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Chang Z, Ma Z, Su Q, Xia X, Ye W, Li R, Lu G. The Transcriptional Regulator TfmR Directly Regulates Two Pathogenic Pathways in Xanthomonas oryzae pv. oryzicola. Int J Mol Sci 2024; 25:5887. [PMID: 38892073 PMCID: PMC11173191 DOI: 10.3390/ijms25115887] [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: 04/17/2024] [Revised: 05/17/2024] [Accepted: 05/25/2024] [Indexed: 06/21/2024] Open
Abstract
Xanthomonas oryzae pv. oryzicola (Xoc) is a notorious plant pathogen. Like most bacterial pathogens, Xoc has evolved a complex regulatory network to modulate the expression of various genes related to pathogenicity. Here, we have identified TfmR, a transcriptional regulator belonging to the TetR family, as a key player in the virulence mechanisms of this phytopathogenic bacterium. We have demonstrated genetically that tfmR is involved in the hypersensitive response (HR), pathogenicity, motility and extracellular polysaccharide production of this phytopathogenic bacterium. Our investigations extended to exploring TfmR's interaction with RpfG and HrpX, two prominent virulence regulators in Xanthomonas species. We found that TfmR directly binds to the promoter region of RpfG, thereby positively regulating its expression. Notably, constitutive expression of RpfG partly reinstates the pathogenicity compromised by TfmR-deletion mutants. Furthermore, our studies revealed that TfmR also exerts direct positive regulation on the expression of the T3SS regulator HrpX. Similar to RpfG, sustained expression of HrpX partially restores the pathogenicity of TfmR-deletion mutants. These findings underscore TfmR's multifaceted role as a central regulator governing key virulence pathways in Xoc. Importantly, our research sheds light on the intricate molecular mechanisms underlying the regulation of pathogenicity in this plant pathogen.
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Affiliation(s)
- Zheng Chang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China; (Z.C.); (Q.S.); (X.X.); (W.Y.)
- Plant Protection Research Institute, Guangxi Academy of Agricultural Science/Key Laboratory of Green Prevention and Control on Fruits and Vegetables in South China Ministry of Agriculture and Rural Affairs/Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests, Nanning 530007, China
| | - Zengfeng Ma
- Rice Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China;
| | - Qian Su
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China; (Z.C.); (Q.S.); (X.X.); (W.Y.)
| | - Xinqi Xia
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China; (Z.C.); (Q.S.); (X.X.); (W.Y.)
| | - Wenxin Ye
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China; (Z.C.); (Q.S.); (X.X.); (W.Y.)
| | - Ruifang Li
- Plant Protection Research Institute, Guangxi Academy of Agricultural Science/Key Laboratory of Green Prevention and Control on Fruits and Vegetables in South China Ministry of Agriculture and Rural Affairs/Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests, Nanning 530007, China
| | - Guangtao Lu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China; (Z.C.); (Q.S.); (X.X.); (W.Y.)
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Ding J, Liao M, Wang Q. Co-regulation of Thermosensor Pathogenic Factors by C-di-GMP-Related Two-Component Systems and a cAMP Receptor-like Protein (Clp) in Stenotrophomonas maltophilia. Foods 2024; 13:1201. [PMID: 38672874 PMCID: PMC11049440 DOI: 10.3390/foods13081201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 03/31/2024] [Accepted: 04/01/2024] [Indexed: 04/28/2024] Open
Abstract
Stenotrophomonas maltophilia is a major threat to the food industry and human health owing to its strong protease production and biofilm formation abilities. However, information regarding regulatory factors or potential mechanisms is limited. Herein, we observed that temperature differentially regulates biofilm formation and protease production, and a cAMP receptor-like protein (Clp) negatively regulates thermosensor biofilm formation, in contrast to protease synthesis. Among four c-di-GMP-related two-component systems (TCSs), promoter fusion analysis revealed that clp transcription levels were predominantly controlled by LotS/LotR, partially controlled by both RpfC/RpfG and a novel TCS Sm0738/Sm0737, with no obvious effect caused by Sm1912/Sm1911. Biofilm formation in Δclp and ΔTCSs strains suggested that LotS/LotR controlled biofilm formation in a Clp-mediated manner, whereas both RpfC/RpfG and Sm0738/Sm0737 may occur in a distinct pathway. Furthermore, enzymatic activity analysis combined with c-di-GMP level indicated that the enzymatic activity of c-di-GMP-related metabolism proteins may not be a vital contributor to changes in c-di-GMP level, thus influencing physiological functions. Our findings elucidate that the regulatory pathway of c-di-GMP-related TCSs and Clp in controlling spoilage or the formation of potentially pathogenic factors in Stenotrophomonas expand the understanding of c-di-GMP metabolism and provide clues to control risk factors of S. maltophilia in food safety.
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Affiliation(s)
| | | | - Qingling Wang
- Shaanxi Natural Carbohydrate Resource Engineering Research Center, College of Food Science and Technology, Northwest University, Xi’an 710069, China; (J.D.); (M.L.)
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Heiden N, Broders KA, Hutin M, Castro MO, Roman-Reyna V, Toth H, Jacobs JM. Bacterial Leaf Streak Diseases of Plants: Symptom Convergence in Monocot Plants by Distant Pathogenic Xanthomonas Species. PHYTOPATHOLOGY 2023; 113:2048-2055. [PMID: 37996392 DOI: 10.1094/phyto-05-23-0155-ia] [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: 11/25/2023]
Abstract
Bacterial leaf streak (BLS) is a disease of monocot plants caused by Xanthomonas translucens on small grains, X. vasicola on maize and sorghum, and X. oryzae on rice. These three pathogens cause remarkably similar symptomology in their host plants. Despite causing similar symptoms, BLS pathogens are dispersed throughout the larger Xanthomonas phylogeny. Each aforementioned species includes strain groups that do not cause BLS and instead cause vascular disease. In this commentary, we hypothesize that strains of X. translucens, X. vasicola, and X. oryzae convergently evolved to cause BLS due to shared evolutionary pressures. We examined the diversity of secreted effectors, which may be important virulence factors for BLS pathogens and their evolution. We discuss evidence that differences in gene regulation and abilities to manipulate plant hormones may also separate BLS pathogens from other Xanthomonas species or pathovars. BLS is becoming an increasing issue across the three pathosystems. Overall, we hope that a better understanding of conserved mechanisms used by BLS pathogens will enable researchers to translate findings across production systems and guide approaches to control this (re)emerging threat.
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Affiliation(s)
- Nathaniel Heiden
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, U.S.A
- Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Kirk A Broders
- U.S. Department of Agriculture-Agricultural Research Service, National Center for Agricultural Utilization Research, Mycotoxin Prevention and Applied Microbiology Research Unit, Peoria, IL 61604, U.S.A
| | - Mathilde Hutin
- Plant Health Institute of Montpellier, University of Montpellier, IRD, CIRAD, INRAE, Institut Agro, Montpellier, France
| | - Mary Ortiz Castro
- Horticulture and Extension Programs, Colorado State University, Castle Rock, CO 80106, U.S.A
| | - Verónica Roman-Reyna
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, U.S.A
- Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, U.S.A
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, PA 16802, U.S.A
| | - Hannah Toth
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, U.S.A
- Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, U.S.A
| | - Jonathan M Jacobs
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210, U.S.A
- Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210, U.S.A
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Zhao JY, Chen J, Shi Y, Fu HY, Huang MT, Rott PC, Gao SJ. Sugarcane responses to two strains of Xanthomonas albilineans differing in pathogenicity through a differential modulation of salicylic acid and reactive oxygen species. FRONTIERS IN PLANT SCIENCE 2022; 13:1087525. [PMID: 36589125 PMCID: PMC9798216 DOI: 10.3389/fpls.2022.1087525] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Leaf scald caused by Xanthomonas albilineans is one of the major bacterial diseases of sugarcane that threaten the sugar industry worldwide. Pathogenic divergence among strains of X. albilineans and interactions with the sugarcane host remain largely unexplored. In this study, 40 strains of X. albilineans from China were distributed into three distinct evolutionary groups based on multilocus sequence analysis and simple sequence repeats loci markers. In pathogenicity assays, the 40 strains of X. albilineans from China were divided into three pathogenicity groups (low, medium, and high). Twenty-four hours post inoculation (hpi) of leaf scald susceptible variety GT58, leaf populations of X. albilineans strain XaCN51 (high pathogenicity group) determined by qPCR were 3-fold higher than those of strain XaCN24 (low pathogenicity group). Inoculated sugarcane plants modulated the reactive oxygen species (ROS) homoeostasis by enhancing respiratory burst oxidase homolog (ScRBOH) expression and superoxide dismutase (SOD) activity and by decreasing catalase (CAT) activity, especially after infection by X. albilineans XaCN51. Furthermore, at 24 hpi, plants infected with XaCN51 maintained a lower content of endogenous salicylic acid (SA) and a lower expression level of SA-mediated genes (ScNPR3, ScTGA4, ScPR1, and ScPR5) as compared to plants infected with XaCN24. Altogether, these data revealed that the ROS production-scavenging system and activation of the SA pathway were involved in the sugarcane defense response to an attack by X. albilineans.
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Affiliation(s)
- Jian-Ying Zhao
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Juan Chen
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Yang Shi
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Hua-Ying Fu
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Mei-Ting Huang
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Philippe C. Rott
- CIRAD, UMR PHIM, Montpellier, France, and PHIM Plant Health Institute, Univ Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - San-Ji Gao
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
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Li M, Bao Y, Li Y, Akbar S, Wu G, Du J, Wen R, Chen B, Zhang M. Comparative genome analysis unravels pathogenicity of Xanthomonas albilineans causing sugarcane leaf scald disease. BMC Genomics 2022; 23:671. [PMID: 36162999 PMCID: PMC9513982 DOI: 10.1186/s12864-022-08900-2] [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: 06/27/2022] [Accepted: 09/19/2022] [Indexed: 11/28/2022] Open
Abstract
Background Xanthomonas is a genus of gram-negative bacterium containing more than 35 species. Among these pathogenic species, Xanthomonas albilineans (Xal) is of global interest, responsible for leaf scald disease in sugarcane. Another notable Xanthomonas species is Xanthomonas sachari (Xsa), a sugarcane-associated agent of chlorotic streak disease. Result The virulence of 24 Xanthomonas strains was evaluated by disease index (DI) and Area Under Disease Progress Curve (AUDPC) in the susceptible inoculated plants (GT 46) and clustered into three groups of five highly potent, seven mild virulent, and twelve weak virulent strains. The highly potent strain (X. albilineans, Xal JG43) and its weak virulent related strain (X. sacchari, Xsa DD13) were sequenced, assembled, and annotated in the circular genomes. The genomic size of JG43 was smaller than that of DD13. Both strains (JG43 and DD13) lacked a Type III secretory system (T3SS) and T6SS. However, JG43 possessed Salmonella pathogenicity island-1 (SPI-1). More pathogen-host interaction (PHI) genes and virulent factors in 17 genomic islands (GIs) were detected in JG43, among which six were related to pathogenicity. Albicidin and a two-component system associated with virulence were also detected in JG43. Furthermore, 23 Xanthomonas strains were sequenced and classified into three categories based on Single Nucleotide Polymorphism (SNP) mutation loci and pathogenicity, using JG43 as a reference genome. Transitions were dominant SNP mutations, while structural variation (SV) is frequent intrachromosomal rearrangement (ITX). Two essential genes (rpfC/rpfG) of the two-component system and another gene related to SNP were mutated to understand their virulence effect. The mutation of rpfG resulted in a decrease in pathogenicity. Conclusion These findings revealed virulence of 24 Xanthomonas strains and variations by 23 Xanthomonas strains. We sequenced, assembled, and annotated the circular genomes of Xal JG43 and Xsa DD13, identifying diversity detected by pathogenic factors and systems. Furthermore, complete genomic sequences and sequenced data will provide a theoretical basis for identifying pathogenic factors responsible for sugarcane leaf scald disease. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08900-2.
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Affiliation(s)
- MeiLin Li
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - YiXue Bao
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - YiSha Li
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - Sehrish Akbar
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - GuangYue Wu
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - JinXia Du
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - Ronghui Wen
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - Baoshan Chen
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China
| | - MuQing Zhang
- State Key Laboratory of Conservation and Utilization for Subtropical Agri-Biological Resources & Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning, 530005, Guangxi, China.
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Relationship of the CreBC two-component regulatory system and inner membrane protein CreD with swimming motility in Stenotrophomonas maltophilia. PLoS One 2017; 12:e0174704. [PMID: 28437463 PMCID: PMC5402928 DOI: 10.1371/journal.pone.0174704] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 03/14/2017] [Indexed: 01/12/2023] Open
Abstract
The CreBC two-component system (TCS) is a conserved regulatory system found in Escherichia coli, Aeromonas spp., Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. In this study, we determined how CreBC TCS regulates secreted protease activities and swimming motility using creB, creC, and creBC in-frame deletion mutants (KJΔCreB, KJΔCreC, and KJΔBC) of S. maltophilia KJ. Compared to wild-type KJ, KJΔCreB had a comparable secreted protease activity; however, the secreted protease activities were obviously reduced in KJΔCreC and KJΔBC, suggesting that CreC works together with another unidentified response regulator (not CreB) to regulate secreted protease activity. Single gene inactivation of creB or creC resulted in mutants with an enhanced swimming motility, and this phenotype was exacerbated in a double mutant KJΔBC. To elucidate the underlying mechanism responsible for the ΔcreBC-mediated swimming enhancement, flagella morphology observation, RNA-seq based transcriptome assay, qRT-PCR, and membrane integrity and potential assessment were performed. Flagella morphological observation ruled out the possibility that swimming enhancement was due to altered flagella morphology. CreBC inactivation upregulated the expression of creD and flagella-associated genes encoding the basal body- and motor-associated proteins. Furthermore, KJΔBC had an increased membrane susceptibility to Triton X-100 and CreD upregulation in KJΔBC partially alleviated the compromise of membrane integrity. The impact of creBC TCS on bacterial membrane potential was assessed by carbonyl cyanide m-chlorophenyl hydrazine (CCCP50) concentration at which 50% of bacterial swimming is inhibited. CCCP50 of wild-type KJ increased when creBC was deleted, indicating an association between the higher membrane potential of KJΔBC cells and enhanced motility. Upregulation of the basal body- and motor-associated genes of flagella in KJΔBC cells may explain the increased membrane potential. Collectively, inactivation of creBC increased swimming motility through membrane potential increase and creD upregulation in S. maltophilia. The increased membrane potential may supply more energy for flagella propelling and CreD upregulation supports membrane stability, providing a strong membrane for flagellum function.
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Pang X, Liu C, Lyu P, Zhang S, Liu L, Lu J, Ma C, Lv J. Identification of Quorum Sensing Signal Molecule of Lactobacillus delbrueckii subsp. bulgaricus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:9421-9427. [PMID: 27960296 DOI: 10.1021/acs.jafc.6b04016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Many bacteria in nature use quorum sensing (QS) to regulate gene expression. The quorum sensing system plays critical roles in the adaptation of bacteria to the surrounding environment. Previous studies have shown that during high-density fermentation, the autolysis of lactic acid bacteria was regulated by the QS system, and the two-component system (TCS, LBUL_RS00115/LBUL_RS00110) is involved in the autolysis of Lactobacillus delbrueckii subsp. bulgaricus. However, the QS signal molecule, which regulates this pathway, has not been identified. In this study, we compared the genome of Lactobacillus bulgaricus ATCC BAA-365 with the locus of seven lactobacillus QS systems; the position of the QS signal molecule of Lactobacillus bulgaricus ATCC BAA-365 was predicted by bioinformatics tool. Its function was identified by in vitro experiments. Construction of TCS mutant by gene knockout of LBUL_RS00115 confirmed that the signal molecule regulates the density of the flora by the TCS (LBUL_RS00115/LBUL_RS00110). This study indicated that quorum quenching and inhibition based on the signal molecule might serve as an approach to reduce the rate of autolysis of LAB and increase the number of live bacteria in fermentation.
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Affiliation(s)
- Xiaoyang Pang
- State Key Laboratory of Dairy Biotechnology, Shanghai Engineering Research Center of Dairy Biotechnology, Dairy Research Institute, Bright Dairy Company Ltd. , Shanghai 200436, People's Republic of China
- Key Laboratory of Agro-Food Processing and Quality Control, Institute of Agro-Food Science and Technology, Chinese Academy of Agricultural Science , Beijing 100193, People's Republic of China
| | - Cuiping Liu
- State Key Laboratory of Dairy Biotechnology, Shanghai Engineering Research Center of Dairy Biotechnology, Dairy Research Institute, Bright Dairy Company Ltd. , Shanghai 200436, People's Republic of China
| | - Pengcheng Lyu
- College of Life Science and Bioengineering, Beijing University of Technology , Beijing 100124, People's Republic of China
| | - Shuwen Zhang
- Key Laboratory of Agro-Food Processing and Quality Control, Institute of Agro-Food Science and Technology, Chinese Academy of Agricultural Science , Beijing 100193, People's Republic of China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology & Business University (BTBU) , Beijing 100048, People's Republic of China
| | - Lu Liu
- Key Laboratory of Agro-Food Processing and Quality Control, Institute of Agro-Food Science and Technology, Chinese Academy of Agricultural Science , Beijing 100193, People's Republic of China
| | - Jing Lu
- Key Laboratory of Agro-Food Processing and Quality Control, Institute of Agro-Food Science and Technology, Chinese Academy of Agricultural Science , Beijing 100193, People's Republic of China
| | - Changlu Ma
- Beijing Vocational College of Agriculture , Beijing 102442, People's Republic of China
| | - Jiaping Lv
- Key Laboratory of Agro-Food Processing and Quality Control, Institute of Agro-Food Science and Technology, Chinese Academy of Agricultural Science , Beijing 100193, People's Republic of China
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Systematic Mutational Analysis of Histidine Kinase Genes in the Nosocomial Pathogen Stenotrophomonas maltophilia Identifies BfmAK System Control of Biofilm Development. Appl Environ Microbiol 2016; 82:2444-2456. [PMID: 26873318 DOI: 10.1128/aem.03951-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/09/2016] [Indexed: 12/13/2022] Open
Abstract
The Gram-negative bacterium Stenotrophomonas maltophilialives in diverse ecological niches. As a result of its formidable capabilities of forming biofilm and its resistance to multiple antibiotic agents, the bacterium is also a nosocomial pathogen of serious threat to the health of patients whose immune systems are suppressed or compromised. Besides the histidine kinase RpfC, the two-component signal transduction system (TCS), which is the canonical regulatory machinery used by most bacterial pathogens, has never been experimentally investigated inS. maltophilia Here, we annotated 62 putative histidine kinase genes in the S. maltophilia genome and successfully obtained 51 mutants by systematical insertional inactivation. Phenotypic characterization identified a series of mutants with deficiencies in bacterial growth, swimming motility, and biofilm development. A TCS, named here BfmA-BfmK (Smlt4209-Smlt4208), was genetically confirmed to regulate biofilm formation inS. maltophilia Together with interacting partner prediction and chromatin immunoprecipitation screens, six candidate promoter regions bound by BfmA in vivo were identified. We demonstrated that, among them, BfmA acts as a transcription factor that binds directly to the promoter regions of bfmA-bfmK and Smlt0800(acoT), a gene encoding an acyl coenzyme A thioesterase that is associated with biofilm development, and positively controls their transcription. Genome-scale mutational analyses of histidine kinase genes and functional dissection of BfmK-BfmA regulation in biofilm provide genetic information to support more in-depth studies on cellular signaling inS. maltophilia, in the context of developing novel approaches to fight this important bacterial pathogen.
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Mensi I, Daugrois JH, Pieretti I, Gargani D, Fleites LA, Noell J, Bonnot F, Gabriel DW, Rott P. Surface polysaccharides and quorum sensing are involved in the attachment and survival of Xanthomonas albilineans on sugarcane leaves. MOLECULAR PLANT PATHOLOGY 2016; 17:236-246. [PMID: 25962850 PMCID: PMC6638434 DOI: 10.1111/mpp.12276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Xanthomonas albilineans, the causal agent of sugarcane leaf scald, is a bacterial plant pathogen that is mainly spread by infected cuttings and contaminated harvesting tools. However, some strains of this pathogen are known to be spread by aerial means and are able to colonize the phyllosphere of sugarcane before entering the host plant and causing disease. The objective of this study was to identify the molecular factors involved in the survival or growth of X. albilineans on sugarcane leaves. We developed a bioassay to test for the attachment of X. albilineans on sugarcane leaves using tissue-cultured plantlets grown in vitro. Six mutants of strain XaFL07-1 affected in surface polysaccharide production completely lost their capacity to survive on the sugarcane leaf surface. These mutants produced more biofilm in vitro and accumulated more cellular poly-β-hydroxybutyrate than the wild-type strain. A mutant affected in the production of small molecules (including potential biosurfactants) synthesized by non-ribosomal peptide synthetases (NRPSs) attached to the sugarcane leaves as well as the wild-type strain. Surprisingly, the attachment of bacteria on sugarcane leaves varied among mutants of the rpf gene cluster involved in bacterial quorum sensing. Therefore, quorum sensing may affect polysaccharide production, or both polysaccharides and quorum sensing may be involved in the survival or growth of X. albilineans on sugarcane leaves.
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Affiliation(s)
- Imene Mensi
- UMR BGPI, CIRAD, F-34398, Montpellier, France
| | | | | | | | - Laura A Fleites
- Plant Pathology Department, University of Florida, Gainesville, 32611, USA
| | - Julie Noell
- UMR BGPI, CIRAD, F-34398, Montpellier, France
| | | | - Dean W Gabriel
- Plant Pathology Department, University of Florida, Gainesville, 32611, USA
| | - Philippe Rott
- UMR BGPI, CIRAD, F-34398, Montpellier, France
- Plant Pathology Department, University of Florida, Gainesville, 32611, USA
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Mensi I, Vernerey MS, Gargani D, Nicole M, Rott P. Breaking dogmas: the plant vascular pathogen Xanthomonas albilineans is able to invade non-vascular tissues despite its reduced genome. Open Biol 2014; 4:130116. [PMID: 24522883 PMCID: PMC3938051 DOI: 10.1098/rsob.130116] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 01/20/2014] [Indexed: 12/13/2022] Open
Abstract
Xanthomonas albilineans, the causal agent of sugarcane leaf scald, is missing the Hrp type III secretion system that is used by many Gram-negative bacteria to colonize their host. Until now, this pathogen was considered as strictly limited to the xylem of sugarcane. We used confocal laser scanning microscopy, immunocytochemistry and transmission electron microscopy (TEM) to investigate the localization of X. albilineans in diseased sugarcane. Sugarcane plants were inoculated with strains of the pathogen labelled with a green fluorescent protein. Confocal microscopy observations of symptomatic leaves confirmed the presence of the pathogen in the protoxylem and metaxylem; however, X. albilineans was also observed in phloem, parenchyma and bulliform cells of the infected leaves. Similarly, vascular bundles of infected sugarcane stalks were invaded by X. albilineans. Surprisingly, the pathogen was also observed in apparently intact storage cells of the stalk and in intercellular spaces between these cells. Most of these observations made by confocal microscopy were confirmed by TEM. The pathogen exits the xylem following cell wall and middle lamellae degradation, thus creating openings to reach parenchyma cells. This is the first description of a plant pathogenic vascular bacterium invading apparently intact non-vascular plant tissues and multiplying in parenchyma cells.
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Affiliation(s)
- Imène Mensi
- CIRAD, UMR BGPI, TA A-54/K, Montpellier Cedex 5 34398, France
| | | | - Daniel Gargani
- CIRAD, UMR BGPI, TA A-54/K, Montpellier Cedex 5 34398, France
| | - Michel Nicole
- IRD, UMR RPB, BP 64501, Montpellier Cedex 5 34394, France
| | - Philippe Rott
- CIRAD, UMR BGPI, TA A-54/K, Montpellier Cedex 5 34398, France
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