DOI: 10.1128/jb.00796-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 07/24/2019] [Indexed: 11/20/2022] Open
Abstract
Xanthomonas citri subsp. citri causes citrus canker disease worldwide in most commercial varieties of citrus. Its transmission occurs mainly by wind-driven rain. Once X. citri reaches a leaf, it can epiphytically survive by forming a biofilm, which enhances the persistence of the bacteria under different environmental stresses and plays an important role in the early stages of host infection. Therefore, the study of genes involved in biofilm formation has been an important step toward understanding the bacterial strategy for survival in and infection of host plants. In this work, we show that the ecnAB toxin-antitoxin (TA) system, which was previously identified only in human bacterial pathogens, is conserved in many Xanthomonas spp. We further show that in X. citri, ecnA is involved in important processes, such as biofilm formation, exopolysaccharide (EPS) production, and motility. In addition, we show that ecnA plays a role in X. citri survival and virulence in host plants. Thus, this mechanism represents an important bacterial strategy for survival under stress conditions.IMPORTANCE Very little is known about TA systems in phytopathogenic bacteria. ecnAB, in particular, has only been studied in bacterial human pathogens. Here, we showed that it is present in a wide range of Xanthomonas sp. phytopathogens; moreover, this is the first work to investigate the functional role of this TA system in Xanthomonas citri biology, suggesting an important new role in adaptation and survival with implications for bacterial pathogenicity.
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13
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Garita-Cambronero J, Sena-Vélez M, Ferragud E, Sabuquillo P, Redondo C, Cubero J. Xanthomonas citri subsp. citri and Xanthomonas arboricola pv. pruni: Comparative analysis of two pathogens producing similar symptoms in different host plants. PLoS One 2019; 14:e0219797. [PMID: 31318915 PMCID: PMC6639005 DOI: 10.1371/journal.pone.0219797] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 07/01/2019] [Indexed: 01/06/2023] Open
Abstract
Comparative studies in Xanthomonas have provided a vast amount of data that enabled to deepen in the knowledge of those factors associated with virulence and Xanthomonas plant interaction. The species of this genus present a wide range of host plants and a large number of studies have been focused to elucidate which mechanism are involved in this characteristic. In this study, comparative genomic and phenotypic analysis were performed between X. citri subsp. citri (Xcc), one of the most studied pathogens within Xanthomonas, and X. arboricola pv. pruni (Xap), a pathogen which has aroused great interest in recent time. The work was aimed to find those elements that contribute to their host divergence despite the convergence in the symptoms that each species cause on Citrus spp. and Prunus spp., respectively. This study reveals a set of genes that could be putatively associated with the adaptation of these pathogens to their hosts, being the most remarkable those involved in environmental sensing systems such as the case of the TonB-dependent transporters, the sensors of the two-component system and the methyl accepting chemotaxis proteins. Other important variants were found in processes related to the decomposition of the cell wall as could be appreciated by their dissimilar set of cell-wall degrading enzymes. Type three effectors, as one of the most important factors in delineating the host specificity in Xanthomonas, also showed a different array when comparing both species, being some of them unique to each pathogen. On the other hand, only small variations could be connected to other features such as the motility appendages and surface adhesion proteins, but these differences were accompanied by a dissimilar capacity to attach on host and non-host leaf surface. The molecular factors found in this work provide the basis to perform a more in-depth functional analyses that unveil those actual factors associated with pathogenesis and host specificity in Xcc and Xap.
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Affiliation(s)
- Jerson Garita-Cambronero
- Departamento de Protección Vegetal, Laboratorio Bacteriología, Instituto Nacional de Investigación y Tecnología Agraria (INIA), Madrid, Spain.,Centro de Investigación de Biocombustibles y Bioproductos, Instituto Tecnológico Agrario de Castilla y León (ITACyL), Villarejo de Órbigo, Leon, Spain
| | - Marta Sena-Vélez
- Departamento de Protección Vegetal, Laboratorio Bacteriología, Instituto Nacional de Investigación y Tecnología Agraria (INIA), Madrid, Spain.,Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Elisa Ferragud
- Departamento de Protección Vegetal, Laboratorio Bacteriología, Instituto Nacional de Investigación y Tecnología Agraria (INIA), Madrid, Spain
| | - Pilar Sabuquillo
- Departamento de Protección Vegetal, Laboratorio Bacteriología, Instituto Nacional de Investigación y Tecnología Agraria (INIA), Madrid, Spain
| | - Cristina Redondo
- Departamento de Protección Vegetal, Laboratorio Bacteriología, Instituto Nacional de Investigación y Tecnología Agraria (INIA), Madrid, Spain
| | - Jaime Cubero
- Departamento de Protección Vegetal, Laboratorio Bacteriología, Instituto Nacional de Investigación y Tecnología Agraria (INIA), Madrid, Spain
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14
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Wei C, Ding T, Chang C, Yu C, Li X, Liu Q. Global Regulator PhoP is Necessary for Motility, Biofilm Formation, Exoenzyme Production and Virulence of Xanthomonas citri Subsp. citri on Citrus Plants. Genes (Basel) 2019; 10:genes10050340. [PMID: 31064142 PMCID: PMC6562643 DOI: 10.3390/genes10050340] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 04/28/2019] [Accepted: 05/02/2019] [Indexed: 01/27/2023] Open
Abstract
Citrus canker caused by Xanthomonas citri subsp. citri is one of the most important bacterial diseases of citrus, impacting both plant growth and fruit quality. Identifying and elucidating the roles of genes associated with pathogenesis has aided our understanding of the molecular basis of citrus-bacteria interactions. However, the complex virulence mechanisms of X. citri subsp. citri are still not well understood. In this study, we characterized the role of PhoP in X. citri subsp. citri using a phoP deletion mutant, ΔphoP. Compared with wild-type strain XHG3, ΔphoP showed reduced motility, biofilm formation, as well as decreased production of cellulase, amylase, and polygalacturonase. In addition, the virulence of ΔphoP on citrus leaves was significantly decreased. To further understand the virulence mechanisms of X. citri subsp. citri, high-throughput RNA sequencing technology (RNA-Seq) was used to compare the transcriptomes of the wild-type and mutant strains. Analysis revealed 1017 differentially-expressed genes (DEGs), of which 614 were up-regulated and 403 were down-regulated in ΔphoP. Gene ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that the DEGs were enriched in flagellar assembly, two-component systems, histidine metabolism, bacterial chemotaxis, ABC transporters, and bacterial secretion systems. Our results showed that PhoP activates the expression of a large set of virulence genes, including 22 type III secretion system genes and 15 type III secretion system effector genes, as well as several genes involved in chemotaxis, and flagellar and histidine biosynthesis. Two-step reverse-transcription polymerase chain reaction analysis targeting 17 genes was used to validate the RNA-seq data, and confirmed that the expression of all 17 genes, except for that of virB1, decreased significantly. Our results suggest that PhoP interacts with a global signaling network to co-ordinate the expression of multiple virulence factors involved in modification and adaption to the host environment during infection.
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Affiliation(s)
- Chudan Wei
- College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
| | - Tian Ding
- Guangzhou Airport Entry-Exit Inspection and Quarantine Bureau, Guangzhou 510800, China.
| | - Changqing Chang
- College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Guangzhou 510642, China.
| | - Chengpeng Yu
- College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
| | - Xingwei Li
- College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
| | - Qiongguang Liu
- College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
- State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Guangzhou 510642, China.
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15
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Abstract
Type II secretion (T2S) is one means by which Gram-negative pathogens secrete proteins into the extracellular milieu and/or host organisms. Based upon recent genome sequencing, it is clear that T2S is largely restricted to the Proteobacteria, occurring in many, but not all, genera in the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria classes. Prominent human and/or animal pathogens that express a T2S system(s) include Acinetobacter baumannii, Burkholderia pseudomallei, Chlamydia trachomatis, Escherichia coli, Klebsiella pneumoniae, Legionella pneumophila, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Vibrio cholerae, and Yersinia enterocolitica T2S-expressing plant pathogens include Dickeya dadantii, Erwinia amylovora, Pectobacterium carotovorum, Ralstonia solanacearum, Xanthomonas campestris, Xanthomonas oryzae, and Xylella fastidiosa T2S also occurs in nonpathogenic bacteria, facilitating symbioses, among other things. The output of a T2S system can range from only one to dozens of secreted proteins, encompassing a diverse array of toxins, degradative enzymes, and other effectors, including novel proteins. Pathogenic processes mediated by T2S include the death of host cells, degradation of tissue, suppression of innate immunity, adherence to host surfaces, biofilm formation, invasion into and growth within host cells, nutrient assimilation, and alterations in host ion flux. The reach of T2S is perhaps best illustrated by those bacteria that clearly use it for both environmental survival and virulence; e.g., L. pneumophila employs T2S for infection of amoebae, growth within lung cells, dampening of cytokines, and tissue destruction. This minireview provides an update on the types of bacteria that have T2S, the kinds of proteins that are secreted via T2S, and how T2S substrates promote infection.
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16
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Zhou X, Yan Q, Wang N. Deciphering the regulon of a GntR family regulator via transcriptome and ChIP-exo analyses and its contribution to virulence in Xanthomonas citri. MOLECULAR PLANT PATHOLOGY 2017; 18:249-262. [PMID: 26972728 PMCID: PMC6638223 DOI: 10.1111/mpp.12397] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/08/2016] [Accepted: 03/07/2016] [Indexed: 05/14/2023]
Abstract
Xanthomonas contains a large group of plant-associated species, many of which cause severe diseases on important crops worldwide. Six gluconate-operon repressor (GntR) family transcriptional regulators are predicted in Xanthomonas, one of which, belonging to the YtrA subfamily, plays a prominent role in bacterial virulence. However, the direct targets and comprehensive regulatory profile of YtrA remain unknown. Here, we performed microarray and high-resolution chromatin immunoprecipitation-exonuclease (ChIP-exo) experiments to identify YtrA direct targets and its DNA binding motif in X. citri ssp. citri (Xac), the causal agent of citrus canker. Integrative microarray and ChIP-exo data analysis revealed that YtrA directly regulates three operons by binding to a palindromic motif GGTG-N16 -CACC at the promoter region. A similar palindromic motif and YtrA homologues were also identified in many other bacteria, including Stenotrophomonas, Pseudoxanthomonas and Frateuria, indicating a widespread phenomenon. Deletion of ytrA in Xac abolishes bacterial virulence and induction of the hypersensitive response (HR). We found that YtrA regulates the expression of hrp/hrc genes encoding the bacterial type III secretion system (T3SS) and controls multiple biological processes, including motility and adhesion, oxidative stress, extracellular enzyme production and iron uptake. YtrA represses the expression of its direct targets in artificial medium or in planta. Importantly, over-expression of yro3, one of the YtrA directly regulated operons which contains trmL and XAC0231, induced weaker canker symptoms and down-regulation of hrp/hrc gene expression, suggesting a negative regulation in Xac virulence and T3SS. Our study has significantly advanced the mechanistic understanding of YtrA regulation and its contribution to bacterial virulence.
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Affiliation(s)
- Xiaofeng Zhou
- Citrus Research and Education CenterDepartment of Microbiology and Cell Science, IFAS, University of Florida700 Experiment Station RoadLake AlfredFL33850USA
| | - Qing Yan
- Citrus Research and Education CenterDepartment of Microbiology and Cell Science, IFAS, University of Florida700 Experiment Station RoadLake AlfredFL33850USA
| | - Nian Wang
- Citrus Research and Education CenterDepartment of Microbiology and Cell Science, IFAS, University of Florida700 Experiment Station RoadLake AlfredFL33850USA
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17
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Bonomi HR, Toum L, Sycz G, Sieira R, Toscani AM, Gudesblat GE, Leskow FC, Goldbaum FA, Vojnov AA, Malamud F. Xanthomonas campestris attenuates virulence by sensing light through a bacteriophytochrome photoreceptor. EMBO Rep 2016; 17:1565-1577. [PMID: 27621284 DOI: 10.15252/embr.201541691] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 08/02/2016] [Indexed: 11/09/2022] Open
Abstract
Phytochromes constitute a major photoreceptor family found in plants, algae, fungi, and prokaryotes, including pathogens. Here, we report that Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot disease which affects cruciferous crops worldwide, codes for a functional bacteriophytochrome (XccBphP). XccBphP possesses an N-terminal PAS2-GAF-PHY photosensory domain triad and a C-terminal PAS9 domain as its output module. Our results show that illumination of Xcc, prior to plant infection, attenuates its virulence in an XccBphP-dependent manner. Moreover, in response to light, XccBphP downregulates xanthan exopolysaccharide production and biofilm formation, two known Xcc virulence factors. Furthermore, the XccbphP null mutant shows enhanced virulence, similar to that of dark-adapted Xcc cultures. Stomatal aperture regulation and callose deposition, both well-established plant defense mechanisms against bacterial pathogens, are overridden by the XccbphP strain. Additionally, an RNA-Seq analysis reveals that far-red light or XccBphP overexpression produces genomewide transcriptional changes, including the inhibition of several Xcc virulence systems. Our findings indicate that Xcc senses light through XccBphP, eliciting bacterial virulence attenuation via downregulation of bacterial virulence factors. The capacity of XccBphP to respond to light both in vitro and in vivo was abolished by a mutation on the conserved Cys13 residue. These results provide evidence for a novel bacteriophytochrome function affecting an infectious process.
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Affiliation(s)
- Hernán R Bonomi
- Fundación Instituto Leloir - IIBBA CONICET, Buenos Aires, Argentina
| | - Laila Toum
- Instituto de Ciencia y Tecnología Dr. Cesar Milstein, Fundación Pablo Cassará, CONICET, Buenos Aires, Argentina
| | - Gabriela Sycz
- Fundación Instituto Leloir - IIBBA CONICET, Buenos Aires, Argentina
| | - Rodrigo Sieira
- Fundación Instituto Leloir - IIBBA CONICET, Buenos Aires, Argentina
| | - Andrés M Toscani
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gustavo E Gudesblat
- Instituto de Ciencia y Tecnología Dr. Cesar Milstein, Fundación Pablo Cassará, CONICET, Buenos Aires, Argentina
| | - Federico C Leskow
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | | | - Adrián A Vojnov
- Instituto de Ciencia y Tecnología Dr. Cesar Milstein, Fundación Pablo Cassará, CONICET, Buenos Aires, Argentina
| | - Florencia Malamud
- Instituto de Ciencia y Tecnología Dr. Cesar Milstein, Fundación Pablo Cassará, CONICET, Buenos Aires, Argentina .,UNSAM Campus Miguelete IIB - Instituto de Investigaciones Biotecnológicas, Buenos Aires, Argentina
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18
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Identification of an Extracellular Endoglucanase That Is Required for Full Virulence in Xanthomonas citri subsp. citri. PLoS One 2016; 11:e0151017. [PMID: 26950296 PMCID: PMC4780785 DOI: 10.1371/journal.pone.0151017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 02/23/2016] [Indexed: 01/04/2023] Open
Abstract
Xanthomonas citri subsp. citri causes citrus canker disease, which is characterized by the formation of water-soaked lesions, white or yellow spongy pustules and brown corky canker. In this work, we report the contribution of extracellular endoglucanase to canker development during infection. The ectopic expression of nine putative cellulases in Escherichia coli indicated that two endoglucanases, BglC3 and EngXCA, show carboxymethyl cellulase activity. Both bglC3 and engXCA genes were transcribed in X. citri subsp. citri, however, only BglC3 protein was detected outside the cell in western blot analysis. The deletion of bglC3 gene resulted in complete loss of extracellular carboxymethyl cellulase activity and delayed the onset of canker symptoms in both infiltration- and wound-inoculation assays. When growing in plant tissue, the cell density of bglC3 mutant was lower than that of the wild type. Our data demonstrated that BglC3 is an extracellular endoglucanase required for the full virulence of X. citri subsp. citri.
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19
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Enzymatic Activity and Susceptibility to Antifungal Agents of Brazilian Environmental Isolates of Hortaea werneckii. Mycopathologia 2015; 180:345-52. [DOI: 10.1007/s11046-015-9920-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 06/30/2015] [Indexed: 10/23/2022]
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20
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Xanthomonas campestris pv. vesicatoria Secretes Proteases and Xylanases via the Xps Type II Secretion System and Outer Membrane Vesicles. J Bacteriol 2015; 197:2879-93. [PMID: 26124239 DOI: 10.1128/jb.00322-15] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 06/19/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Many plant-pathogenic bacteria utilize type II secretion (T2S) systems to secrete degradative enzymes into the extracellular milieu. T2S substrates presumably mediate the degradation of plant cell wall components during the host-pathogen interaction and thus promote bacterial virulence. Previously, the Xps-T2S system from Xanthomonas campestris pv. vesicatoria was shown to contribute to extracellular protease activity and the secretion of a virulence-associated xylanase. The identities and functions of additional T2S substrates from X. campestris pv. vesicatoria, however, are still unknown. In the present study, the analysis of 25 candidate proteins from X. campestris pv. vesicatoria led to the identification of two type II secreted predicted xylanases, a putative protease and a lipase which was previously identified as a virulence factor of X. campestris pv. vesicatoria. Studies with mutant strains revealed that the identified xylanases and the protease contribute to virulence and in planta growth of X. campestris pv. vesicatoria. When analyzed in the related pathogen X. campestris pv. campestris, several T2S substrates from X. campestris pv. vesicatoria were secreted independently of the T2S systems, presumably because of differences in the T2S substrate specificities of the two pathogens. Furthermore, in X. campestris pv. vesicatoria T2S mutants, secretion of T2S substrates was not completely absent, suggesting the contribution of additional transport systems to protein secretion. In line with this hypothesis, T2S substrates were detected in outer membrane vesicles, which were frequently observed for X. campestris pv. vesicatoria. We, therefore, propose that extracellular virulence-associated enzymes from X. campestris pv. vesicatoria are targeted to the Xps-T2S system and to outer membrane vesicles. IMPORTANCE The virulence of plant-pathogenic bacteria often depends on TS2 systems, which secrete degradative enzymes into the extracellular milieu. T2S substrates are being studied in several plant-pathogenic bacteria, including Xanthomonas campestris pv. vesicatoria, which causes bacterial spot disease in tomato and pepper. Here, we show that the T2S system from X. campestris pv. vesicatoria secretes virulence-associated xylanases, a predicted protease, and a lipase. Secretion assays with the related pathogen X. campestris pv. campestris revealed important differences in the T2S substrate specificities of the two pathogens. Furthermore, electron microscopy showed that T2S substrates from X. campestris pv. vesicatoria are targeted to outer membrane vesicles (OMVs). Our results, therefore, suggest that OMVs provide an alternative transport route for type II secreted extracellular enzymes.
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21
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Identification of seven novel virulence genes from Xanthomonas citri subsp. citri by Tn5-based random mutagenesis. J Microbiol 2015; 53:330-6. [PMID: 25935304 DOI: 10.1007/s12275-015-4589-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 03/03/2015] [Accepted: 03/28/2015] [Indexed: 10/23/2022]
Abstract
To identify novel virulence genes, a mutant library of Xanthomonas citri subsp. citri 29-1 was produced using EZ-Tn5 transposon and the mutants were inoculated into susceptible grapefruit. Forty mutants with altered virulence phenotypes were identified. Nine of the mutants showed a complete loss of citrus canker induction, and the other 31 mutants resulted in attenuated canker symptoms. Southern blot analysis revealed that each of the mutants carried a single copy of Tn5. The flanking sequence was identified by plasmid rescue and 18 different ORFs were identified in the genome sequence. Of these 18 ORFs, seven had not been previously associated with the virulence of X. citri subsp. citri and were therefore confirmed by complementation analysis. Real-time PCR analysis showed that the seven genes were upregulated when the bacteria were grown in citrus plants, suggesting that the expression of these genes was essential for canker development.
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Malamud F, Homem RA, Conforte VP, Yaryura PM, Castagnaro AP, Marano MR, do Amaral AM, Vojnov AA. Identification and characterization of biofilm formation-defective mutants of Xanthomonas citri subsp. citri. Microbiology (Reading) 2013; 159:1911-1919. [DOI: 10.1099/mic.0.064709-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Florencia Malamud
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Rafael Augusto Homem
- Embrapa Recursos Genéticos e Biotecnología and Centro APTA Citros Sylvio Moreira, Instituto Agronômico de Campinas, Cordeiropolis, Sao Pablo, Brazil
| | - Valeria Paola Conforte
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Pablo Marcelo Yaryura
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Atilio Pedro Castagnaro
- Estación Experimental Agroindustrial Obispo Colombres, Av. William Cross 3150, Las Talitas, Tucumán, Argentina
| | - María Rosa Marano
- IBR-Depto Microbiología, Facultad de Ciencias, Bioquímicas y Farmacéuticas, U.N.R. Suipacha 531, S2002LRK Rosario, Argentina
| | - Alexandre Morais do Amaral
- Embrapa Recursos Genéticos e Biotecnología and Centro APTA Citros Sylvio Moreira, Instituto Agronômico de Campinas, Cordeiropolis, Sao Pablo, Brazil
| | - Adrián Alberto Vojnov
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
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Chiesa MA, Siciliano MF, Ornella L, Roeschlin RA, Favaro MA, Delgado NP, Sendín LN, Orce IG, Ploper LD, Vojnov AA, Vacas JG, Filippone MP, Castagnaro AP, Marano MR. Characterization of a variant of Xanthomonas citri subsp. citri that triggers a host-specific defense response. PHYTOPATHOLOGY 2013; 103:555-564. [PMID: 23268580 DOI: 10.1094/phyto-11-12-0287-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Citrus is an economically important fruit crop that is severely afflicted by Asiatic citrus bacterial canker (CBC), a disease caused by the phytopathogen Xanthomonas citri subsp. citri (X. citri). To gain insight into the molecular epidemiology of CBC, 42 Xanthomonas isolates were collected from a range of Citrus spp. across 17 different orchards in Tucumán, Argentina and subjected to molecular, biochemical, and pathogenicity tests. Analysis of genome-specific X. citri markers and DNA polymorphisms based on repetitive elements-based polymerase chain reaction showed that all 42 isolates belonged to X. citri. Interestingly, pathogenicity tests showed that one isolate, which shares >90% genetic similarity to the reference strain X. citri T, has host range specificity. This new variant of X. citri subsp. citri, named X. citri A(T), which is deficient in xanthan production, induces an atypical, noncankerous chlorotic phenotype in Citrus limon and C. paradisi and weak cankerous lesions in C. aurantifolia and C. clementina leaves. In C. limon, suppression of canker development is concomitant with an oxidative burst; xanthan is not implicated in the phenotype induced by this interaction, suggesting that other bacterial factors would be involved in triggering the defense response.
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Affiliation(s)
- María A Chiesa
- Instituto de Biología Molecular y Celular de Rosario (IBR)–Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Área Virología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 590, S2002LRK Rosario, Argentina
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Yan Q, Wang N. High-throughput screening and analysis of genes of Xanthomonas citri subsp. citri involved in citrus canker symptom development. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:69-84. [PMID: 21899385 DOI: 10.1094/mpmi-05-11-0121] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Citrus canker is caused by Xanthomonas citri subsp. citri and is one of the most devastating diseases on citrus plants. To investigate the virulence mechanism of this pathogen, a mutant library of strain 306 containing approximately 22,000 mutants was screened for virulence-deficient mutants in grapefruit (Citrus paradise). Eighty-two genes were identified that contribute to citrus canker symptom development caused by X. citri subsp. citri. Among the 82 identified genes, 23 genes were classified as essential genes, as mutation of these genes caused severe reduction of bacterial growth in M9 medium. The remaining 59 genes were classified as putative virulence-related genes that include 32 previously reported virulence-related genes and 27 novel genes. The 32 known virulence-related genes include genes that are involved in the type III secretion system (T3SS) and T3SS effectors, the quorum-sensing system, extracellular polysaccharide and lipopolysaccharide synthesis, and general metabolic pathways. The contribution to pathogenesis by nine genes (pthA4, trpG, trpC, purD, hrpM, peh-1, XAC1230, XAC1548, and XAC3049) was confirmed by complementation assays. We further validated the mutated genes and their phenotypes by analyzing the EZ-Tn5 insertion copy number using Southern blot analysis. In conclusion, we have significantly advanced our understanding of the putative genetic determinants of the virulence mechanism of X. citri subsp. citri by identifying 59 putative virulence-related genes, including 27 novel genes.
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Affiliation(s)
- Qing Yan
- Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL, USA
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