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Sun X, Xiao F, Su Y, Li Z, Yu X, Parales RE, Li L. Cyclic di-GMP incorporates the transcriptional factor FleQ03 in Pseudomonas syringae MB03 to elicit biofilm-dependent resistance in response to Caenorhabditis elegans predation. J Invertebr Pathol 2024; 207:108189. [PMID: 39251105 DOI: 10.1016/j.jip.2024.108189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 08/24/2024] [Accepted: 09/03/2024] [Indexed: 09/11/2024]
Abstract
Bacteria usually form biofilms as a defense mechanism against predation by bacterivorous nematodes. In this context, the second messenger c-di-GMP from the wild-type Pseudomonas syringae MB03 actuates the transcriptional factor FleQ03 to elicit biofilm-dependent nematicidal activity against Caenorhabditis elegans N2. P. syringae MB03 cells exhibited nematicidal activity and c-di-GMP content in P. syringae MB03 cells was increased after feeding to nematodes. Expression of a diguanylate cyclase (DGC) gene in P. syringae MB03 resulted in an increased c-di-GMP content, biofilm yield and nematicidal activity, whereas converse effects were obtained when expressing a phosphodiesterase (PDE) gene. Molecular docking and isothermal titration calorimetry assays verified the affinity activity between c-di-GMP and the FleQ03 protein. The disruption of the fleQ03 gene in P. syringae MB03, while increasing c-di-GMP content, significantly diminished both biofilm formation and nematicidal activity. Interestingly, P. syringae MB03 formed a full-body biofilm around the worms against predation, probably extending from the tail to the head, whereas it was not observed in the fleQ03 gene disrupted cells. Thus, we hypothesized that c-di-GMP incorporated FleQ03 to reinforce bacterial biofilm and biofilm-dependent pathogenicity in response to C. elegans predation, providing insights into a possible means of resisting bacterivorous nematodes by bacteria in natural ecosystems.
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Affiliation(s)
- Xiaowen Sun
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; School of Life Sciences, Jianghan University, Wuhan 430056, China
| | - Fan Xiao
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yuwei Su
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhi Li
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xun Yu
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Rebecca E Parales
- Department of Microbiology and Molecular Genetics, College of Biological Sciences, University of California, Davis, USA.
| | - Lin Li
- National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
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Stevens DM, Moreno-Pérez A, Weisberg AJ, Ramsing C, Fliegmann J, Zhang N, Madrigal M, Martin G, Steinbrenner A, Felix G, Coaker G. Natural variation of immune epitopes reveals intrabacterial antagonism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.21.558511. [PMID: 37790530 PMCID: PMC10543004 DOI: 10.1101/2023.09.21.558511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Plants and animals detect biomolecules termed Microbe-Associated Molecular Patterns (MAMPs) and induce immunity. Agricultural production is severely impacted by pathogens which can be controlled by transferring immune receptors. However, most studies use a single MAMP epitope and the impact of diverse multi-copy MAMPs on immune induction is unknown. Here we characterized the epitope landscape from five proteinaceous MAMPs across 4,228 plant-associated bacterial genomes. Despite the diversity sampled, natural variation was constrained and experimentally testable. Immune perception in both Arabidopsis and tomato depended on both epitope sequence and copy number variation. For example, Elongation Factor Tu is predominantly single copy and 92% of its epitopes are immunogenic. Conversely, 99.9% of bacterial genomes contain multiple Cold Shock Proteins and 46% carry a non-immunogenic form. We uncovered a new mechanism for immune evasion, intrabacterial antagonism, where a non-immunogenic Cold Shock Protein blocks perception of immunogenic forms encoded in the same genome. These data will lay the foundation for immune receptor deployment and engineering based on natural variation.
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Affiliation(s)
- Danielle M. Stevens
- Integrative Genetics and Genomics Graduate Group, University of California, Davis, Davis CA 95616, USA
- Department of Plant Pathology, University of California, Davis, Davis CA 95616, USA
| | - Alba Moreno-Pérez
- Department of Plant Pathology, University of California, Davis, Davis CA 95616, USA
| | - Alexandra J. Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis OR, USA
| | - Charis Ramsing
- Department of Plant Pathology, University of California, Davis, Davis CA 95616, USA
| | - Judith Fliegmann
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72074 Tübingen, Germany
| | - Ning Zhang
- Boyce Thompson Institute for Plant Research, Ithaca NY, USA
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca NY, USA
| | - Melanie Madrigal
- Department of Plant Pathology, University of California, Davis, Davis CA 95616, USA
| | - Gregory Martin
- Boyce Thompson Institute for Plant Research, Ithaca NY, USA
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca NY, USA
| | - Adam Steinbrenner
- University of Washington, Department of Biology, Box 351800, Seattle, WA, 98195, USA
| | - Georg Felix
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, 72074 Tübingen, Germany
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, Davis CA 95616, USA
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3
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Liang X, Wei F, Yang H, Fan L, Cai X, Ma Y, Shi J, Xing K, Qiu L, Li X, Lu L, Ji J, Wen Y, Feng J. Flagella-Driven Motility Is Critical to the Virulence of Xanthomonas fragariae in Strawberry. PLANT DISEASE 2023; 107:3506-3516. [PMID: 37157097 DOI: 10.1094/pdis-03-23-0409-re] [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: 05/10/2023]
Abstract
Xanthomonas fragariae (X. fragariae) is the causal agent of angular leaf spots (ALS) in strawberry plants. Recently, a study in China isolated X. fragariae strain YL19, which was observed to cause both typical ALS symptoms and dry cavity rot in strawberry crown tissue; this was the first X. fragariae strain to have both these effects in strawberry. In this study, from 2020 to 2022, we isolated 39 X. fragariae strains from diseased strawberries in different production areas in China. Multilocus sequence typing (MLST) and phylogenetic analysis showed that X. fragariae strain YLX21 was genetically different from YL19 and other strains. Tests indicated that YLX21 and YL19 had different pathogenicities toward strawberry leaves and stem crowns. YLX21 did not cause ALS symptoms, rarely caused dry cavity rot in strawberry crown after wound inoculation, and never caused dry cavity rot after spray inoculation, but it did cause severe ALS symptoms after spray inoculation. However, YL19 caused more severe symptoms in strawberry crowns under both conditions. Moreover, YL19 had a single polar flagellum, while YLX21 had no flagellum. Motility and chemotaxis assays showed that YLX21 had weaker motility than YL19, which may explain why YLX21 tended to multiply in situ within the strawberry leaf rather than migrate to other tissues, causing more severe ALS symptoms and mild crown rot symptoms. Taken together, the new strain YLX21 helped us reveal critical factors underlying the pathogenicity of X. fragariae and the mechanism by which dry cavity rot in strawberry crowns forms.
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Affiliation(s)
- Xia Liang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Feng Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Hongliang Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Li Fan
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Xiaolin Cai
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Yangyang Ma
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Jiancheng Shi
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Kun Xing
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Lijuan Qiu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Xixuan Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Lijuan Lu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
| | - Jie Ji
- Institute of Plant Protection, Fujian Academy of Agriculture Sciences, Fuzhou 350013, Fujian, China
| | - Yingqiang Wen
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Jiayue Feng
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China
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Wang DJ, Shi JC, Fan L, Wang RJ, Wei F, Ma YY, Cai XL, Fan SH, Liang X, Yang HL, Xing K, Qiu LJ, Lu LJ, Li XX, Wen YQ, Feng JY. Systemic Colonization of Xanthomonas fragariae Strain YL19 Causing Dry Cavity Rot of Strawberry Crown Tissue in China. PLANT DISEASE 2023; 107:3542-3552. [PMID: 37194211 DOI: 10.1094/pdis-04-22-0783-re] [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: 05/18/2023]
Abstract
Xanthomonas fragariae usually causes angular leaf spot (ALS) of strawberry, a serious bacterial disease in many strawberry-producing regions worldwide. Recently, a new strain of X. fragariae (YL19) was isolated from strawberry in China and has been shown to cause dry cavity rot in strawberry crown. In this study, we constructed a green fluorescent protein (GFP)-labeled Xf YL19 (YL19-GFP) to visualize the infection process and pathogen colonization in strawberries. Foliar inoculation of YL19-GFP resulted in the pathogen migrating from the leaves to the crown, whereas dip inoculation of wounded crowns or roots resulted in the migration of bacteria from the crowns or roots to the leaves. These two invasion types both resulted in the systematic spread of YL19-GFP, but inoculation of a wounded crown was more harmful to the strawberry plant than foliar inoculation. Results increased our understanding of the systemic invasion of X. fragariae, and the resultant crown cavity caused by Xf YL19.
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Affiliation(s)
- Dan-Juan Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Jian-Cheng Shi
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Li Fan
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Ruo-Jing Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Feng Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Yang-Yang Ma
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Xiao-Lin Cai
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Si-Hao Fan
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Xia Liang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Hong-Liang Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Kun Xing
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Li-Juan Qiu
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Li-Juan Lu
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Xi-Xuan Li
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
| | - Ying-Qiang Wen
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Jia-Yue Feng
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
- Key Laboratory of Protected Horticulture Engineering in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China
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5
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McMullen JG, Lennon JT. Mark-recapture of microorganisms. Environ Microbiol 2023; 25:150-157. [PMID: 36310117 DOI: 10.1111/1462-2920.16267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 01/21/2023]
Affiliation(s)
| | - Jay T Lennon
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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6
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Baggs EL, Tiersma MB, Abramson BW, Michael TP, Krasileva KV. Characterization of defense responses against bacterial pathogens in duckweeds lacking EDS1. THE NEW PHYTOLOGIST 2022; 236:1838-1855. [PMID: 36052715 PMCID: PMC9828482 DOI: 10.1111/nph.18453] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/19/2022] [Indexed: 05/19/2023]
Abstract
ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) mediates the induction of defense responses against pathogens in most angiosperms. However, it has recently been shown that a few species have lost EDS1. It is unknown how defense against disease unfolds and evolves in the absence of EDS1. We utilize duckweeds; a collection of aquatic species that lack EDS1, to investigate this question. We established duckweed-Pseudomonas pathosystems and used growth curves and microscopy to characterize pathogen-induced responses. Through comparative genomics and transcriptomics, we show that the copy number of infection-associated genes and the infection-induced transcriptional responses of duckweeds differ from other model species. Pathogen defense in duckweeds has evolved along different trajectories than in other plants, including genomic and transcriptional reprogramming. Specifically, the miAMP1 domain-containing proteins, which are absent in Arabidopsis, showed pathogen responsive upregulation in duckweeds. Despite such divergence between Arabidopsis and duckweed species, we found conservation of upregulation of certain genes and the role of hormones in response to disease. Our work highlights the importance of expanding the pool of model species to study defense responses that have evolved in the plant kingdom independent of EDS1.
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Affiliation(s)
- Erin L. Baggs
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCA94720USA
| | - Meije B. Tiersma
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCA94720USA
| | - Brad W. Abramson
- Plant Molecular and Cellular Biology LaboratoryThe Salk Institute for Biological StudiesLa JollaCA92037USA
| | - Todd P. Michael
- Plant Molecular and Cellular Biology LaboratoryThe Salk Institute for Biological StudiesLa JollaCA92037USA
| | - Ksenia V. Krasileva
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCA94720USA
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7
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Laveilhé A, Fochesato S, Lalaouna D, Heulin T, Achouak W. Phytobeneficial traits of rhizobacteria under the control of multiple molecular dialogues. Microb Biotechnol 2022; 15:2083-2096. [PMID: 35502577 PMCID: PMC9249325 DOI: 10.1111/1751-7915.14023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 02/14/2022] [Accepted: 02/14/2022] [Indexed: 11/29/2022] Open
Abstract
Pseudomonads play crucial roles in plant growth promotion and control of plant diseases. However, under natural conditions, other microorganisms competing for the same nutrient resources in the rhizosphere may exert negative control over their phytobeneficial characteristics. We assessed the expression of phytobeneficial genes involved in biocontrol, biostimulation and iron regulation such as, phlD, hcnA, acdS, and iron‐small regulatory RNAs prrF1 and prrF2 in Pseudomonas brassicacearum co‐cultivated with three phytopathogenic fungi, and two rhizobacteria in the presence or absence of Brassica napus, and in relation to iron availability. We found that the antifungal activity of P. brassicacearum depends mostly on the production of DAPG and not on HCN whose production is suppressed by fungi. We have also shown that the two‐competing bacterial strains modulate the plant growth promotion activity of P. brassicacearum by modifying the expression of phlD, hcnA and acdS according to iron availability. Overall, it allows us to better understand the complexity of the multiple molecular dialogues that take place underground between microorganisms and between plants and its rhizosphere microbiota and to show that synergy in favour of phytobeneficial gene expression may exist between different bacterial species. We assessed the expression of phytobeneficial genes, phlD, hcnA and acdS, and iron‐small regulatory RNAs prrF1 and prrF2 in Pseudomonas brassicacearum co‐cultivated with three phytopathogenic fungi, and two rhizobacteria in the presence or absence of Brassica napus, and in relation to iron availability. Our study illustrates that interkingdom and interspecies interactions in addition to external factors may affect the success of introduced beneficial microorganisms by modulating the expression of phytobeneficial genes.
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Affiliation(s)
- Arnaud Laveilhé
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
| | - Sylvain Fochesato
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
| | - David Lalaouna
- ARN UPR 9002, Université de Strasbourg, CNRS, Strasbourg, F-67000, France
| | - Thierry Heulin
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
| | - Wafa Achouak
- Lab Microbial Ecology of the Rhizosphere (LEMiRE), CEA, CNRS, BIAM, Aix Marseille Univ, Saint-Paul-Lez-Durance, F-13108, France
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8
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Genome-Wide Transposon Screen of a Pseudomonas syringae mexB Mutant Reveals the Substrates of Efflux Transporters. mBio 2019; 10:mBio.02614-19. [PMID: 31662463 PMCID: PMC6819667 DOI: 10.1128/mbio.02614-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Bacteria express numerous efflux transporters that confer resistance to diverse toxicants present in their environment. Due to a high level of functional redundancy of these transporters, it is difficult to identify those that are of most importance in conferring resistance to specific compounds. The resistance-nodulation-division (RND) protein family is one such example of redundant transporters that are widespread among Gram-negative bacteria. Within this family, the MexAB-OprM protein complex is highly expressed and conserved among Pseudomonas species. We exposed barcoded transposon mutant libraries in isogenic wild-type and ΔmexB backgrounds in P. syringae B728a to diverse toxic compounds in vitro to identify mutants with increased susceptibility to these compounds. Mutants with mutations in genes encoding both known and novel redundant transporters but with partially overlapping substrate specificities were observed in a ΔmexB background. Psyr_0228, an uncharacterized member of the major facilitator superfamily of transporters, preferentially contributes to tolerance of acridine orange and acriflavine. Another transporter located in the inner membrane, Psyr_0541, contributes to tolerance of acriflavine and berberine. The presence of multiple redundant, genomically encoded efflux transporters appears to enable bacterial strains to tolerate a diversity of environmental toxins. This genome-wide screen performed in a hypersusceptible mutant strain revealed numerous transporters that would otherwise be dispensable under these conditions. Bacterial strains such as P. syringae that likely encounter diverse toxins in their environment, such as in association with many different plant species, probably benefit from possessing multiple redundant transporters that enable versatility with respect to toleration of novel toxicants.IMPORTANCE Bacteria use protein pumps to remove toxic compounds from the cell interior, enabling survival in diverse environments. These protein pumps can be highly redundant, making their targeted examination difficult. In this study, we exposed mutant populations of Pseudomonas syringae to diverse toxicants to identify pumps that contributed to survival in those conditions. In parallel, we examined pump redundancy by testing mutants of a population lacking the primary efflux transporter responsible for toxin tolerance. We identified partial substrate overlap for redundant transporters, as well as several pumps that appeared more substrate specific. For bacteria that are found in diverse environments, having multiple, partially redundant efflux pumps likely allows flexibility in habitat colonization.
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9
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Helmann TC, Ongsarte CL, Lam J, Deutschbauer AM, Lindow SE. Genome-Wide Transposon Screen of a Pseudomonas syringae mexB Mutant Reveals the Substrates of Efflux Transporters. mBio 2019. [PMID: 31662463 DOI: 10.1101/684605] [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] [Indexed: 05/12/2023] Open
Abstract
Bacteria express numerous efflux transporters that confer resistance to diverse toxicants present in their environment. Due to a high level of functional redundancy of these transporters, it is difficult to identify those that are of most importance in conferring resistance to specific compounds. The resistance-nodulation-division (RND) protein family is one such example of redundant transporters that are widespread among Gram-negative bacteria. Within this family, the MexAB-OprM protein complex is highly expressed and conserved among Pseudomonas species. We exposed barcoded transposon mutant libraries in isogenic wild-type and ΔmexB backgrounds in P. syringae B728a to diverse toxic compounds in vitro to identify mutants with increased susceptibility to these compounds. Mutants with mutations in genes encoding both known and novel redundant transporters but with partially overlapping substrate specificities were observed in a ΔmexB background. Psyr_0228, an uncharacterized member of the major facilitator superfamily of transporters, preferentially contributes to tolerance of acridine orange and acriflavine. Another transporter located in the inner membrane, Psyr_0541, contributes to tolerance of acriflavine and berberine. The presence of multiple redundant, genomically encoded efflux transporters appears to enable bacterial strains to tolerate a diversity of environmental toxins. This genome-wide screen performed in a hypersusceptible mutant strain revealed numerous transporters that would otherwise be dispensable under these conditions. Bacterial strains such as P. syringae that likely encounter diverse toxins in their environment, such as in association with many different plant species, probably benefit from possessing multiple redundant transporters that enable versatility with respect to toleration of novel toxicants.IMPORTANCE Bacteria use protein pumps to remove toxic compounds from the cell interior, enabling survival in diverse environments. These protein pumps can be highly redundant, making their targeted examination difficult. In this study, we exposed mutant populations of Pseudomonas syringae to diverse toxicants to identify pumps that contributed to survival in those conditions. In parallel, we examined pump redundancy by testing mutants of a population lacking the primary efflux transporter responsible for toxin tolerance. We identified partial substrate overlap for redundant transporters, as well as several pumps that appeared more substrate specific. For bacteria that are found in diverse environments, having multiple, partially redundant efflux pumps likely allows flexibility in habitat colonization.
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Affiliation(s)
- Tyler C Helmann
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
| | - Caitlin L Ongsarte
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
| | - Jennifer Lam
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
| | - Adam M Deutschbauer
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Steven E Lindow
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, USA
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Traore SM, Eckshtain‐Levi N, Miao J, Castro Sparks A, Wang Z, Wang K, Li Q, Burdman S, Walcott R, Welbaum GE, Zhao B. Nicotiana species as surrogate host for studying the pathogenicity of Acidovorax citrulli, the causal agent of bacterial fruit blotch of cucurbits. MOLECULAR PLANT PATHOLOGY 2019; 20:800-814. [PMID: 30938096 PMCID: PMC6637898 DOI: 10.1111/mpp.12792] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Bacterial fruit blotch (BFB) caused by Acidovorax citrulli is one of the most important bacterial diseases of cucurbits worldwide. However, the mechanisms associated with A. citrulli pathogenicity and genetics of host resistance have not been extensively investigated. We idenitfied Nicotiana benthamiana and Nicotiana tabacum as surrogate hosts for studying A. citrulli pathogenicity and non-host resistance triggered by type III secreted (T3S) effectors. Two A. citrulli strains, M6 and AAC00-1, that represent the two major groups amongst A. citrulli populations, induced disease symptoms on N. benthamiana, but triggered a hypersensitive response (HR) on N. tabacum plants. Transient expression of 19 T3S effectors from A. citrulli in N. benthamiana leaves revealed that three effectors, Aave_1548, Aave_2708, and Aave_2166, trigger water-soaking-like cell death in N. benthamiana. Aave_1548 knockout mutants of M6 and AAC00-1 displayed reduced virulence on N. benthamiana and melon (Cucumis melo L.). Transient expression of Aave_1548 and Aave_2166 effectors triggered a non-host HR in N. tabacum, which was dependent on the functionality of the immune signalling component, NtSGT1. Hence, employing Nicotiana species as surrogate hosts for studying A. citrulli pathogenicity may help characterize the function of A. citrulli T3S effectors and facilitate the development of new strategies for BFB management.
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Affiliation(s)
- Sy M. Traore
- School of Plant and Environmental SciencesVirginia TechBlacksburgVAUSA
| | - Noam Eckshtain‐Levi
- Department of Plant Pathology and MicrobiologyThe Hebrew University of JerusalemRehovotIsrael
| | - Jiamin Miao
- School of Plant and Environmental SciencesVirginia TechBlacksburgVAUSA
| | | | - Zhibo Wang
- School of Plant and Environmental SciencesVirginia TechBlacksburgVAUSA
| | - Kunru Wang
- School of Plant and Environmental SciencesVirginia TechBlacksburgVAUSA
| | - Qi Li
- School of Plant and Environmental SciencesVirginia TechBlacksburgVAUSA
| | - Saul Burdman
- Department of Plant Pathology and MicrobiologyThe Hebrew University of JerusalemRehovotIsrael
| | - Ron Walcott
- Department of Plant PathologyUniversity of GeorgiaAthensGAUSA
| | | | - Bingyu Zhao
- School of Plant and Environmental SciencesVirginia TechBlacksburgVAUSA
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Wang H, McTavish C, Turechek WW. Colonization and Movement of Xanthomonas fragariae in Strawberry Tissues. PHYTOPATHOLOGY 2018; 108:681-690. [PMID: 29298111 DOI: 10.1094/phyto-10-17-0356-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Xanthomonas fragariae causes angular leaf spot of strawberry, an important disease in strawberry growing regions worldwide. To better understand how X. fragariae multiplies and moves in strawberry plants, a green fluorescent protein (GFP)-labeled strain was constructed and used to monitor the pathogen's presence in leaf, petiole, and crown tissue with fluorescence microscopy following natural and wound inoculation in three strawberry cultivars. Taqman PCR was used to quantify bacterial densities in these same tissues regardless of the presence of GFP signal. Results showed X. fragariae colonized leaf mesophyll, the top 1 cm portion of the petiole adjacent to the leaf blade, and was occasionally found colonizing xylem vessels down to the middle of the petioles. The colonization of vascular bundles and the limited systemic movement that was observed appeared to be a passive process, of which the frequency increased with wounding and direct infiltration of bacteria into leaf veins. X. fragariae was able to directly enter petioles and colonize the space under the epidermis. Systemic movement of the bacteria into crown and other uninoculated tissues was not detected visually by GFP. However, X. fragariae was occasionally detected in these tissues by qPCR, but at quantities very near the qPCR detection limit. Petiole tissue harboring bacteria introduced either by direct entry through natural openings or wounds, or by systemic movement from infected foliar tissue, likely serves as a main source of initial inoculum in field plantings.
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Affiliation(s)
- Hehe Wang
- First author: Department of Plant and Environmental Sciences, Clemson University, Blackville, SC; second author: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Physiology and Pathology of Tree Fruits Research, Wenatchee, WA; and third author: USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, FL
| | - Christine McTavish
- First author: Department of Plant and Environmental Sciences, Clemson University, Blackville, SC; second author: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Physiology and Pathology of Tree Fruits Research, Wenatchee, WA; and third author: USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, FL
| | - William W Turechek
- First author: Department of Plant and Environmental Sciences, Clemson University, Blackville, SC; second author: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Physiology and Pathology of Tree Fruits Research, Wenatchee, WA; and third author: USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, FL
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Tavares MJ, Nascimento FX, Glick BR, Rossi MJ. The expression of an exogenous ACC deaminase by the endophyte Serratia grimesii BXF1 promotes the early nodulation and growth of common bean. Lett Appl Microbiol 2018; 66:252-259. [PMID: 29327464 DOI: 10.1111/lam.12847] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 12/28/2017] [Accepted: 01/04/2018] [Indexed: 11/28/2022]
Abstract
Ethylene acts as an inhibitor of the nodulation process of leguminous plants. However, some bacteria can decrease deleterious ethylene levels by the action of the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase which degrades ACC, the ethylene precursor in all higher plants. Co-inoculation of rhizobia with endophytes enhances the rhizobial symbiotic efficiency with legumes, improving both nodulation and nitrogen fixation. However, not much is understood about the mechanisms employed by these endophytic bacteria. In this regard, the role of ACC deaminase from endophytic strains in assisting rhizobia in this process has yet to be confirmed. In this study, the role of ACC deaminase in an endophyte's ability to increase Rhizobium tropici nodulation of common bean was evaluated. To assess the effect of ACC deaminase in an endophyte's ability to promote rhizobial nodulation, the endophyte Serratia grimesii BXF1, which does not encode ACC deaminase, was transformed with an exogenous acdS gene. The results obtained indicate that the ACC deaminase-overexpressing transformant strain increased common bean growth, and enhanced the nodulation abilities of R. tropici CIAT899, in both cases compared to the wild-type non-transformed strain. Furthermore, plant inoculation with the ACC deaminase-overproducing strain led to an increased level of plant protection against a seed-borne pathogen. SIGNIFICANCE AND IMPACT OF THE STUDY In this work, we studied the effect of ACC deaminase production by the bacterial endophyte Serratia grimesi BXF1, and its impact on the nodulation process of common bean. The results obtained indicate that ACC deaminase is an asset to the synergetic interaction between rhizobia and the endophyte, positively contributing to the overall legume-rhizobia symbiosis by regulating inhibitory ethylene levels that might otherwise inhibit nodulation and overall plant growth. The use of rhizobia together with an ACC deaminase-producing endophyte is, therefore, an important strategy for the development of new bacterial inoculants with increased performance.
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Affiliation(s)
- M J Tavares
- Departamento de Microbiologia, MIP-CCB, Laboratório de Bioprocessos, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - F X Nascimento
- Departamento de Microbiologia, MIP-CCB, Laboratório de Bioprocessos, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - B R Glick
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - M J Rossi
- Departamento de Microbiologia, MIP-CCB, Laboratório de Bioprocessos, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
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13
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Nascimento FX, Espada M, Barbosa P, Rossi MJ, Vicente CSL, Mota M. Non-specific transient mutualism between the plant parasitic nematode,Bursaphelenchus xylophilus, and the opportunistic bacteriumSerratia quinivoransBXF1, a plant-growth promoting pine endophyte with antagonistic effects. Environ Microbiol 2016; 18:5265-5276. [DOI: 10.1111/1462-2920.13568] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 10/04/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Francisco X. Nascimento
- Nemalab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia; Universidade de Évora; Núcleo da Mitra, Ap. 94 Évora 7002-554 Portugal
- Departamento de Microbiologia, Laboratório de Microbiologia do Solo; Universidade Federal de Santa Catarina; Florianópolis SC 88040-900 Brazil
| | - Margarida Espada
- Nemalab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia; Universidade de Évora; Núcleo da Mitra, Ap. 94 Évora 7002-554 Portugal
| | - Pedro Barbosa
- Nemalab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia; Universidade de Évora; Núcleo da Mitra, Ap. 94 Évora 7002-554 Portugal
| | - Márcio J. Rossi
- Departamento de Microbiologia, Laboratório de Microbiologia do Solo; Universidade Federal de Santa Catarina; Florianópolis SC 88040-900 Brazil
| | - Cláudia S. L. Vicente
- Nemalab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia; Universidade de Évora; Núcleo da Mitra, Ap. 94 Évora 7002-554 Portugal
- Department of Environmental Biology College of Bioscience & Biotechnology; Chubu University; 1200 Matsumoto Kasugai Aichi 487-8501 Japan
| | - Manuel Mota
- Nemalab/ICAAM - Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Departamento de Biologia; Universidade de Évora; Núcleo da Mitra, Ap. 94 Évora 7002-554 Portugal
- Departamento Ciências da Vida; EPCV Universidade Lusófona de Humanidades e Tecnologias; C. Grande 376 Lisboa 1749-024 Portugal
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Liu Y, Miao J, Traore S, Kong D, Liu Y, Zhang X, Nimchuk ZL, Liu Z, Zhao B. SacB-SacR Gene Cassette As the Negative Selection Marker to Suppress Agrobacterium Overgrowth in Agrobacterium-Mediated Plant Transformation. Front Mol Biosci 2016; 3:70. [PMID: 27833912 PMCID: PMC5080373 DOI: 10.3389/fmolb.2016.00070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/07/2016] [Indexed: 11/13/2022] Open
Abstract
Agrobacterium overgrowth is a common problem in Agrobacterium-mediated plant transformation. To suppress the Agrobacterium overgrowth, various antibiotics have been used during plant tissue culture steps. The antibiotics are expensive and may adversely affect plant cell differentiation and reduce plant transformation efficiency. The SacB-SacR proteins are toxic to most Agrobacterium tumefaciens strains when they are grown on culture medium supplemented with sucrose. Therefore, SacB-SacR genes can be used as negative selection markers to suppress the overgrowth of A. tumefaciens in the plant tissue culture process. We generated a mutant A. tumefaciens strain GV2260 (recA-SacB/R) that has the SacB-SacR cassette inserted into the bacterial genome at the recA gene locus. The mutant Agrobacterium strain is sensitive to sucrose but maintains its ability to transform plant cells in both transient and stable transformation assays. We demonstrated that the mutant strain GV2260 (recA-SacB/R) can be inhibited by sucrose that reduces the overgrowth of Agrobacterium and therefore improves the plant transformation efficiency. We employed GV2260 (recA-SacB/R) to generate stable transgenic N. benthamiana plants expressing a CRISPR-Cas9 for knocking out a WRKY transcription factor.
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Affiliation(s)
- Yiming Liu
- Department of Crop and Soil Environmental Science, Virginia TechBlacksburg, VA, USA; Chinese Academy of Tropical Agricultural Sciences/Key Laboratory of Crop Gene Resources and Germplasm Enhancement in Southern China, Tropical Crops Genetic Resources Institute, Ministry of AgricultureDanzhou, China
| | - Jiamin Miao
- Department of Horticulture, Virginia Tech Blacksburg, VA, USA
| | - Sy Traore
- Department of Horticulture, Virginia Tech Blacksburg, VA, USA
| | - Danyu Kong
- Department of Horticulture, Virginia Tech Blacksburg, VA, USA
| | - Yi Liu
- Department of Horticulture, Virginia Tech Blacksburg, VA, USA
| | - Xunzhong Zhang
- Department of Crop and Soil Environmental Science, Virginia Tech Blacksburg, VA, USA
| | - Zachary L Nimchuk
- Department of Biology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Zongrang Liu
- USDA-ARS-Appalachian Fruit Research Station Kearneysville, WV, USA
| | - Bingyu Zhao
- Department of Horticulture, Virginia Tech Blacksburg, VA, USA
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15
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Ali M, Sun Y, Xie L, Yu H, Bashir A, Li L. The Pathogenicity of Pseudomonas syringae MB03 against Caenorhabditis elegans and the Transcriptional Response of Nematicidal Genes upon Different Nutritional Conditions. Front Microbiol 2016; 7:805. [PMID: 27303387 PMCID: PMC4884745 DOI: 10.3389/fmicb.2016.00805] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 05/12/2016] [Indexed: 12/22/2022] Open
Abstract
Different species of the Pseudomonas genus have been reported for their pathogenic potential against animal cells. However, the pathogenicity of Pseudomonas syringae against Caenorhabditis elegans has never been reported. In this study, the interaction of P. syringae MB03 with C. elegans was studied. Different bioassays such as killing assay, lawn leaving assay, food preference assay, L4 growth assay and newly developed “secretion assay” were performed to evaluate the pathogenic potential of P. syringae on different growth media. The results of the killing assay showed that P. syringae MB03 was able to kill C. elegans under specific conditions, as the interaction between the host and the pathogen varied from non-pathogenic (assay on NGM medium) to pathogenic (assay on PG medium). The lawn leaving assay and the food preference assay illustrated that C. elegans identified P. syringae MB03 as a pathogen when assays were performed on PG medium. Green fluorescent protein was used as the reporter protein to study gut colonization by P. syringae MB03. Our results suggested that MB03 has the ability to colonize the gut of C. elegans. Furthermore, to probe the role of selected virulence determinants, qRT-PCR was used. The genes for pyoverdine, phoQ/phoP, phoR/phoB, and flagella were up regulated during the interaction of P. syringae MB03 and C. elegans on PG medium. Other than these, the genes for some proteases, such as pepP, clpA, and clpS, were also up regulated. On the other hand, kdpD and kdpB were down regulated more than threefold in the NGM – C. elegans interaction model. The deletion of the kdpD and kdpE genes altered the pathogenicity of the bacterial strain against C. elegans. Overall, our results suggested that the killing of C. elegans by P. syringae requires a prolonged interaction between the host and pathogen in an agar-based assay. Moreover, it seemed that some toxic metabolites were secreted by the bacterial strain that were sensed by C. elegans. Previously, it was believed that P. syringae could not damage animal cells. However, this study provides evidence of the pathogenic behavior of P. syringae against C. elegans.
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Affiliation(s)
- Muhammad Ali
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China; Biotechnology Program, Department of Environmental Sciences, COMSATS Institute of Information TechnologyAbbottabad, Pakistan
| | - Yu Sun
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Li Xie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Huafu Yu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Anum Bashir
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Lin Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
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16
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Kukavica-Ibrulj I, Levesque RC. Essential genes in the infection model of Pseudomonas aeruginosa-PCR-based signature-tagged mutagenesis. Methods Mol Biol 2015; 1279:97-123. [PMID: 25636615 DOI: 10.1007/978-1-4939-2398-4_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PCR-based signature tagged mutagenesis is an "en masse" screening technique based upon unique oligonucleotide tags (molecular barcodes) for identification of genes that will diminish or enhance maintenance of an organism in a specific ecological niche or environment. PCR-based STM applied to Pseudomonas aeruginosa permitted the identification of genes essential for in vivo maintenance by transposon insertion and negative selection in a mixed population of bacterial mutants. The innovative adaptations and refinement of the technology presented here with P. aeruginosa STM mutants selected in the rat model of chronic lung infection have given critical information about genes essential for causing a chronic infection and a wealth of information about biological processes in vivo. The additional use of competitive index analysis for measurement of the level of virulence in vivo, microarray-based screening of selected prioritized STM mutants coupled to metabolomics analysis can now be attempted systematically on a genomic scale. PCR-based STM and combined whole-genome methods can also be applied to any organism having selectable phenotypes for screening.
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Affiliation(s)
- Irena Kukavica-Ibrulj
- Institut de biologie intégrative et des systèmes (IBIS), Faculté de Médecine, Université Laval, Pavillon Charles-Eugène Marchand, 1030 Avenue de la médecine, Québec, QC, Canada, G1K 7P4
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17
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Synergism of regulatory elements in σB- and σA-dependent promoters enhances recombinant protein expression in Bacillus subtilis. J Biosci Bioeng 2015; 120:470-5. [DOI: 10.1016/j.jbiosc.2015.02.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 01/05/2015] [Accepted: 02/08/2015] [Indexed: 11/22/2022]
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18
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Ledermann R, Bartsch I, Remus-Emsermann MN, Vorholt JA, Fischer HM. Stable Fluorescent and Enzymatic Tagging of Bradyrhizobium diazoefficiens to Analyze Host-Plant Infection and Colonization. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:959-67. [PMID: 26035130 DOI: 10.1094/mpmi-03-15-0054-ta] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Bradyrhizobium diazoefficiens USDA 110 (formerly named Bradyrhizobium japonicum) can fix dinitrogen when living as an endosymbiont in root nodules of soybean and some other legumes. Formation of a functional symbiosis relies on a defined developmental program mediated by controlled gene expression in both symbiotic partners. In contrast to other well-studied Rhizobium-legume model systems that have been thoroughly examined by means of genetically tagged strains, analysis of B. diazoefficiens host infection has been impaired due to the lack of suitable tagging systems. Here, we describe the construction of B. diazoefficiens strains constitutively expressing single-copy genes for fluorescent proteins (eBFP2, mTurquoise2, GFP+, sYFP2, mCherry, HcRed) and enzymes (GusA, LacZ). For stable inheritance, the constructs were recombined into the chromosome. Effectiveness and versatility of the tagged strains was demonstrated in plant infection assays. (i) The infection process was followed from root-hair attachment to colonization of nodule cells with epifluorescent microscopy. (ii) Monitoring mixed infections with two strains producing different fluorescent proteins allowed rapid analysis of nodule occupancy and revealed that the majority of nodules contained clonal populations. (iii) Microscopic analysis of nodules induced by fluorescent strains provided evidence for host-dependent control of B. diazoefficiens bacteroid morphology in nodules of Aeschynomene afraspera and Arachis hypogaea (peanut), as deduced from their altered morphology compared with bacteroids in soybean nodules.
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Affiliation(s)
- Raphael Ledermann
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Ilka Bartsch
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | | | - Julia A Vorholt
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Hans-Martin Fischer
- ETH Zurich, Institute of Microbiology, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
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19
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Giles SK, Stroeher UH, Eijkelkamp BA, Brown MH. Identification of genes essential for pellicle formation in Acinetobacter baumannii. BMC Microbiol 2015; 15:116. [PMID: 26047954 PMCID: PMC4457973 DOI: 10.1186/s12866-015-0440-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/11/2015] [Indexed: 12/11/2022] Open
Abstract
Background Acinetobacter baumannii is an opportunistic pathogen, which has the ability to persist in the clinical environment, causing acute and chronic infections. A possible mechanism contributing to survival of A. baumannii is its ability to form a biofilm-like structure at the air/liquid interface, known as a pellicle. This study aimed to identify and characterise the molecular mechanisms required for pellicle formation in A. baumannii and to assess a broad range of clinical A. baumannii strains for their ability to form these multicellular structures. Results Random transposon mutagenesis was undertaken on a previously identified hyper-motile variant of A. baumannii ATCC 17978 designated 17978hm. In total three genes critical for pellicle formation were identified; cpdA, a phosphodiesterase required for degradation of cyclic adenosine monophosphate (cAMP), and A1S_0112 and A1S_0115 which are involved in the production of a secondary metabolite. While motility of the A1S_0112::Tn and A1S_0115::Tn mutant strains was abolished, the cpdA::Tn mutant strain displayed a minor alteration in its motility pattern. Determination of cAMP levels in the cpdA::Tn strain revealed a ~24-fold increase in cellular cAMP, confirming the role CpdA plays in catabolising this secondary messenger molecule. Interestingly, transcriptional analysis of the cpdA::Tn strain showed significant down-regulation of the operon harboring the A1S_0112 and A1S_0115 genes, revealing a link between these three genes and pellicle formation. Examination of our collection of 54 clinical A. baumannii strains revealed that eight formed a measurable pellicle; all of these strains were motile. Conclusions This study shows that pellicle formation is a rare trait in A. baumannii and that a limited number of genes are essential for the expression of this phenotype. Additionally, an association between pellicle formation and motility was identified. The level of the signalling molecule cAMP was found to be controlled, in part, by the cpdA gene product, in addition to playing a critical role in pellicle formation, cellular hydrophobicity and motility. Furthermore, cAMP was identified as a novel regulator of the operon A1S_0112-0118. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0440-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sarah K Giles
- School of Biological Sciences, Flinders University, GPO Box 2100, 5001, Adelaide, SA, Australia.
| | - Uwe H Stroeher
- School of Biological Sciences, Flinders University, GPO Box 2100, 5001, Adelaide, SA, Australia.
| | - Bart A Eijkelkamp
- School of Biological Sciences, Flinders University, GPO Box 2100, 5001, Adelaide, SA, Australia. .,Research Centre for Infectious Diseases, School of Biological Sciences University of Adelaide, Adelaide, Australia.
| | - Melissa H Brown
- School of Biological Sciences, Flinders University, GPO Box 2100, 5001, Adelaide, SA, Australia.
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20
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Gengler S, Batoko H, Wattiau P. Method for fluorescent marker swapping and its application in Steinernema nematode colonization studies. J Microbiol Methods 2015; 113:34-7. [PMID: 25835465 DOI: 10.1016/j.mimet.2015.03.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 03/27/2015] [Accepted: 03/29/2015] [Indexed: 10/23/2022]
Abstract
An allelic exchange vector was constructed to replace gfp by mCherry in bacteria previously tagged with mini-Tn5 derivatives. The method was successfully applied to a gfp-labeled Yersinia pseudotuberculosis strain and the re-engineered bacterium was used to study the colonization of Steinernema nematodes hosting their Xenorhabdus symbiont using dual-color confocal microscopy.
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Affiliation(s)
- Samuel Gengler
- Veterinary & Agrochemical Research Centre, Brussels, Belgium; Institute of life sciences (ISV), Catholic University of Louvain-la-Neuve (UCL), Belgium
| | - Henri Batoko
- Institute of life sciences (ISV), Catholic University of Louvain-la-Neuve (UCL), Belgium
| | - Pierre Wattiau
- Veterinary & Agrochemical Research Centre, Brussels, Belgium.
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21
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Mathews SL, Smith RB, Matthysse AG. A comparison of the retention of pathogenic Escherichia coli O157 by sprouts, leaves and fruits. Microb Biotechnol 2014; 7:570-9. [PMID: 25351040 PMCID: PMC4265075 DOI: 10.1111/1751-7915.12165] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 07/31/2014] [Accepted: 08/11/2014] [Indexed: 11/30/2022] Open
Abstract
The retention (binding to or association with the plant) of Escherichia coli by cut leaves and fruits after vigorous water washing was compared with that by sprouts. Retention by fruits and leaves was similar but differed from retention by sprouts in rate, effect of wounding and requirement for poly-β,1-6-N-acetyl-D-glucosamine. Escherichia coli was retained by cut ends of lettuce leaves within 5 min while more than 1 h was required for retention by the intact epidermis of leaves and fruits, and more than 1 day for sprouts. Retention after 5 min at the cut leaf edge was specific for E. coli and was not shown by the plant-associated bacteria Agrobacterium tumefaciens and Sinorhizobium meliloti. Escherichia coli was retained by lettuce, spinach, alfalfa, bean, tomato, Arabidopsis thaliana, cucumber, and pepper leaves and fruits faster than by sprouts. Wounding of leaves and fruits but not sprouts increased bacterial retention. Mutations in the exopolysaccharide synthesis genes yhjN and wcaD reduced the numbers of bacteria retained. PgaC mutants were retained by cut leaves and fruits but not by sprouts. There was no significant difference in the retention of an O157 and a K12 strain by fruits or leaves. However, retention by sprouts of O157 strains was significantly greater than K12 strains. These findings suggest that there are differences in the mechanisms of E coli retention among sprouts, and leaves and fruits.
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Affiliation(s)
| | - Rachel B Smith
- Department of Biology, University of North CarolinaChapel Hill, NC, 27599-3280, USA
| | - Ann G Matthysse
- Department of Biology, University of North CarolinaChapel Hill, NC, 27599-3280, USA
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Burch AY, Zeisler V, Yokota K, Schreiber L, Lindow SE. The hygroscopic biosurfactant syringafactin produced by Pseudomonas syringae enhances fitness on leaf surfaces during fluctuating humidity. Environ Microbiol 2014; 16:2086-98. [PMID: 24571678 DOI: 10.1111/1462-2920.12437] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 02/18/2014] [Indexed: 11/27/2022]
Abstract
Biosurfactant production by bacteria on leaf surfaces is poorly documented, and its role in this habitat has not been explored. Therefore, we investigated the production and fitness benefits of syringafactin by Pseudomonas syringae pv. syringae B728a on leaves. Syringafactin largely adsorbed to the waxy leaf cuticle both when topically applied and when produced by cells on plants. Syringafactin increased the rate of diffusion of water across isolated cuticles and attracted water to hydrophobic surfaces exposed to high relative humidity due to its hygroscopic properties. While a wild-type and syringafactin mutant exhibited similar fitness on bean leaves incubated in static conditions, the fitness of the wild-type strain was higher under fluctuating humidity conditions typical of field conditions. When co-inoculated onto either the host plant bean or the non-host plant romaine lettuce, the proportion of viable wild-type cells recovered from plants relative to that of a mutant unable to produce syringafactin increased 10% over 10 days. The number of disease lesions incited by the wild-type strain on bean was also significantly higher than that of the syringafactin mutant. The production of hygroscopic biosurfactants on waxy leaf surfaces apparently benefits bacteria by both attracting moisture and facilitating access to nutrients.
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Affiliation(s)
- Adrien Y Burch
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
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23
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Abstract
Signature-tagged mutagenesis (STM) is a genome-wide functional screening assay based upon an insertional mutation technique to identify mutants having a particular phenotype from a mixed population. The selection phenotype is either negative or positive for identification of mutations in genes which will impact the host as having a diminished or enhanced adaptation to a defined environment. STM has subsequently been used in different biological systems and adapted to use different mutagens, signature tags, and detection methods. Here, STM has been modified and used for genome-wide screening of Pseudomonas aeruginosa to identify genes and their products essential during the infection process or in enhancing virulence in vivo.
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Affiliation(s)
- Irena Kukavica-Ibrulj
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, 1030 av. de la médecine, Québec, QC, Canada, G1V 0A6
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Zúñiga A, Poupin MJ, Donoso R, Ledger T, Guiliani N, Gutiérrez RA, González B. Quorum sensing and indole-3-acetic acid degradation play a role in colonization and plant growth promotion of Arabidopsis thaliana by Burkholderia phytofirmans PsJN. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:546-53. [PMID: 23301615 DOI: 10.1094/mpmi-10-12-0241-r] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Although not fully understood, molecular communication in the rhizosphere plays an important role regulating traits involved in plant-bacteria association. Burkholderia phytofirmans PsJN is a well-known plant-growth-promoting bacterium, which establishes rhizospheric and endophytic colonization in different plants. A competent colonization is essential for plant-growth-promoting effects produced by bacteria. Using appropriate mutant strains of B. phytofirmans, we obtained evidence for the importance of N-acyl homoserine lactone-mediated (quorum sensing) cell-to-cell communication in efficient colonization of Arabidopsis thaliana plants and the establishment of a beneficial interaction. We also observed that bacterial degradation of the auxin indole-3-acetic acid (IAA) plays a key role in plant-growth-promoting traits and is necessary for efficient rhizosphere colonization. Wildtype B. phytofirmans but not the iacC mutant in IAA mineralization is able to restore promotion effects in roots of A. thaliana in the presence of exogenously added IAA, indicating the importance of this trait for promoting primary root length. Using a transgenic A. thaliana line with suppressed auxin signaling (miR393) and analyzing the expression of auxin receptors in wild-type inoculated plants, we provide evidence that auxin signaling in plants is necessary for the growth promotion effects produced by B. phytofirmans. The interplay between ethylene and auxin signaling was also confirmed by the response of the plant to a 1-aminocyclopropane-1-carboxylate deaminase bacterial mutant strain.
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Affiliation(s)
- Ana Zúñiga
- Universidad Adolfo Ibanez, Santiago, Chile
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25
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Halgren A, Maselko M, Azevedo M, Mills D, Armstrong D, Banowetz G. Genetics of germination-arrest factor (GAF) production by Pseudomonas fluorescens WH6: identification of a gene cluster essential for GAF biosynthesis. Microbiology (Reading) 2013; 159:36-45. [DOI: 10.1099/mic.0.062166-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Anne Halgren
- USDA-ARS National Forage Seed Production Research Center, Corvallis, OR 97331, USA
| | - Maciej Maselko
- USDA-ARS National Forage Seed Production Research Center, Corvallis, OR 97331, USA
| | - Mark Azevedo
- USDA-ARS National Forage Seed Production Research Center, Corvallis, OR 97331, USA
| | - Dallice Mills
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Donald Armstrong
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Gary Banowetz
- USDA-ARS National Forage Seed Production Research Center, Corvallis, OR 97331, USA
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26
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Sun F, Gao H, Zhang Y, Wang L, Fang N, Tan Y, Guo Z, Xia P, Zhou D, Yang R. Fur is a repressor of biofilm formation in Yersinia pestis. PLoS One 2012; 7:e52392. [PMID: 23285021 PMCID: PMC3528687 DOI: 10.1371/journal.pone.0052392] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 11/13/2012] [Indexed: 11/29/2022] Open
Abstract
Background Yersinia pestis synthesizes the attached biofilms in the flea proventriculus, which is important for the transmission of this pathogen by fleas. The hmsHFRS operons is responsible for the synthesis of exopolysaccharide (the major component of biofilm matrix), which is activated by the signaling molecule 3′, 5′-cyclic diguanylic acid (c-di-GMP) synthesized by the only two diguanylate cyclases HmsT, and YPO0449 (located in a putative operonYPO0450-0448). Methodology/Principal Findings The phenotypic assays indicated that the transcriptional regulator Fur inhibited the Y. pestis biofilm production in vitro and on nematode. Two distinct Fur box-like sequences were predicted within the promoter-proximal region of hmsT, suggesting that hmsT might be a direct Fur target. The subsequent primer extension, LacZ fusion, electrophoretic mobility shift, and DNase I footprinting assays disclosed that Fur specifically bound to the hmsT promoter-proximal region for repressing the hmsT transcription. In contrast, Fur had no regulatory effect on hmsHFRS and YPO0450-0448 at the transcriptional level. The detection of intracellular c-di-GMP levels revealed that Fur inhibited the c-di-GMP production. Conclusions/Significance Y. pestis Fur inhibits the c-di-GMP production through directly repressing the transcription of hmsT, and thus it acts as a repressor of biofilm formation. Since the relevant genetic contents for fur, hmsT, hmsHFRS, and YPO0450-0448 are extremely conserved between Y. pestis and typical Y. pseudotuberculosis, the above regulatory mechanisms can be applied to Y. pseudotuberculosis.
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Affiliation(s)
- Fengjun Sun
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- Department of Pharmacy, Southwest Hospital, the Third Military Medical University, Chongqing, China
| | - He Gao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Centre for Disease Control and Prevention, Beijing, China
| | - Yiquan Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Li Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Nan Fang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yafang Tan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zhaobiao Guo
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Peiyuan Xia
- Department of Pharmacy, Southwest Hospital, the Third Military Medical University, Chongqing, China
- * E-mail: (PX); (DZ); (RY)
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (PX); (DZ); (RY)
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (PX); (DZ); (RY)
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27
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Diverse microhabitats experienced by Halomonas variabilis on salt-secreting leaves. Appl Environ Microbiol 2012; 79:845-52. [PMID: 23160133 DOI: 10.1128/aem.02791-12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The leaf surfaces of the salt-excreting tree Tamarix aphylla harbor a wide diversity of halophilic microorganisms, including Halomonas sp., but little is known of the factors that shape community composition in this extreme habitat. We isolated a strain of Halomonas variabilis from the leaf surface of T. aphylla and used it to determine the heterogeneity of salt concentrations experienced by bacteria in this environment. This halophilic strain was transformed with a proU::gfp reporter gene fusion, the fluorescence of which was responsive to NaCl concentrations up to 200 g liter(-1). These bioreporting cells were applied to T. aphylla leaves and were subsequently recovered from dew droplets adhering to the leaf surface. Although cells from within a given dew droplet exhibited similar green fluorescent protein fluorescence, the fluorescence intensity varied between droplets and was correlated with the salt concentration measured in each drop. Growth of H. variabilis was observed in all droplets, regardless of the salt concentration. However, cells found in desiccated microniches between dew drops were low in abundance and generally dead. Other bacteria recovered from T. aphylla displayed higher desiccation tolerance than H. variabilis, both in culture and on inoculated plants, despite having lower osmotic tolerance. Thus, the Tamarix leaf surface can be described as a salty desert with occasional oases where water droplets form under humid conditions. While halotolerant bacteria such as Halomonas grow in high concentrations of salt in such wet microniches, other organisms are better suited to survive desiccation in sites that are not wetted.
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28
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Mitchell AC, Peterson L, Reardon CL, Reed SB, Culley DE, Romine MR, Geesey GG. Role of outer membrane c-type cytochromes MtrC and OmcA in Shewanella oneidensis MR-1 cell production, accumulation, and detachment during respiration on hematite. GEOBIOLOGY 2012; 10:355-370. [PMID: 22360295 DOI: 10.1111/j.1472-4669.2012.00321.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The iron-reducing bacterium Shewanella oneidensis MR-1 has the capacity to contribute to iron cycling over the long term by respiring on crystalline iron oxides such as hematite when poorly crystalline phases are depleted. The ability of outer membrane cytochromes OmcA and MtrC of MR-1 to bind to and transfer electrons to hematite has led to the suggestion that they function as terminal reductases when this mineral is used as a respiratory substrate. Differences in their redox behavior and hematite-binding properties, however, indicate that they play different roles in the electron transfer reaction. Here, we investigated how these differences in cytochrome behavior with respect to hematite affected biofilm development when the mineral served as terminal electron acceptor (TEA). Upon attachment to hematite, cells of the wild-type (WT) strain as well as those of a ΔomcA mutant but not those of a ΔmtrC mutant replicated and accumulated on the mineral surface. The results indicate that MtrC but not OmcA is required for growth when this mineral serves as TEA. While an OmcA deficiency did not impede cell replication and accumulation on hematite prior to achievement of a maximum surface cell density comparable to that established by WT cells, OmcA was required for efficient electron transfer and cell attachment to hematite once maximum surface cell density was achieved. OmcA may therefore play a role in overcoming barriers to electron transfer and cell attachment to hematite imposed by reductive dissolution of the mineral surface from cell respiration associated with achievement of high surface cell densities.
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Affiliation(s)
- A C Mitchell
- Department of Microbiology and Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
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29
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Chen WM, Prell J, James EK, Sheu DS, Sheu SY. Biosynthesis of branched-chain amino acids is essential for effective symbioses between betarhizobia and Mimosa pudica. MICROBIOLOGY-SGM 2012; 158:1758-1766. [PMID: 22556357 DOI: 10.1099/mic.0.058370-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia phymatum STM815 and Cupriavidus taiwanensis LMG19424 are betaproteobacterial strains that can effectively nodulate several species of the large legume genus Mimosa. A Tn5 mutant, derived from B. phymatum STM815 (KM60), and another derived from C. taiwanensis LMG19424 (KM184-55) induced Fix(-) nodules on Mimosa pudica. The Tn5-interrupted genes of the mutants showed strong homologies to ilvE, which encodes a branched-chain amino acid aminotransferase, and leuC, which encodes the large subunit of isopropylmalate isomerase. Both enzymes are known to be involved in the biosynthetic pathways for branched-chain amino acids (BCAAs) (leucine, valine and isoleucine). The B. phymatum ilvE mutant, KM60, was not auxotrophic for BCAAs and could grow well on minimal medium with pyruvate as a carbon source and ammonia as a nitrogen source. However, it grew less efficiently than the wild-type (WT) strain when ammonia was substituted with valine or isoleucine as a nitrogen source. The BCAA aminotransferase activity of KM60 was significantly reduced relative to the WT strain, especially with isoleucine and valine as amino group donors. The C. taiwanensis leuC mutant, KM184-55, could not grow on a minimal medium with pyruvate as a carbon source and ammonia as a nitrogen source, but its growth was restored when leucine was added to the medium. The isopropylmalate isomerase activity of KM184-55 was completely lost compared with the WT strain. Both mutants recovered their respective enzyme activities after complementation with the WT ilvE or leuC genes and were subsequently able to grow as well as their parental strains on minimal medium. They were also able to form nitrogen-fixing nodules on M. pudica. We conclude that the biosynthesis of BCAAs is essential for the free-living growth of betarhizobia, as well as for their ability to form effective symbioses with their host plant.
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Affiliation(s)
- Wen-Ming Chen
- Laboratory of Microbiology, Department of Seafood Science, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC
| | - Jurgen Prell
- Soil Ecology, Department of Botany, RWTH Aachen, 52056 Aachen, Germany
| | - Euan K James
- The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Der-Shyan Sheu
- Department of Marine Biotechnology, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC
| | - Shih-Yi Sheu
- Department of Marine Biotechnology, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC
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30
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Fate of invading bacteria in soil and survival of transformants after simulated uptake of transgenes, as evaluated by a model system based on lindane degradation. Res Microbiol 2012; 163:200-10. [DOI: 10.1016/j.resmic.2012.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 01/19/2012] [Indexed: 11/19/2022]
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31
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Chen WM, Prell J, James EK, Sheu DS, Sheu SY. Effect of phosphoglycerate mutase and fructose 1,6-bisphosphatase deficiency on symbiotic Burkholderia phymatum. MICROBIOLOGY-SGM 2012; 158:1127-1136. [PMID: 22282515 DOI: 10.1099/mic.0.055095-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia phymatum STM815 is a β-rhizobial strain that can effectively nodulate several species of the large legume genus Mimosa. Two Tn5-induced mutants of this strain, KM16-22 and KM51, failed to form root nodules on Mimosa pudica, but still caused root hair deformation, which is one of the early steps of rhizobial infection. Both mutants grew well in a complex medium. However, KM16-22 could not grow on minimal medium unless a sugar and a metabolic intermediate such as pyruvate were provided, and KM51 also could not grow on minimal medium unless a sugar was added. The Tn5-interrupted genes of the mutants showed strong homologies to pgm, which encodes 2,3-biphosphoglycerate-dependent phosphoglycerate mutase (dPGM), and fbp, which encodes fructose 1,6-bisphosphatase (FBPase). Both enzymes are known to be involved in obligate steps in carbohydrate metabolism. Enzyme assays confirmed that KM16-22 and KM51 had indeed lost dPGM and FBPase activity, respectively, whilst the activities of these enzymes were expressed normally in both free-living bacteria and symbiotic bacteroids of the parental strain STM815. Both mutants recovered their enzyme activity after the introduction of wild-type pgm or fbp genes, were subsequently able to use carbohydrate as a carbon source, and were able to form root nodules on M. pudica and to fix nitrogen as efficiently as the parental strain. We conclude that the enzymes dPGM and FBPase are essential for the formation of a symbiosis with the host plant.
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Affiliation(s)
- Wen-Ming Chen
- Laboratory of Microbiology, Department of Seafood Science, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC
| | - Jurgen Prell
- Soil Ecology, Department of Botany, RWTH Aachen, 52056 Aachen, Germany
| | - Euan K James
- The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK
| | - Der-Shyan Sheu
- Department of Marine Biotechnology, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC
| | - Shih-Yi Sheu
- Department of Marine Biotechnology, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC
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32
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Aromatic compounds degradation plays a role in colonization of Arabidopsis thaliana and Acacia caven by Cupriavidus pinatubonensis JMP134. Antonie van Leeuwenhoek 2011; 101:713-23. [DOI: 10.1007/s10482-011-9685-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 12/08/2011] [Indexed: 10/14/2022]
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33
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Burch AY, Browne PJ, Dunlap CA, Price NP, Lindow SE. Comparison of biosurfactant detection methods reveals hydrophobic surfactants and contact-regulated production. Environ Microbiol 2011; 13:2681-91. [PMID: 21883788 DOI: 10.1111/j.1462-2920.2011.02534.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Biosurfactants are diverse molecules with numerous biological functions and industrial applications. A variety of environments were examined for biosurfactant-producing bacteria including soil, water and leaf surfaces. Biosurfactant production was assessed with an atomized oil assay for a large number of bacterial isolates and compared with a commonly used drop collapse assay from broth and plate cultures. The atomized oil assay detected every strain that produced a biosurfactant detectable by the drop collapse test, and also identified additional strains that were not detected with the drop collapse assay because they produced low levels of surfactant or hydrophobic (low water solubility) surfactants such as pumilacidins. Not all strains that produced a biosurfactant detectable by the drop collapse when cultured on agar surfaces produced surfactants detectable by drop collapse when cultured in broth, and vice versa. Many bacterial strains exhibited preferential production of surfactants when grown on an agar surface compared with broth cultures, and such surface enhancement of production could also be stimulated by increasing the viscosity of liquid culture media. Surface induction of surfactant production in the epiphyte Pseudomonas syringae was regulated at the transcriptional level.
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Affiliation(s)
- Adrien Y Burch
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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34
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Kim HS, Thammarat P, Lommel SA, Hogan CS, Charkowski AO. Pectobacterium carotovorum elicits plant cell death with DspE/F but the P. carotovorum DspE does not suppress callose or induce expression of plant genes early in plant-microbe interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:773-86. [PMID: 21469936 DOI: 10.1094/mpmi-06-10-0143] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The broad-host-range bacterial soft rot pathogen Pectobacterium carotovorum causes a DspE/F-dependent plant cell death on Nicotiana benthamiana within 24 h postinoculation (hpi) followed by leaf maceration within 48 hpi. P. carotovorum strains with mutations in type III secretion system (T3SS) regulatory and structural genes, including the dspE/F operon, did not cause hypersensitive response (HR)-like cell death and or leaf maceration. A strain with a mutation in the type II secretion system caused HR-like plant cell death but no maceration. P. carotovorum was unable to impede callose deposition in N. benthamiana leaves, suggesting that P. carotovorum does not suppress this basal immunity function. Within 24 hpi, there was callose deposition along leaf veins and examination showed that the pathogen cells were localized along the veins. To further examine HR-like plant cell death induced by P. carotovorum, gene expression profiles in N. benthamiana leaves inoculated with wild-type and mutant P. carotovorum and Pseudomonas syringae strains were compared. The N. benthamiana gene expression profile of leaves infiltrated with Pectobacterium carotovorum was similar to leaves infiltrated with a Pseudomonas syringae T3SS mutant. These data support a model where Pectobacterium carotovorum uses the T3SS to induce plant cell death in order to promote leaf maceration rather than to suppress plant immunity.
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Affiliation(s)
- Hye-Sook Kim
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
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35
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Uliczka F, Pisano F, Kochut A, Opitz W, Herbst K, Stolz T, Dersch P. Monitoring of gene expression in bacteria during infections using an adaptable set of bioluminescent, fluorescent and colorigenic fusion vectors. PLoS One 2011; 6:e20425. [PMID: 21673990 PMCID: PMC3108616 DOI: 10.1371/journal.pone.0020425] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 04/25/2011] [Indexed: 01/29/2023] Open
Abstract
A family of versatile promoter-probe plasmids for gene expression analysis was developed based on a modular expression plasmid system (pZ). The vectors contain different replicons with exchangeable antibiotic cassettes to allow compatibility and expression analysis on a low-, midi- and high-copy number basis. Suicide vector variants also permit chromosomal integration of the reporter fusion and stable vector derivatives can be used for in vivo or in situ expression studies under non-selective conditions. Transcriptional and translational fusions to the reporter genes gfpmut3.1, amCyan, dsRed2, luxCDABE, phoA or lacZ can be constructed, and presence of identical multiple cloning sites in the vector system facilitates the interchange of promoters or reporter genes between the plasmids of the series. The promoter of the constitutively expressed gapA gene of Escherichia coli was included to obtain fluorescent and bioluminescent expression constructs. A combination of the plasmids allows simultaneous detection and gene expression analysis in individual bacteria, e.g. in bacterial communities or during mouse infections. To test our vector system, we analyzed and quantified expression of Yersinia pseudotuberculosis virulence genes under laboratory conditions, in association with cells and during the infection process.
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Affiliation(s)
- Frank Uliczka
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany
- Department of Microbiology, Technical University Braunschweig, Braunschweig, Lower Saxony, Germany
| | - Fabio Pisano
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany
| | - Annika Kochut
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany
| | - Wiebke Opitz
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany
| | - Katharina Herbst
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany
| | - Tatjana Stolz
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Lower Saxony, Germany
- Department of Microbiology, Technical University Braunschweig, Braunschweig, Lower Saxony, Germany
- * E-mail:
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36
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Zhou D, Yang R. Formation and regulation of Yersinia biofilms. Protein Cell 2011; 2:173-9. [PMID: 21380640 DOI: 10.1007/s13238-011-1024-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Accepted: 02/18/2011] [Indexed: 12/31/2022] Open
Abstract
Flea-borne transmission is a recent evolutionary adaptation that distinguishes the deadly Yersinia pestis from its progenitor Y. Pseudotuberculosis, a mild pathogen transmitted via the food-borne route. Y. Pestis synthesizes biofilms in the flea gut, which is important for fleaborne transmission. Yersinia biofilms are bacterial colonies surrounded by extracellular matrix primarily containing a homopolymer of N-acetyl-D-glucosamine that are synthesized by a set of specific enzymes. Yersinia biofilm production is tightly regulated at both transcriptional and post-transcriptional levels. All the known structural genes responsible for biofilm production are harbored in both Y. Pseudotuberculosis and Y. Pestis, but Y. Pestis has evolved changes in the regulation of biofilm development, thereby acquiring efficient arthropod-borne transmission.
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Affiliation(s)
- Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China.
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37
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Marquez-Villavicencio MDP, Groves RL, Charkowski AO. Soft Rot Disease Severity Is Affected by Potato Physiology and Pectobacterium taxa. PLANT DISEASE 2011; 95:232-241. [PMID: 30743537 DOI: 10.1094/pdis-07-10-0526] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Pectobacterium species cause disease worldwide in many crop and ornamental plants, including potato. A new Pectobacterium subspecies, P. carotovorum subsp. brasiliensis was recently described in Brazil and later found in the United States, Israel, and South Africa. Its virulence traits and host range remain unknown. A comparison of three taxa commonly found on potato showed that both P. carotovorum subsp. carotovorum and subsp. brasiliensis are more aggressive in causing tuber and stem soft rot than P. atrosepticum. Also, despite bacterial growth inhibition in vitro of P. carotovorum subsp. carotovorum and P. atrosepticum strains by P. carotovorum subsp. brasiliensis, this new subspecies and P. carotovorum subsp. carotovorum are able to co-colonize in the same infected tissue. Both subspecies were motile in lesions. Pathogenesis assays showed that host ranges of all three overlap, but are not identical. The host ranges of individual strains of P. carotovorum subsp. carotovorum and subsp. brasiliensis are limited, whereas P. atrosepticum can macerate many plant species in addition to potato. There was high variability in virulence assays with potato tuber; thus physiological factors were investigated. Tuber size, maturity, and field location had significant effects on susceptibility to soft rot, with larger, more mature tubers being more susceptible.
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A non-invasive fluorescent staining procedure allows Confocal Laser Scanning Microscopy based imaging of Mycobacterium in multispecies biofilms colonizing and degrading polycyclic aromatic hydrocarbons. J Microbiol Methods 2010; 83:317-25. [DOI: 10.1016/j.mimet.2010.09.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 09/12/2010] [Accepted: 09/13/2010] [Indexed: 01/20/2023]
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Kimbrel JA, Givan SA, Halgren AB, Creason AL, Mills DI, Banowetz GM, Armstrong DJ, Chang JH. An improved, high-quality draft genome sequence of the Germination-Arrest Factor-producing Pseudomonas fluorescens WH6. BMC Genomics 2010; 11:522. [PMID: 20920191 PMCID: PMC2997014 DOI: 10.1186/1471-2164-11-522] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Accepted: 09/28/2010] [Indexed: 12/20/2022] Open
Abstract
Background Pseudomonas fluorescens is a genetically and physiologically diverse species of bacteria present in many habitats and in association with plants. This species of bacteria produces a large array of secondary metabolites with potential as natural products. P. fluorescens isolate WH6 produces Germination-Arrest Factor (GAF), a predicted small peptide or amino acid analog with herbicidal activity that specifically inhibits germination of seeds of graminaceous species. Results We used a hybrid next-generation sequencing approach to develop a high-quality draft genome sequence for P. fluorescens WH6. We employed automated, manual, and experimental methods to further improve the draft genome sequence. From this assembly of 6.27 megabases, we predicted 5876 genes, of which 3115 were core to P. fluorescens and 1567 were unique to WH6. Comparative genomic studies of WH6 revealed high similarity in synteny and orthology of genes with P. fluorescens SBW25. A phylogenomic study also placed WH6 in the same lineage as SBW25. In a previous non-saturating mutagenesis screen we identified two genes necessary for GAF activity in WH6. Mapping of their flanking sequences revealed genes that encode a candidate anti-sigma factor and an aminotransferase. Finally, we discovered several candidate virulence and host-association mechanisms, one of which appears to be a complete type III secretion system. Conclusions The improved high-quality draft genome sequence of WH6 contributes towards resolving the P. fluorescens species, providing additional impetus for establishing two separate lineages in P. fluorescens. Despite the high levels of orthology and synteny to SBW25, WH6 still had a substantial number of unique genes and represents another source for the discovery of genes with implications in affecting plant growth and health. Two genes are demonstrably necessary for GAF and further characterization of their proteins is important for developing natural products as control measure against grassy weeds. Finally, WH6 is the first isolate of P. fluorescens reported to encode a complete T3SS. This gives us the opportunity to explore the role of what has traditionally been thought of as a virulence mechanism for non-pathogenic interactions with plants.
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Affiliation(s)
- Jeffrey A Kimbrel
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
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Genome-driven investigation of compatible solute biosynthesis pathways of Pseudomonas syringae pv. syringae and their contribution to water stress tolerance. Appl Environ Microbiol 2010; 76:5452-62. [PMID: 20581190 DOI: 10.1128/aem.00686-10] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The foliar pathogen Pseudomonas syringae pv. syringae exhibits an exceptional ability to survive on asymptomatic plants as an epiphyte. Intermittent wetting events on plants lead to osmotic and matric stresses which must be tolerated for survival as an epiphyte. In this study, we have applied bioinformatic, genetic, and biochemical approaches to address water stress tolerance in P. syringae pv. syringae strain B728a, for which a complete genome sequence is available. P. syringae pv. syringae B728a is able to produce the compatible solutes betaine, ectoine, N-acetylglutaminylglutamine amide (NAGGN), and trehalose. Analysis of osmolyte profiles of P. syringae pv. syringae B728a under a variety of in vitro and in planta conditions reveals that the osmolytes differentially contribute to water stress tolerance in this species and that they interact at the level of transcription to yield a hierarchy of expression. While the interruption of a putative gene cluster coding for NAGGN biosynthesis provided the first experimental evidence of the NAGGN biosynthetic pathway, application of this knockout strain and also a gfp reporter gene fusion strain demonstrated the small contribution of NAGGN to cell survival and desiccation tolerance of P. syringae pv. syringae B728a under in planta conditions. Additionally, detailed investigation of ectC, an orphan of the ectoine cluster (lacking the ectA and ectB homologs), revealed its functionality and that ectoine production could be detected in NaCl-amended cultures of P. syringae pv. syringae B728a to which sterilized leaves of Syringa vulgaris had been added.
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Pseudomonas aeruginosa-mediated damage requires distinct receptors at the apical and basolateral surfaces of the polarized epithelium. Infect Immun 2009; 78:939-53. [PMID: 20008530 DOI: 10.1128/iai.01215-09] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Pseudomonas aeruginosa, an important opportunistic pathogen of humans, exploits epithelial damage to establish infection. We have rigorously explored the role of N-glycoproteins and heparan sulfate proteoglycans (HSPGs) in P. aeruginosa-mediated attachment and subsequent downstream events at the apical (AP) and basolateral (BL) surfaces of polarized epithelium. We demonstrate that the N-glycan chains at the AP surface are necessary and sufficient for binding, invasion, and cytotoxicity to kidney (MDCK) and airway (Calu-3) cells grown at various states of polarization on Transwell filters. Upregulation of N-glycosylation enhanced binding, whereas pharmacologic inhibition of N-glycosylation or infection of MDCK cells defective in N-glycosylation resulted in decreased binding. In contrast, at the BL surface, the HS moiety of HSPGs mediated P. aeruginosa binding, cytotoxicity, and invasion. In incompletely polarized epithelium, HSPG abundance was increased at the AP surface, explaining its increased susceptibility to P. aeruginosa colonization and damage. Using MDCK cells grown as three-dimensional cysts as a model for epithelial organs, we show that P. aeruginosa specifically colocalized with HS-rich areas at the BL membrane but with complex N-glycans at the AP surface. Finally, P. aeruginosa bound to HS chains and N-glycans coated on plastic surfaces, showing the highest binding affinity toward isolated HS chains. Together, these findings demonstrate that P. aeruginosa recognizes distinct receptors on the AP and BL surfaces of polarized epithelium. Changes in the composition of N-glycan chains and/or in the distribution of HSPGs may explain the enhanced susceptibility of damaged epithelium to P. aeruginosa.
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Chungjatupornchai W, Fa-aroonsawat S. Translocation of green fluorescent protein to cyanobacterial periplasm using ice nucleation protein. J Microbiol 2009; 47:187-92. [PMID: 19412603 DOI: 10.1007/s12275-008-0188-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 12/07/2008] [Indexed: 10/20/2022]
Abstract
The translocation of proteins to cyanobacterial cell envelope is made complex by the presence of a highly differentiated membrane system. To investigate the protein translocation in cyanobacterium Synechococcus PCC 7942 using the truncated ice nucleation protein (InpNC) from Pseudomonas syringae KCTC 1832, the green fluorescent protein (GFP) was fused in frame to the carboxyl-terminus of InpNC. The fluorescence of GFP was found almost entirely as a halo in the outer regions of cells which appeared to correspond to the periplasm as demonstrated by confocal laser scanning microscopy, however, GFP was not displayed on the outermost cell surface. Western blotting analysis revealed that InpNC-GFP fusion protein was partially degraded. The N-terminal domain of InpNC may be susceptible to protease attack; the remaining C-terminal domain conjugated with GFP lost the ability to direct translocation across outer membrane and to act as a surface display motif. The fluorescence intensity of cells with periplasmic GFP was approximately 6-fold lower than that of cells with cytoplasmic GFP. The successful translocation of the active GFP to the periplasm may provide a potential means to study the property of cyanobacterial periplasmic substances in response to environmental changes in a non-invasive manner.
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Affiliation(s)
- Wipa Chungjatupornchai
- Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom, 73170, Thailand.
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Thammachat S, Pathaichindachote W, Krittanai C, Promdonkoy B. Amino acids at N- and C-termini are required for the efficient production and folding of a cytolytic delta-endotoxin from Bacillus thuringiensis. BMB Rep 2009; 41:820-5. [PMID: 19017496 DOI: 10.5483/bmbrep.2008.41.11.820] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus thuringiensis Cyt2Aa toxin is a mosquito-larvicidal and cytolytic delta-endotoxin, which is synthesized as a protoxin and forms crystalline inclusions within the cell. These inclusions are solubilized under alkaline conditions and are activated by proteases within the larval gut. In order to assess the functions of the N-and C-terminal regions of the protoxin, several N- and C-terminal truncated forms of Cyt2Aa were constructed. It was determined that amino acid removal at the N-terminal, which disrupts the beta1 structure, might critically influence toxin production and inclusion formation. The deletion of 22 amino acids from the C-terminus reduced the production and solubility of the toxin. However, the removal of more than 22 amino acids from the C-terminus or the addition of a bulky group to this region could result in the inability of the protein to adopt the proper folding. These findings directly demonstrated the critical roles of N- and C- terminal amino acids on the production and folding of the B. thuringiensis cytolytic delta-endotoxin.
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Affiliation(s)
- Siriya Thammachat
- Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakhonpathom, Thailand
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Involvement of Shewanella oneidensis MR-1 LuxS in biofilm development and sulfur metabolism. Appl Environ Microbiol 2009; 75:1301-7. [PMID: 19124589 DOI: 10.1128/aem.01393-08] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The role of LuxS in Shewanella oneidensis MR-1 has been examined by transcriptomic profiling, biochemical, and physiological experiments. The results indicate that a mutation in luxS alters biofilm development, not by altering quorum-sensing abilities but by disrupting the activated methyl cycle (AMC). The S. oneidensis wild type can produce a luminescence response in the AI-2 reporter strain Vibrio harveyi MM32. This luminescence response is abolished upon the deletion of luxS. The deletion of luxS also alters biofilm formations in static and flowthrough conditions. Genetic complementation restores the mutant biofilm defect, but the addition of synthetic AI-2 has no effect. These results suggest that AI-2 is not used as a quorum-sensing signal to regulate biofilm development in S. oneidensis. Growth on various sulfur sources was examined because of the involvement of LuxS in the AMC. A mutation in luxS produced a reduced ability to grow with methionine as the sole sulfur source. Methionine is a key metabolite used in the AMC to produce a methyl source in the cell and to recycle homocysteine. These data suggest that LuxS is important to metabolizing methionine and the AMC in S. oneidensis.
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Two dissimilar N-acyl-homoserine lactone acylases of Pseudomonas syringae influence colony and biofilm morphology. Appl Environ Microbiol 2008; 75:45-53. [PMID: 18997027 DOI: 10.1128/aem.01723-08] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Plant aerial surfaces comprise a complex habitat for microorganisms, and many plant-associated bacteria, such as the pathogen Pseudomonas syringae, exhibit density-dependent survival on leaves by utilizing quorum sensing (QS). QS is often mediated by diffusible signals called N-acyl-homoserine lactones (AHLs), and P. syringae utilizes N-3-oxo-hexanoyl-dl-homoserine lactone (3OC6HSL) to control traits influencing epiphytic fitness and virulence. The P. syringae pathovar syringae B728a genome sequence revealed two putative AHL acylases, termed HacA (Psyr_1971) and HacB (Psyr_4858), which are N-terminal nucleophile hydrolases that inactivate AHLs by cleaving their amide bonds. HacA is a secreted AHL acylase that degrades only long-chain (C > or = 8) AHLs, while HacB is not secreted and degrades all tested AHLs. Targeted disruptions of hacA, hacB, and hacA and hacB together do not alter endogenous 3OC6HSL levels under the tested conditions. Surprisingly, targeted disruptions of hacA alone and hacA and hacB together confer complementable phenotypes that are very similar to autoaggregative phenotypes seen in other species. While AHL acylases might enable P. syringae B728a to degrade signals of competing species and block expression of their QS-dependent traits, these enzymes also play fundamental roles in biofilm formation.
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Dandie C, Thomas S, McClure N. Comparison of a range of green fluorescent protein-tagging vectors for monitoring a microbial inoculant in soil. Lett Appl Microbiol 2008. [DOI: 10.1111/j.1472-765x.2001.00848.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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McLean JS, Majors PD, Reardon CL, Bilskis CL, Reed SB, Romine MF, Fredrickson JK. Investigations of structure and metabolism within Shewanella oneidensis MR-1 biofilms. J Microbiol Methods 2008; 74:47-56. [DOI: 10.1016/j.mimet.2008.02.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Accepted: 02/18/2008] [Indexed: 11/26/2022]
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Proteomic, microarray, and signature-tagged mutagenesis analyses of anaerobic Pseudomonas aeruginosa at pH 6.5, likely representing chronic, late-stage cystic fibrosis airway conditions. J Bacteriol 2008; 190:2739-58. [PMID: 18203836 DOI: 10.1128/jb.01683-07] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Patients suffering from cystic fibrosis (CF) commonly harbor the important pathogen Pseudomonas aeruginosa in their airways. During chronic late-stage CF, P. aeruginosa is known to grow under reduced oxygen tension and is even capable of respiring anaerobically within the thickened airway mucus, at a pH of approximately 6.5. Therefore, proteins involved in anaerobic metabolism represent potentially important targets for therapeutic intervention. In this study, the clinically relevant "anaerobiome" or "proteogenome" of P. aeruginosa was assessed. First, two different proteomic approaches were used to identify proteins differentially expressed under anaerobic versus aerobic conditions. Microarray studies were also performed, and in general, the anaerobic transcriptome was in agreement with the proteomic results. However, we found that a major portion of the most upregulated genes in the presence of NO(3)(-) and NO(2)(-) are those encoding Pf1 bacteriophage. With anaerobic NO(2)(-), the most downregulated genes are those involved postglycolytically and include many tricarboxylic acid cycle genes and those involved in the electron transport chain, especially those encoding the NADH dehydrogenase I complex. Finally, a signature-tagged mutagenesis library of P. aeruginosa was constructed to further screen genes required for both NO(3)(-) and NO(2)(-) respiration. In addition to genes anticipated to play important roles in the anaerobiome (anr, dnr, nar, nir, and nuo), the cysG and dksA genes were found to be required for both anaerobic NO(3)(-) and NO(2)(-) respiration. This study represents a major step in unraveling the molecular machinery involved in anaerobic NO(3)(-) and NO(2)(-) respiration and offers clues as to how we might disrupt such pathways in P. aeruginosa to limit the growth of this important CF pathogen when it is either limited or completely restricted in its oxygen supply.
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Sanschagrin F, Kukavica-Ibrulj I, Levesque RC. Essential genes in the infection model of Pseudomonas aeruginosa PCR-based signature-tagged mutagenesis. Methods Mol Biol 2008; 416:61-82. [PMID: 18392961 DOI: 10.1007/978-1-59745-321-9_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
PCR-based signature tagged mutagenesis is an "en masse" screening technique based upon unique oligonucleotide tags (molecular barcodes) for identification of genes that will diminish or enhance maintenance of an organism in a specific ecological niche or environment. PCR-based STM applied to Pseudomonas aeruginosa permitted the identification of genes essential or in vivo maintenance by transposon insertion and negative selection in a mixed population of bacterial mutants. The innovative adaptations and refinement of the technology presented here with P. aeruginosa STM mutants selected in the rat lung have given critical information about genes essential for causing a chronic infection and a wealth of information about biological processes in vivo. The additional use of competitive index analysis for measurement of the level of virulence in vivo, microarray-based screening of selected prioritized STM mutants coupled to metabolomics analysis can now be attempted systematically on a genomic scale. PCR-based STM and combined whole-genome methods can also be applied to any organism having selectable phenotypes for screening.
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Affiliation(s)
- François Sanschagrin
- Centre de Recherche sur la Fonction, Structure et Ingénierie des Protéines (CREFSIP), Pavillon Charles-Eugène Marchand, Biologie Médicale, Faculté de Médecine, Université Laval, Québec, Canada
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McLean JS, Ona ON, Majors PD. Correlated biofilm imaging, transport and metabolism measurements via combined nuclear magnetic resonance and confocal microscopy. ISME JOURNAL 2007; 2:121-31. [PMID: 18253132 DOI: 10.1038/ismej.2007.107] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Bacterial biofilms are complex, three-dimensional communities found nearly everywhere in nature and are also associated with many human diseases. Detailed metabolic information is critical to understand and exploit beneficial biofilms as well as combat antibiotic-resistant, disease-associated forms. However, most current techniques used to measure temporal and spatial metabolite profiles in these delicate structures are invasive or destructive. Here, we describe imaging, transport and metabolite measurement methods and their correlation for live, non-invasive monitoring of biofilm processes. This novel combination of measurements is enabled by the use of an integrated nuclear magnetic resonance (NMR) and confocal laser scanning microscope (CLSM). NMR methods provide macroscopic structure, metabolic pathway and rate data, spatially resolved metabolite concentrations and water diffusion profiles within the biofilm. In particular, current depth-resolved spectroscopy methods are applied to detect metabolites in 140-190 nl volumes within biofilms of the dissimilatory metal-reducing bacterium Shewanella oneidensis strain MR-1 and the oral bacterium implicated in caries disease, Streptococcus mutans strain UA159. The perfused sample chamber also contains a transparent optical window allowing for the collection of complementary fluorescence information using a unique, in-magnet CLSM. In this example, the entire three-dimensional biofilm structure was imaged using magnetic resonance imaging. This was then correlated to a fluorescent CLSM image by employing a green fluorescent protein reporter construct of S. oneidensis. Non-invasive techniques such as described here, which enable measurements of dynamic metabolic processes, especially in a depth-resolved fashion, are expected to advance our understanding of processes occurring within biofilm communities.
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Affiliation(s)
- Jeffrey S McLean
- Environmental Microbial Genomics, J. Craig Venter Institute, 111 49 N Torrey Pines Rd, Suite 220, La Jolla, CA 92037, USA.
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