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Terazawa Y, Tsuzuki M, Nakajima H, Inoue K, Tateda S, Kiba A, Ohnishi K, Kai K, Hikichi Y. The Micacocidin Production-Related RSc1806 Deletion Alters the Quorum Sensing-Dependent Gene Regulation of Ralstonia pseudosolanacearum Strain OE1-1. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:467-476. [PMID: 38805410 DOI: 10.1094/mpmi-12-23-0203-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
The soil-borne phytopathogenic gram-negative bacterium Ralstonia solanacearum species complex (RSSC) produces staphyloferrin B and micacocidin as siderophores that scavenge for trivalent iron (Fe3+) in the environment, depending on the intracellular divalent iron (Fe2+) concentration. The staphyloferrin B-deficient mutant reportedly retains its virulence, but the relationship between micacocidin and virulence remains unconfirmed. To elucidate the effect of micacocidin on RSSC virulence, we generated the micacocidin productivity-deficient mutant (ΔRSc1806) that lacks RSc1806, which encodes a putative polyketide synthase/non-ribosomal peptide synthetase, using the RSSC phylotype I Ralstonia pseudosolanacearum strain OE1-1. When incubated in the condition without Fe2+, ΔRSc1806 showed significantly lower Fe3+-scavenging activity, compared with OE1-1. Until 8 days after inoculation on tomato plants, ΔRSc1806 was not virulent, similar to the mutant (ΔphcA) missing phcA, which encodes the LysR-type transcriptional regulator PhcA that regulates the expression of the genes responsible for quorum sensing (QS)-dependent phenotypes including virulence. The transcriptome analysis revealed that RSc1806 deletion significantly altered the expression of more than 80% of the PhcA-regulated genes in the mutant grown in medium with or without Fe2+. Among the PhcA-regulated genes, the transcript levels of the genes whose expression was affected by the deletion of RSc1806 were strongly and positively correlated between the ΔRSc1806 and the phcA-deletion mutant. Furthermore, the deletion of RSc1806 significantly modified QS-dependent phenotypes, similar to the effects of the deletion of phcA. Collectively, our findings suggest that the deletion of micacocidin production-related RSc1806 alters the regulation of PhcA-regulated genes responsible for QS-dependent phenotypes including virulence as well as Fe3+-scavenging activity. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Yuki Terazawa
- Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Masayuki Tsuzuki
- Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Hiroto Nakajima
- Graduate School of Agriculture, Osaka Metropolitan University, Sakai, Osaka 599-8531, Japan
| | - Kanako Inoue
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Sora Tateda
- Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Akinori Kiba
- Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Kouhei Ohnishi
- Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan
| | - Kenji Kai
- Graduate School of Agriculture, Osaka Metropolitan University, Sakai, Osaka 599-8531, Japan
| | - Yasufumi Hikichi
- Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan
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Cai L, Jain M, Munoz-Bodnar A, Huguet-Tapia JC, Gabriel DW. A synthetic 'essentialome' for axenic culturing of 'Candidatus Liberibacter asiaticus'. BMC Res Notes 2022; 15:125. [PMID: 35365194 PMCID: PMC8973516 DOI: 10.1186/s13104-022-05986-5] [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: 12/09/2021] [Accepted: 02/23/2022] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE 'Candidatus Liberibacter asiaticus' (CLas) is associated with the devastating citrus 'greening' disease. All attempts to achieve axenic growth and complete Koch's postulates with CLas have failed to date, at best yielding complex cocultures with very low CLas titers detectable only by PCR. Reductive genome evolution has rendered all pathogenic 'Ca. Liberibacter' spp. deficient in multiple key biosynthetic, metabolic and structural pathways that are highly unlikely to be rescued in vitro by media supplementation alone. By contrast, Liberibacter crescens (Lcr) is axenically cultured and its genome is both syntenic and highly similar to CLas. Our objective is to achieve replicative axenic growth of CLas via addition of missing culturability-related Lcr genes. RESULTS Bioinformatic analyses identified 405 unique ORFs in Lcr but missing (or truncated) in all 24 sequenced CLas strains. Site-directed mutagenesis confirmed and extended published EZ-Tn5 mutagenesis data, allowing elimination of 310 of these 405 genes as nonessential, leaving 95 experimentally validated Lcr genes as essential for CLas growth in axenic culture. Experimental conditions for conjugation of large GFP-expressing plasmids from Escherichia coli to Lcr were successfully established for the first time, providing a practical method for transfer of large groups of 'essential' Lcr genes to CLas.
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Affiliation(s)
- Lulu Cai
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | - Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | | | - Jose C Huguet-Tapia
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA.
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Cai L, Jain M, Sena-Vélez M, Jones KM, Fleites LA, Heck M, Gabriel DW. Tad pilus-mediated twitching motility is essential for DNA uptake and survival of Liberibacters. PLoS One 2021; 16:e0258583. [PMID: 34644346 PMCID: PMC8513845 DOI: 10.1371/journal.pone.0258583] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/01/2021] [Indexed: 12/12/2022] Open
Abstract
Axenically cultured Liberibacter crescens (Lcr) is a closely related surrogate for uncultured plant pathogenic species of the genus Liberibacter, including ‘Candidatus L. asiaticus’ (CLas) and ‘Ca. L. solanacearum’ (CLso). All Liberibacters encode a completely conserved gene repertoire for both flagella and Tad (Tight Adherence) pili and all are missing genes critical for nucleotide biosynthesis. Both flagellar swimming and Tad pilus-mediated twitching motility in Lcr were demonstrated for the first time. A role for Tad pili in the uptake of extracellular dsDNA for food in Liberibacters was suspected because both twitching and DNA uptake are impossible without repetitive pilus extension and retraction, and no genes encoding other pilus assemblages or mechanisms for DNA uptake were predicted to be even partially present in any of the 35 fully sequenced Liberibacter genomes. Insertional mutations of the Lcr Tad pilus genes cpaA, cpaB, cpaE, cpaF and tadC all displayed such severely reduced growth and viability that none could be complemented. A mutation affecting cpaF (motor ATPase) was further characterized and the strain displayed concomitant loss of twitching, viability and reduced periplasmic uptake of extracellular dsDNA. Mutations of comEC, encoding the inner membrane competence channel, had no effect on either motility or growth but completely abolished natural transformation in Lcr. The comEC mutation was restored by complementation using comEC from Lcr but not from CLas strain psy62 or CLso strain RS100, indicating that unlike Lcr, these pathogens were not naturally competent for transformation. This report provides the first evidence that the Liberibacter Tad pili are dynamic and essential for both motility and DNA uptake, thus extending their role beyond surface adherence.
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Affiliation(s)
- Lulu Cai
- Plant Pathology Department, University of Florida, Gainesville, Florida, United States of America
| | - Mukesh Jain
- Plant Pathology Department, University of Florida, Gainesville, Florida, United States of America
| | - Marta Sena-Vélez
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Kathryn M. Jones
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Laura A. Fleites
- USDA Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, New York, United States of America
| | - Michelle Heck
- USDA Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, New York, United States of America
| | - Dean W. Gabriel
- Plant Pathology Department, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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Jain M, Cai L, Fleites LA, Munoz-Bodnar A, Davis MJ, Gabriel DW. Liberibacter crescens Is a Cultured Surrogate for Functional Genomics of Uncultured Pathogenic ' Candidatus Liberibacter' spp. and Is Naturally Competent for Transformation. PHYTOPATHOLOGY 2019; 109:1811-1819. [PMID: 31090497 DOI: 10.1094/phyto-04-19-0129-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
'Candidatus Liberibacter' spp. are uncultured insect endosymbionts and phloem-limited bacterial plant pathogens associated with diseases ranging from severe to nearly asymptomatic. 'Ca. L. asiaticus', causal agent of Huanglongbing or citrus "greening," and 'Ca. L. solanacearum', causal agent of potato zebra chip disease, respectively threaten citrus and potato production worldwide. Research on both pathogens has been stymied by the inability to culture these agents and to reinoculate into any host. Only a single isolate of a single species of Liberibacter, Liberibacter crescens, has been axenically cultured. L. crescens strain BT-1 is genetically tractable to standard molecular manipulation techniques and has been developed as a surrogate model for functional studies of genes, regulatory elements, promoters, and secreted effectors derived from the uncultured pathogenic Liberibacters. Detailed, step-by-step, and highly reproducible protocols for axenic culture, transformation, and targeted gene knockouts of L. crescens are described. In the course of developing these protocols, we found that L. crescens is also naturally competent for direct uptake and homology-guided chromosomal integration of both linear and circular plasmid DNA. The efficiency of natural transformation was about an order of magnitude higher using circular plasmid DNA compared with linearized fragments. Natural transformation using a replicative plasmid was obtained at a rate of approximately 900 transformants per microgram of plasmid, whereas electroporation using the same plasmid resulted in 6 × 104 transformants. Homology-guided marker interruptions using either natural uptake or electroporation of nonreplicative plasmids yielded 10 to 12 transformation events per microgram of DNA, whereas similar interruptions using linear fragments via natural uptake yielded up to 34 transformation events per microgram of DNA.
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Affiliation(s)
- M Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - L Cai
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - L A Fleites
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - A Munoz-Bodnar
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - M J Davis
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
| | - D W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
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Jain M, Munoz-Bodnar A, Gabriel DW. Concomitant Loss of the Glyoxalase System and Glycolysis Makes the Uncultured Pathogen "Candidatus Liberibacter asiaticus" an Energy Scavenger. Appl Environ Microbiol 2017; 83:e01670-17. [PMID: 28939611 PMCID: PMC5691416 DOI: 10.1128/aem.01670-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/09/2017] [Indexed: 01/28/2023] Open
Abstract
Methylglyoxal (MG) is a cytotoxic, nonenzymatic by-product of glycolysis that readily glycates proteins and DNA, resulting in carbonyl stress. Glyoxalase I and II (GloA and GloB) sequentially convert MG into d-lactic acid using glutathione (GSH) as a cofactor. The glyoxalase system is essential for the mitigation of MG-induced carbonyl stress, preventing subsequent cell death, and recycling GSH for maintenance of cellular redox poise. All pathogenic liberibacters identified to date are uncultured, including "Candidatus Liberibacter asiaticus," a psyllid endosymbiont and causal agent of the severely damaging citrus disease "huanglongbing." In silico analysis revealed the absence of gloA in "Ca Liberibacter asiaticus" and all other pathogenic liberibacters. Both gloA and gloB are present in Liberibacter crescens, the only liberibacter that has been cultured. L. crescens GloA was functional in a heterologous host. Marker interruption of gloA in L. crescens appeared to be lethal. Key glycolytic enzymes were either missing or significantly downregulated in "Ca Liberibacter asiaticus" compared to (cultured) L. crescens Marker interruption of sut, a sucrose transporter gene in L. crescens, decreased its ability to take up exogenously supplied sucrose in culture. "Ca Liberibacter asiaticus" lacks a homologous sugar transporter but has a functional ATP/ADP translocase, enabling it to thrive both in psyllids and in the sugar-rich citrus phloem by (i) avoiding sucrose uptake, (ii) avoiding MG generation via glycolysis, and (iii) directly importing ATP from the host cell. MG detoxification enzymes appear to be predictive of "Candidatus" status for many uncultured pathogenic and environmental bacteria.IMPORTANCE Discovered more than 100 years ago, the glyoxalase system is thought to be present across all domains of life and fundamental to cellular growth and viability. The glyoxalase system protects against carbonyl stress caused by methylglyoxal (MG), a highly reactive, mutagenic and cytotoxic compound that is nonenzymatically formed as a by-product of glycolysis. The uncultured alphaproteobacterium "Ca Liberibacter asiaticus" is a well-adapted endosymbiont of the Asian citrus psyllid, which transmits the severely damaging citrus disease "huanglongbing." "Ca Liberibacter asiaticus" lacks a functional glyoxalase pathway. We report here that the bacterium is able to thrive both in psyllids and in the sugar-rich citrus phloem by (i) avoiding sucrose uptake, (ii) avoiding (significant) MG generation via glycolysis, and (iii) directly importing ATP from the host cell. We hypothesize that failure to culture "Ca Liberibacter asiaticus" is at least partly due to its dependence on host cells for both ATP and MG detoxification.
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Affiliation(s)
- Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | | | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
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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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Jain M, Fleites LA, Gabriel DW. Prophage-Encoded Peroxidase in 'Candidatus Liberibacter asiaticus' Is a Secreted Effector That Suppresses Plant Defenses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:1330-7. [PMID: 26313412 DOI: 10.1094/mpmi-07-15-0145-r] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
'Candidatus Liberibacter asiaticus' is transmitted by psyllids and causes huanglongbing (HLB), a lethal disease of citrus. Most pathogenic 'Ca. L. asiaticus' strains carry two nearly identical prophages similar to SC1 and SC2 in strain UF506. SC2 was observed to replicate as a moderately high-copy excision plasmid encoding a reactive oxygen species-scavenging peroxidase (SC2_gp095), a predicted lysogenic conversion factor. SC2_gp095 was expressed at significantly higher levels in periwinkle than in citrus and was suppressed in psyllids. SC2_gp095 was cloned in a shuttle vector and transformed into Escherichia coli and Liberibacter crescens, a culturable proxy for 'Ca. L. asiaticus'. Transformed L. crescens cells showed 20 to 25% enhanced resistance to H₂O₂on agar plates, 47% greater enzymatic activity, and enhanced growth in liquid cultures. A nonclassical secretion potential was predicted for SC2_gp095 and secretion from L. crescens was confirmed by enzymatic and Western blot analyses. Transient expression of SC2_gp095 in planta resulted in strong transcriptional downregulation of RbohB, the key gatekeeper of the H₂O₂-mediated defense signaling in plants, helping explain the surprisingly long incubation period (years) before HLB symptoms appear in 'Ca. L. asiaticus'-infected citrus. 'Ca. L. asiaticus' peroxidase is likely a secreted, horizontally acquired effector that suppresses host symptom development, a tactic used by most biotrophic plant pathogens.
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Affiliation(s)
- Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611-0680, U.S.A
| | - Laura A Fleites
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611-0680, U.S.A
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611-0680, U.S.A
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Fleites LA, Jain M, Zhang S, Gabriel DW. "Candidatus Liberibacter asiaticus" prophage late genes may limit host range and culturability. Appl Environ Microbiol 2014; 80:6023-30. [PMID: 25063651 PMCID: PMC4178692 DOI: 10.1128/aem.01958-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 07/17/2014] [Indexed: 01/28/2023] Open
Abstract
"Candidatus Liberibacter asiaticus" is an uncultured alphaproteobacterium that systemically colonizes its insect host both inter- and intracellularly and also causes a severe, crop-destroying disease of citrus called huanglongbing, or citrus "greening." In planta, "Ca. Liberibacter asiaticus" is also systemic but phloem limited. "Ca. Liberibacter asiaticus" strain UF506 carries two predicted prophages, SC1 and SC2. Bacteriophage particles have been observed in experimentally "Ca. Liberibacter asiaticus"-infected periwinkle but not in any other host. Comparative gene expression analysis of predicted SC1 late genes showed a much higher level of late gene expression, including holin transcripts (SC1_gp110), in "Ca. Liberibacter asiaticus"-infected periwinkle relative to "Ca. Liberibacter asiaticus"-infected citrus. To functionally characterize predicted holin and endolysin activity, SC1_gp110 and two predicted endolysins, one within SC1 (SC1_gp035) and another well outside the predicted prophage region (CLIBASIA_04790), were cloned and expressed in Escherichia coli. Both SC1 genes inhibited bacterial growth consistent with holin and endolysin function. The holin (SC1_gp110) promoter region was fused with a uidA reporter on pUFR071, a wide bacterial host range (repW) replicon, and used to transform Liberibacter crescens strain BT-1 by electroporation. BT-1 is the only liberibacter strain cultured to date and was used as a proxy for "Ca. Liberibacter asiaticus." pUFR071 was >95% stable without selection in BT-1 for over 20 generations. The reporter construct exhibited strong constitutive glucuronidase (GUS) activity in culture-grown BT-1 cells. However, GUS reporter activity in BT-1 was suppressed in a dose-dependent manner by crude aqueous extracts from psyllids. Taken together with plant expression data, these observations indicate that "Ca. Liberibacter asiaticus" prophage activation may limit "Ca. Liberibacter asiaticus" host range and culturability.
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Affiliation(s)
- Laura A Fleites
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Shujian Zhang
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, Florida, USA
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Rott P, Fleites LA, Mensi I, Sheppard L, Daugrois JH, Dow JM, Gabriel DW. The RpfCG two-component system negatively regulates the colonization of sugar cane stalks by Xanthomonas albilineans. MICROBIOLOGY-SGM 2013; 159:1149-1159. [PMID: 23538716 DOI: 10.1099/mic.0.065748-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The genome of Xanthomonas albilineans, the causal agent of sugar cane leaf scald, carries a gene cluster encoding a predicted quorum sensing system that is highly related to the diffusible signalling factor (DSF) systems of the plant pathogens Xylella fastidiosa and Xanthomonas campestris. In these latter pathogens, a cluster of regulation of pathogenicity factors (rpf) genes encodes the DSF system and is involved in control of various cellular processes. Mutation of Xanthomonas albilineans rpfF, encoding a predicted DSF synthase, in Florida strain XaFL07-1 resulted in a small reduction of disease severity (DS). Single-knockout mutations of rpfC and rpfG (encoding a predicted DSF sensor and regulator, respectively) had no effect on DS or swimming motility of the pathogen. However, capacity of the pathogen to cause disease was slightly reduced and swimming motility was severely affected when rpfG and rpfC were both deleted. Similar results were obtained when the entire rpfGCF region was deleted. Surprisingly, when the pathogen was mutated in rpfG or rpfC (single or double mutations) it was able to colonize sugar cane spatially more efficiently than the wild-type. Mutation in rpfF alone did not affect the degree of spatial invasion. We conclude that the DSF signal contributes to symptom expression but not to invasion of sugar cane stalks by Xanthomonas albilineans strain XaFL07-1, which is mainly controlled by the RpfCG two-component system.
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Affiliation(s)
- Philippe Rott
- University of Florida, Department of Plant Pathology, Gainesville 32611, Florida, USA
- CIRAD, UMR BGPI, F-34398 Montpellier, France
| | - Laura A Fleites
- University of Florida, Department of Plant Pathology, Gainesville 32611, Florida, USA
| | - Imène Mensi
- CIRAD, UMR BGPI, F-34398 Montpellier, France
| | | | | | - J Maxwell Dow
- Department of Microbiology, Biosciences Institute, University College Cork, Cork, Ireland
| | - Dean W Gabriel
- University of Florida, Department of Plant Pathology, Gainesville 32611, Florida, USA
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Tanaka M, Wali UM, Nakayashiki H, Fukuda T, Mizumoto H, Ohnishi K, Kiba A, Hikichi Y. Implication of an Aldehyde Dehydrogenase Gene and a Phosphinothricin N-Acetyltransferase Gene in the Diversity of Pseudomonas cichorii Virulence. Genes (Basel) 2011; 3:62-80. [PMID: 24704843 PMCID: PMC3899961 DOI: 10.3390/genes3010062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 10/28/2011] [Accepted: 11/07/2011] [Indexed: 01/14/2023] Open
Abstract
Pseudomonas cichorii harbors the hrp genes. hrp-mutants lose their virulence on eggplant but not on lettuce. A phosphinothricin N-acetyltransferase gene (pat) is located between hrpL and an aldehyde dehydrogenase gene (aldH) in the genome of P. cichorii. Comparison of nucleotide sequences and composition of the genes among pseudomonads suggests a common ancestor of hrp and pat between P. cichorii strains and P. viridiflava strains harboring the single hrp pathogenicity island. In contrast, phylogenetic diversification of aldH corresponded to species diversification amongst pseudomonads. In this study, the involvement of aldH and pat in P. cichorii virulence was analyzed. An aldH-deleted mutant (ΔaldH) and a pat-deleted mutant (Δpat) lost their virulence on eggplant but not on lettuce. P. cichorii expressed both genes in eggplant leaves, independent of HrpL, the transcriptional activator for the hrp. Inoculation into Asteraceae species susceptible to P. cichorii showed that the involvement of hrp, pat and aldH in P. cichorii virulence is independent of each other and has no relationship with the phylogeny of Asteraceae species based on the nucleotide sequences of ndhF and rbcL. It is thus thought that not only the hrp genes but also pat and aldH are implicated in the diversity of P. cichorii virulence on susceptible host plant species.
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Affiliation(s)
- Masayuki Tanaka
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan.
| | - Ullah Md Wali
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan.
| | - Hitoshi Nakayashiki
- Laboratory of Plant Pathology, Kobe University, Kobe, Hyogo 657-8501, Japan.
| | - Tatsuya Fukuda
- Faculty of Agriculture, Kochi University, Nankoku 783-8502, Japan.
| | - Hiroyuki Mizumoto
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan.
| | - Kouhei Ohnishi
- Research Institute of Molecular Genetics, Kochi University, Nankoku, Kochi 783-8502, Japan.
| | - Akinori Kiba
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan.
| | - Yasufumi Hikichi
- Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan.
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Johnson KL, Minsavage GV, Le T, Jones JB, Walcott RR. Efficacy of a Nonpathogenic Acidovorax citrulli Strain as a Biocontrol Seed Treatment for Bacterial Fruit Blotch of Cucurbits. PLANT DISEASE 2011; 95:697-704. [PMID: 30731899 DOI: 10.1094/pdis-09-10-0660] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Bacterial fruit blotch (BFB), caused by the seedborne, gram-negative bacterium Acidovorax citrulli, is a serious threat to cucurbit seed and fruit production worldwide. Because of the lack of effective management strategies, we investigated the efficacy of a nonpathogenic A. citrulli strain as a biological control seed treatment for BFB. For this study, we generated a type III secretion system mutant of A. citrulli, AAC00-1ΔhrcC, that was nonpathogenic on watermelon but retained its ability to colonize germinating watermelon seed. With watermelon seed naturally infested with A. citrulli, AAC00-1ΔhrcC reduced BFB seedling transmission by 81.8% relative to control seed. In comparison, another A. citrulli antagonist, A. avenae strain AAA 99-2, reduced BFB seedling transmission by 74.6% for seed samples from the same lot. Additionally, when female watermelon blossoms were protected with AAC00-ΔhrcC and subsequently challenged with AAC00-1, the resulting seedlots displayed 8% BFB seedling transmission. This was not significantly different than seed from blossoms protected with AAA 99-2 (4%) but significantly less than those from blossoms protected with 0.1 M phosphate-buffered saline (36%). These results suggest that nonpathogenic A. citrulli has potential as a biological control seed treatment component in a comprehensive BFB management program.
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Affiliation(s)
- K L Johnson
- Department of Plant Pathology, University of Georgia, Athens 30602
| | - G V Minsavage
- Department of Plant Pathology, University of Florida, Gainesville 32611
| | - T Le
- Department of Plant Pathology, University of Georgia
| | - J B Jones
- Department of Plant Pathology, University of Florida
| | - R R Walcott
- Department of Plant Pathology, University of Georgia
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12
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Matsumoto A, Igo MM. Species-specific type II restriction-modification system of Xylella fastidiosa temecula1. Appl Environ Microbiol 2010; 76:4092-5. [PMID: 20418439 PMCID: PMC2893502 DOI: 10.1128/aem.03034-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 04/19/2010] [Indexed: 11/20/2022] Open
Abstract
The transformation efficiency of Xylella fastidiosa can be increased by interfering with restriction by the strain-specific type II system encoded by the PD1607 and PD1608 genes. Here, we report results for two strategies: in vitro methylation using M.SssI and isolation of DNA from an Escherichia coli strain expressing the methylase PD1607.
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Affiliation(s)
- Ayumi Matsumoto
- Department of Microbiology, University of California, Davis, One Shields Avenue, Davis, California 95616
| | - Michele M. Igo
- Department of Microbiology, University of California, Davis, One Shields Avenue, Davis, California 95616
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13
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Vivien E, Pitorre D, Cociancich S, Pieretti I, Gabriel DW, Rott PC, Royer M. Heterologous production of albicidin: a promising approach to overproducing and characterizing this potent inhibitor of DNA gyrase. Antimicrob Agents Chemother 2007; 51:1549-52. [PMID: 17220426 PMCID: PMC1855474 DOI: 10.1128/aac.01450-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phytotoxin and polyketide antibiotic albicidin produced by Xanthomonas albilineans is a highly potent DNA gyrase inhibitor. Low yields of albicidin production have slowed studies of its chemical structure. Heterologous expression of albicidin biosynthetic genes in X. axonopodis pv. vesicatoria resulted in a sixfold increase in albicidin production, offering promising strategies for engineering overproduction.
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Affiliation(s)
- Eric Vivien
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR Agro.M-Cirad-Inra BGPI, Campus International de Baillarguet, TA 41/K, 34398 Montpellier Cedex 5, France
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14
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Oshiro EE, Nepomuceno RSL, Faria JB, Ferreira LCS, Ferreira RCC. Site-directed gene replacement of the phytopathogen Xanthomonas axonopodis pv. citri. J Microbiol Methods 2005; 65:171-9. [PMID: 16087261 DOI: 10.1016/j.mimet.2005.07.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Revised: 06/23/2005] [Accepted: 07/05/2005] [Indexed: 11/17/2022]
Abstract
In this work we defined experimental conditions for site-directed gene replacement of the Xanthomonas axonopodis pv. citri (Xac), an economically relevant pathogen of citrus plants. The procedure involved, first, optimizing the electrotransformation conditions of the Xac 306 strain and, second, constructing non-replicative suicide vectors carrying knockout copies of the target gene. Using specific experimental conditions, transformation efficiencies of Xac were at least 100 fold higher than those achieved with electroporation protocols previously designed for X. campestris transformation. Successful gene replacement events were achieved with a suicide vector derived from R6K plasmid (pWR-SS) but not with those with ColE1 replication origin. We have chosen the oppA as a target gene, encoding the binding component (OppA) of the major oligopeptide uptake system found in the genome of the Xac 306 strain, although not in X. campestris pv. campestris (Xcc). Defining the experimental conditions, which allow for the specific mutagenesis of the Xac 306 strain, represents a step in the understanding of both genetics and physiology of this economically important bacterial species.
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Affiliation(s)
- Elisa E Oshiro
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, SP, 05508-000, Brazil
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15
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Royer M, Costet L, Vivien E, Bes M, Cousin A, Damais A, Pieretti I, Savin A, Megessier S, Viard M, Frutos R, Gabriel DW, Rott PC. Albicidin pathotoxin produced by Xanthomonas albilineans is encoded by three large PKS and NRPS genes present in a gene cluster also containing several putative modifying, regulatory, and resistance genes. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2004; 17:414-427. [PMID: 15077674 DOI: 10.1094/mpmi.2004.17.4.414] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Xanthomonas albilineans, which causes leaf scald disease of sugarcane, produces a highly potent pathotoxin called albicidin. We report here sequencing and homology analysis of the major gene cluster, XALB1 (55,839 bp), and a second, smaller region, XALB2 (2,986 bp), involved in albicidin biosynthesis. XALB1 contains 20 open reading frames, including i) three large genes with a modular architecture characteristic of polyketide synthases (PKSs) and nonribosomal peptide synthases (NRPSs) and ii) several putative modifying, regulatory, and resistance genes. Sequencing and complementation studies of six albicidin-defective mutants enabled us to confirm the involvement of the three PKS and NRPS genes encoded by XALB1 in albicidin production. XALB2 contains only one gene that is required for post-translational activation of PKS and NRPS enzymes, confirming the involvement of these enzymes in albicidin biosynthesis. In silico analysis of these three PKS or NRPS enzymes allowed us to propose a model for the albicidin backbone assembly and to gain insight into the structural features of this pathotoxin. This is the first description of a complete mixed PKS-NRPS gene cluster for toxin production in the genus Xanthomonas.
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Affiliation(s)
- Monique Royer
- UMR 385 CIRAD/ENSAM/INRA Biologie et Génétique des Interactions Plante-Parasite, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Campus International de Baillarguet, TA 41/K, 34398 Montpellier Cedex 5, France
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16
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Tsuge S, Furutani A, Kubo Y, Horino O. Identification of a H+/glucose and galactose symporter gene glt from Xanthomonas oryzae pv. oryzae. Microbiol Immunol 2002; 45:543-7. [PMID: 11529561 DOI: 10.1111/j.1348-0421.2001.tb02656.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We identified a glucose and galactose transporter gene from the plant-pathogenic bacterium Xanthomonas oryzae pv. oryzae. Sequence analysis indicated that the gene, named glt, encoded a polypeptide of 592 amino acid residues and the product was significantly homologous with members of the Na+/glucose cotransporter (SGLT) family from mammalian and bacterial origin, especially with vSGLT from Vibrio parahaemolyticus (50% identity). GLT functioned as a glucose and galactose transporter in an Escherichia coli mutant deficient in glucose and galactose transport activity. A protonophore inhibited the transport activity, suggesting that GLT is a H+-coupled glucose/galactose symporter.
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Affiliation(s)
- S Tsuge
- Laboratory of Plant Pathology, Faculty of Agriculture, Kyoto Prefectural University, Kyoto, Japan.
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17
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Astua-Monge G, Minsavage GV, Stall RE, Davis MJ, Bonas U, Jones JB. Resistance of tomato and pepper to T3 strains of Xanthomonas campestris pv. vesicatoria is specified by a plant-inducible avirulence gene. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2000; 13:911-921. [PMID: 10975648 DOI: 10.1094/mpmi.2000.13.9.911] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Tomato race 3 (T3) of Xanthomonas campestris pv. vesicatoria (Xcv) elicits a hypersensitive response (HR) in leaves of Lycopersicon esculentum near-isogenic line (NIL) 216 and pepper genotypes. One cosmid clone (35 kb) selected from a genomic library of a T3 strain induced an HR in all resistant plants. A 1.5-kb active subclone containing the putative avirulence (avr) gene, designated avrXv3, was sequenced. The avrXv3 gene encodes a 654-bp open reading frame (ORF) with no homology to any known gene. Expression studies with a fusion of this gene and uidA indicated that avrXv3 is plant inducible and controlled by the hypersensitivity and pathogenicity (hrp) regulatory system. Mutational analysis and transcription activation assays revealed that AvrXv3 has transcription activation activity in yeast, and that the putative domain responsible for that activity is located at the C terminus of the AvrXv3 protein. Agrobacterium tumefaciens-mediated transient expression confirmed the direct role of AvrXv3 in eliciting the HR in tomato NIL 216 and supported the hypothesis that Avr proteins must be present inside the plant host cell to trigger the HR.
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Affiliation(s)
- G Astua-Monge
- Department of Plant Pathology, University of Florida, Gainesville 32611, USA
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18
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Lewis TA, Cortese MS, Sebat JL, Green TL, Lee CH, Crawford RL. A Pseudomonas stutzeri gene cluster encoding the biosynthesis of the CCl4-dechlorination agent pyridine-2,6-bis(thiocarboxylic acid). Environ Microbiol 2000; 2:407-16. [PMID: 11234929 DOI: 10.1046/j.1462-2920.2000.00122.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A spontaneous mutant of Pseudomonas stutzeri strain KC lacked the carbon tetrachloride (CCl4) transformation ability of wild-type KC. Analysis of restriction digests separated by pulsed-field gel electrophoresis (PFGE) indicated that the mutant strain CTN1 differed from strain KC by deletion of approximately 170 kb of chromosomal DNA. CTN1 did not produce pyridine-2,6-bis(thiocarboxylic acid) (PDTC), the agent determined to be responsible for CCl4 dechlorination in cultures of strain KC. Cosmids from a genomic library of strain KC containing DNA from within the deleted region were identified by hybridization with a 148 kb genomic Spel fragment absent in strain CTN1. Several cosmids identified in this manner were further screened for complementation of the PDTC biosynthesis-negative (Pdt -) phenotype. One cosmid (pT31) complemented the Pdt- phenotype of CTN1 and conferred CCl4 transformation activity and PDTC production upon other pseudomonads. Southern analysis showed that none of three other P. stutzeri strains representing three genomovars contained DNA that would hybridize with the 25,746 bp insert of pT31. Transposon mutagenesis of pT31 identified open reading frames (ORFs) whose disruption affected the ability to make PDTC in the strain CTN1 background. These data describe the pdt locus of strain KC as residing in a non-essential region of the chromosome subject to spontaneous deletion. The pdt locus is necessary for PDTC biosynthesis in strain KC and is sufficient for PDTC biosynthesis by other pseudomonads but is not a common feature of P. stutzeri strains.
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Affiliation(s)
- T A Lewis
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington 05405, USA.
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19
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Ciesiolka LD, Hwin T, Gearlds JD, Minsavage GV, Saenz R, Bravo M, Handley V, Conover SM, Zhang H, Caporgno J, Phengrasamy NB, Toms AO, Stall RE, Whalen MC. Regulation of expression of avirulence gene avrRxv and identification of a family of host interaction factors by sequence analysis of avrBsT. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 1999; 12:35-44. [PMID: 9885191 DOI: 10.1094/mpmi.1999.12.1.35] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Resistance in tomato line Hawaii 7998 as well as in several nonhost plants to Xanthomonas campestris pv. vesicatoria tomato strain (XcvT) is mediated in part by the avirulence gene avrRxv. Analysis of growth of wild-type and avrRxv deletion strains indicates that avrRxv plays a crucial role in the ability of XcvT 92-14 to induce resistance on Hawaii 7998. We used avrRxv reporter gene fusions and Northern (RNA) blot analysis to test several growth environments for inductive potential. We found that avrRxv is constitutively expressed at high levels and that growth in planta, in tobacco conditioned medium, and in hrp-inductive medium XVM2 did not affect the high levels of expression. In addition, hrp structural and regulatory mutant backgrounds had no effect. We mutated the bipartite plant inducible promoter (PIP)-box sequence and found that avrRxv activity appears to be independent of an intact PIP-box element. We present the sequence of the avrRxv homologue called avrBsT and align the six AvrRxv host interaction factor family members including mammalian pathogen virulence factors YopJ and YopP from Yersinia spp. and AvrA from Salmonella typhimurium, and open reading frame Y4LO with unknown function from the symbiont Rhizobium sp.
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Affiliation(s)
- L D Ciesiolka
- Department of Biology, San Francisco State University, CA 94132, USA
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20
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Chakrabarty PK, Duan YP, Gabriel DW. Cloning and Characterization of a Member of the Xanthomonas avr/pth Gene Family That Evades All Commercially Utilized Cotton R Genes in the United States. PHYTOPATHOLOGY 1997; 87:1160-1167. [PMID: 18945013 DOI: 10.1094/phyto.1997.87.11.1160] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ABSTRACT The highly virulent African strains of Xanthomonas campestris pv. malvacearum are quarantined pathogens in the United States and can evade or overcome all commercially utilized resistance (R) genes in cotton grown in the United States including the entire set of host differential lines used to distinguish 19 races of the pathogen. Nevertheless, the African strains carry multiple DNA fragments that strongly hybridize with members of the Xanthomonas avirulence (avr)/pathogenicity (pth) gene family. Since all previously tested members of the gene family confer avirulence against one or more R genes in cotton, strains carrying multiple members might not be expected to evade so many different R genes. The hybridizing DNA fragments were cloned from African strain XcmN and found to confer water-soaking ability to a nearly asymptomatic mutant strain of the pathogen. Restriction mapping, Southern hybridization, and DNA sequencing of the cloned fragments from XcmN were used to identify two water-soaking genes, pthN and pthN2, as new members of the Xanthomonas avr/pth gene family. The complete DNA sequence of pthN was obtained, and it is >94% identical with all other sequenced members of the gene family. Gene fusions of pthN with avrb6 (another family member) and other experiments revealed that the ability of African strain XcmN to water-soak cotton and avoid recognition by commercially used cotton R genes is determined by the specific repeats of multiple functional members of the Xanthomonas avr/pth gene family.
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21
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Elhai J, Vepritskiy A, Muro-Pastor AM, Flores E, Wolk CP. Reduction of conjugal transfer efficiency by three restriction activities of Anabaena sp. strain PCC 7120. J Bacteriol 1997; 179:1998-2005. [PMID: 9068647 PMCID: PMC178925 DOI: 10.1128/jb.179.6.1998-2005.1997] [Citation(s) in RCA: 252] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The efficiency of conjugal transfer of plasmids from Escherichia coli to the cyanobacterium Anabaena sp. strain PCC 7120 was quantitated as a function of the number of restriction sites for the restriction enzymes carried by the recipient. In addition to the previously recognized isoschizomers of AvaI and AvaII, PCC 7120 was found to possess an isoschizomer of AvaIII. Plasmids modified in E. coli with methylases that protect in vitro against restriction by the three enzymes were transferred with high efficiency, nearly independent of the number of restriction sites on the plasmid. Plasmids left unprotected against one of the three restriction enzymes were transferred with lower efficiencies. For low numbers of sites, the efficiency of conjugal transfer decreased as an exponential function of the number of unprotected sites. The methods presented may be used to increase the efficiency of conjugal transfer into restriction-competent bacteria.
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Affiliation(s)
- J Elhai
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing 48824-1312, USA
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22
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Rott PC, Costet L, Davis MJ, Frutos R, Gabriel DW. At least two separate gene clusters are involved in albicidin production by Xanthomonas albilineans. J Bacteriol 1996; 178:4590-6. [PMID: 8755889 PMCID: PMC178228 DOI: 10.1128/jb.178.15.4590-4596.1996] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Transposon mutagenesis was used to obtain mutations affecting production of the toxin albicidin in Xanthomonas albilineans, which causes leaf scald disease of sugarcane and is also pathogenic to corn. Transposon Tn5-gusA inserted randomly into genomic DNA of X. albilineans Xa23R1 at a frequency of 10(-4) to 10(-5) per recipient after conjugal transfer from Escherichia coli. Fifty prototrophic mutants defective in albicidin production were isolated from 7,100 Tn5-gusA insertional derivatives tested for toxin production by an antibiosis bioassay. EcoRI fragments containing Tn5 flanking sequences from two mutants (AM15 and AM40) were cloned and used to probe a wild-type Xa23R1 DNA library by colony hybridization. Nine cosmids showed homology to the AM15 probe, and six showed homology to the AM40 probe. Four cosmid clones hybridized to both probes. Forty-five of the 50 defective mutants were restored to albicidin production with two overlapping cosmid clones. Restriction mapping showed that these mutants span a genomic region of about 48 kb. At least one other gene cluster is also involved in albicidin production in Xa23R1. DNA fragments from the 48-kb cluster proved to be very specific to X. albilineans. Some mutants affected in albicidin production retain their ability to colonize sugarcane cultivated in vitro.
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Affiliation(s)
- P C Rott
- Department of Plant Pathology, University of Florida, Gainesville, Florida 32611, USA
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23
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Yang Y, Gabriel DW. Intragenic recombination of a single plant pathogen gene provides a mechanism for the evolution of new host specificities. J Bacteriol 1995; 177:4963-8. [PMID: 7665472 PMCID: PMC177271 DOI: 10.1128/jb.177.17.4963-4968.1995] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Gene pthA is required for virulence of Xanthomonas citri on citrus plants and has pleiotropic pathogenicity and avirulence functions when transferred to many different xanthomonads. DNA sequencing revealed that pthA belongs to a family of Xanthomonas avirulence/pathogenicity genes characterized by nearly identical 102-bp tandem repeats in the central region. By inserting an nptI-sac cartridge into the tandemly repeated region of pthA as a selective marker, intragenic recombination among homologous repeats was observed in both Xanthomonas spp. and Escherichia coli. Intragenic recombination within pthA created new genes with novel host specificities and altered pathogenicity and/or avirulence phenotypes. Many pthA recombinants gained or lost avirulence function in pathogenicity assays on bean, citrus, and cotton cultivars. Although the ability to induce cell division (hyperplastic cankers) on citrus could be lost, this ability was not acquired on cotton or bean plants. Intragenic recombination therefore provides a genetic mechanism for the generation of multiple, different, and gratuitous avirulence genes from a single, required, host-specific pathogenicity gene.
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Affiliation(s)
- Y Yang
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville 32611, USA
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24
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Rabibhadana S, Chamnongpol S, Trempy JE, Ambulos NP, Mongkolsuk S. Isolation and expression in Escherichia coli of a Xanthomonas oryzae recA-like gene. Gene 1993; 132:113-8. [PMID: 8406033 DOI: 10.1016/0378-1119(93)90522-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The recA gene from the bacterium Xanthomonas oryzae pv. oryzae (Xoo), a rice pathogen, was cloned based on its ability to complement DNA repair defects of Escherichia coli recA- mutants. The Xoo recA was localized to a 1.3-kb Sau3AI-XhoI fragment and, when cloned into pBR322, specifies increased methylmethanesulfonate and mitomycin C resistance to E. coli recA mutants and allows lambda red- gam- to plaque on an E. coli recA- host. An E. coli recA- strain harboring a plasmid containing the Xoo recA-like gene was shown to produce a 40-kDa protein which cross-reacted with an anti-E. coli RecA antibody. A similar molecular mass protein to RecA has been detected in several Xanthomonas pathovars using an anti-E. coli RecA antibody. Furthermore, the cloned Xoo recA was shown to hybridize to genomic DNA from various Xanthomonas pathovars, but not to genomic DNA from other bacteria species under high-stringency hybridization conditions. These results indicate the isolation of the Xoo recA gene.
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Affiliation(s)
- S Rabibhadana
- Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand
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25
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Kingsley MT, Gabriel DW, Marlow GC, Roberts PD. The opsX locus of Xanthomonas campestris affects host range and biosynthesis of lipopolysaccharide and extracellular polysaccharide. J Bacteriol 1993; 175:5839-50. [PMID: 8376331 PMCID: PMC206663 DOI: 10.1128/jb.175.18.5839-5850.1993] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Xanthomonas campestris pv. citrumelo strain 3048 is the causal agent of citrus bacterial leaf spot disease and has a wide host range that includes rutaceous and leguminous plants. A spontaneous prototrophic mutant of strain 3048 (strain M28) that had lost virulence on citrus but retained virulence on bean plants was recovered. Growth studies in planta showed that M28 cells died rapidly in citrus leaves but grew normally in bean leaves. In addition to the loss of citrus-specific virulence, M28 displayed the following mutant phenotypes in culture: decreased growth rate, reduction of the amount of exopolysaccharide (to ca. 25% of the amount in 3048), loss of capsules, and significant alterations of the two 3048 lipopolysaccharide (LPS) bands visualized by silver stain on polyacrylamide gels, consistent with a defect(s) in LPS assembly. A 38-kb DNA fragment from a 3048 total DNA library that complemented the mutant phenotypes of M28 was identified. The 38-kb fragment did not hybridize to two similarly sized fragments carrying different hrp (hypersensitive response and pathogenicity) genes cloned from 3048. Subcloning, DNA sequence analyses, and gene disruption experiments were used to identify a single gene, opsX (for outer-membrane polysaccharide), responsible for the mutant phenotypes of M28. At least one other gene downstream from opsX also affected the same phenotypes and may be part of a gene cluster. We report here the DNA sequence and transcriptional start site of opsX. A search of protein sequence data bases with the predicted 31.3-kDa OpsX sequence found strong similarity to Lsi-1 of Neisseria gonorrhoeae and RfaQ of Escherichia coli (both are involved in LPS core assembly). The host-specific virulence function of opsX appears to involve biosynthesis of the extracellular polysaccharide and a complete LPS. Both may be needed in normal amounts for protection from citrus, but not bean, defense compounds.
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Affiliation(s)
- M T Kingsley
- Plant Pathology Department, University of Florida, Gainesville 32611-0680
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26
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Mermelstein LD, Papoutsakis ET. In vivo methylation in Escherichia coli by the Bacillus subtilis phage phi 3T I methyltransferase to protect plasmids from restriction upon transformation of Clostridium acetobutylicum ATCC 824. Appl Environ Microbiol 1993; 59:1077-81. [PMID: 8386500 PMCID: PMC202241 DOI: 10.1128/aem.59.4.1077-1081.1993] [Citation(s) in RCA: 221] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The restriction endonuclease Cac824I has been shown to be a major barrier to electrotransformation of Clostridium acetobutylicum ATCC 824 (L. D. Mermelstein, N. E. Welker, G. N. Bennett, and E. T. Papoutsakis, Bio/Technology 10:190-195, 1992). Methylation by the phi 3T I methyltransferase encoded by Bacillus subtilis phage phi 3T was shown to protect plasmid DNA from restriction by Cac824I. Expression in Escherichia coli of the phi 3tI gene (which encodes the phi 3T I methyltransferase) from pAN1, which replicates via the p15A origin of replication, was sufficient to completely methylate coresident E. coli-C. acetobutylicum shuttle vectors with ColE1 origins of replication. Three shuttle vectors (pIMP1, pSYL2, and pSYL7) methylated in this manner were used to efficiently electrotransform strain ATCC 824. These vectors could not be introduced into strain ATCC 824 when unmethylated because the E. coli portions of the plasmids contain a large number of Cac824I sites. This method obviates the need to use B. subtilis-C. acetobutylicum shuttle vectors with few Cac824I sites to introduce DNA into C. acetobutylicum ATCC 824.
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Affiliation(s)
- L D Mermelstein
- Department of Chemical Engineering, Northwestern University, Evanston, Illinois 60208
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Withers BE, Ambroso LA, Dunbar JC. Structure and evolution of the XcyI restriction-modification system. Nucleic Acids Res 1992; 20:6267-73. [PMID: 1475187 PMCID: PMC334515 DOI: 10.1093/nar/20.23.6267] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The XcyI restriction-modification system from Xanthomonas cyanopsidis recognizes the sequence, CCCGGG. The XcyI endonuclease and methylase genes have been cloned and sequenced and were found to be aligned in a head to tail orientation with the methylase preceding and overlapping the endonuclease by one base pair. The nucleotide sequence codes for an N4 cytosine methyltransferase with a predicted molecular weight of 33,500 and an endonuclease comprised of 333 codons and a molecular weight of 36,600. Sequence comparisons revealed significant similarity between the XcyI, CfrI and SmaI methylisomers. In contrast, no similarity was detected between the primary structures of the XcyI and SmaI endonucleases. The XcyI restriction-modification system is highly homologous to the XmaI genes, although the DNA sequences flanking the genes rapidly diverge. The sequence of the XcyI endonuclease contains two motifs which have recently been identified as essential to the activity of the EcoRV endonuclease.
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Affiliation(s)
- B E Withers
- Wayne State University School of Medicine, Detroit, MI 48201
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