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Pitton M, Valente LG, Oberhaensli S, Casanova C, Sendi P, Schnegg B, Jakob SM, Cameron DR, Que YA, Fürholz M. Dynamics of bacterial pathogens at the driveline exit site in patients with ventricular assist devices: A prospective, observational, single-center cohort study. J Heart Lung Transplant 2023; 42:1445-1454. [PMID: 37245557 DOI: 10.1016/j.healun.2023.05.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/30/2023] [Accepted: 05/24/2023] [Indexed: 05/30/2023] Open
Abstract
BACKGROUND Driveline infections (DLIs) at the exit site are frequent in patients with left ventricular assist devices (LVADs). The dynamics from colonization to infection are yet to be investigated. We combined systematic swabbing at the driveline exit site and genomic analyses to study the dynamics of bacterial pathogens and get insights into DLIs pathogenesis. METHODS A prospective, observational, single-center cohort study at the University Hospital of Bern, Switzerland was performed. Patients with LVAD were systematically swabbed at the driveline exit site between June 2019 and December 2021, irrespective of signs and symptoms of DLI. Bacterial isolates were identified and a subset was whole-genome sequenced. RESULTS Fifty-three patients were screened, of which 45 (84.9%) were included in the final population. Bacterial colonization at the driveline exit site without manifestation of DLI was frequent and observed in 17 patients (37.8%). Twenty-two patients (48.9%) developed at least one DLI episode over the study period. Incidence of DLIs reached 2.3 cases per 1000 LVAD days. The majority of the organisms cultivated from exit sites were Staphylococcus species. Genome analysis revealed that bacteria persisted at the driveline exit site over time. In four patients, transition from colonization to clinical DLI was observed. CONCLUSIONS Our study is the first to address bacterial colonization in the LVAD-DLI setting. We observed that bacterial colonization at the driveline exit site was a frequent phenomenon, and in a few cases, it preceded clinically relevant infections. We also provided acquisition of hospital-acquired multidrug-resistant bacteria and the transmission of pathogens between patients.
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Affiliation(s)
- Melissa Pitton
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Bern, Switzerland
| | - Luca G Valente
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Bern, Switzerland; Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit, University of Bern, Bern, Switzerland; SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Carlo Casanova
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Parham Sendi
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Bruno Schnegg
- Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stephan M Jakob
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - David R Cameron
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Yok-Ai Que
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Monika Fürholz
- Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
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2
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Dainat B, Oberhaensli S, Ory F, Dietemann V. New reference genomes of honey bee-associated bacteria Paenibacillus melissococcoides, Paenibacillus dendritiformis, and Paenibacillus thiaminolyticus. Microbiol Resour Announc 2023; 12:e0020923. [PMID: 37530538 PMCID: PMC10508097 DOI: 10.1128/mra.00209-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/18/2023] [Indexed: 08/03/2023] Open
Abstract
We sequenced the genomes of recently discovered Paenibacillus melissococcoides (CCOS 2000) and of the type strains of closely related P. thiaminolyticus (DSM 7262) and P. dendritiformis (LMG 21716). The three genomes set the basis to unambiguous diagnostic of these honey bee associated Paenibacillus bacteria.
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Affiliation(s)
- Benjamin Dainat
- Swiss Bee Research Center, Agroscope Liebefeld, Bern, Switzerland
| | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
| | - Florine Ory
- Swiss Bee Research Center, Agroscope Liebefeld, Bern, Switzerland
| | - Vincent Dietemann
- Swiss Bee Research Center, Agroscope Liebefeld, Bern, Switzerland
- Department of Ecology and Evolution, Biophore, UNIL-Sorge, University of Lausanne, Lausanne, Switzerland
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Ory F, Dietemann V, Guisolan A, von Ah U, Fleuti C, Oberhaensli S, Charrière JD, Dainat B. Paenibacillus melissococcoides sp. nov., isolated from a honey bee colony affected by European foulbrood disease. Int J Syst Evol Microbiol 2023; 73. [PMID: 37185226 DOI: 10.1099/ijsem.0.005829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
A novel, facultatively anaerobic, Gram-stain-positive, motile, endospore-forming bacterium of the genus
Paenibacillus
, designated strain 2.1T, was isolated from a colony of Apis mellifera affected by European foulbrood disease in Switzerland. The rod-shaped cells of strain 2.1T were 2.2–6.5 µm long and 0.7–1.1 µm wide. Colonies of strain 2.1T were orange-pigmented under oxic growth conditions on solid basal medium at 35–37 °C. Strain 2.1T showed catalase and cytochrome c oxidase activity. Its polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, aminophospholipid and phospholipid. The only respiratory quinone was menaquinone 7, and the major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, iso-C17 : 0 and palmitic acid (C16 : 0), which is consistent with other members of the genus
Paenibacillus
. The G+C content of the genomic DNA of strain 2.1T was 53.3 mol%. Phylogenetic analyses based on the 16S rRNA gene sequence similarity showed that strain 2.1T was closely related to
Paenibacillus dendritiformis
LMG 21716T (99.7 % similarity) and
Paenibacillus thiaminolyticus
DSM 7262T (98.8 %). The whole-genome average nucleotide identity between strain 2.1T and the type strains of
P. dendritiformis
and
P. thiaminolyticus
was 92 and 91 %, respectively, and thus lower than the 95 % threshold value for delineation of genomic prokaryotic species. Based on the results of phylogenetic, genomic, phenotypic and chemotaxonomic analyses we propose the name Paenibacillus melissococcoides sp. nov. for this novel
Paenibacillus
species. The type strain is 2.1T (=CCOS 2000T=DSM 113619T=LMG 32539T).
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Affiliation(s)
- Florine Ory
- Swiss Bee Research Centre, Agroscope, Bern, Switzerland
| | - Vincent Dietemann
- Swiss Bee Research Centre, Agroscope, Bern, Switzerland
- Department Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Anne Guisolan
- Biotechnology Research Group, Agroscope, Bern, Switzerland
| | - Ueli von Ah
- Biotechnology Research Group, Agroscope, Bern, Switzerland
| | | | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
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Cameron DR, Pitton M, Oberhaensli S, Schlegel K, Prod’hom G, Blanc DS, Jakob SM, Que YA. Parallel Evolution of Pseudomonas aeruginosa during a Prolonged ICU-Infection Outbreak. Microbiol Spectr 2022; 10:e0274322. [PMID: 36342287 PMCID: PMC9769503 DOI: 10.1128/spectrum.02743-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/19/2022] [Indexed: 11/09/2022] Open
Abstract
Most knowledge about Pseudomonas aeruginosa pathoadaptation is derived from studies on airway colonization in cystic fibrosis; little is known about adaptation in acute settings. P. aeruginosa frequently affects burned patients and the burn wound niche has distinct properties that likely influence pathoadaptation. This study aimed to genetically and phenotypically characterize P. aeruginosa isolates collected during an outbreak of infection in a burn intensive care unit (ICU). Sequencing reads from 58 isolates of ST1076 P. aeruginosa taken from 23 patients were independently mapped to a complete reference genome for the lineage (H25338); genetic differences were identified and were used to define the population structure. Comparative genomic analysis at single-nucleotide resolution identified pathoadaptive genes that evolved multiple, independent mutations. Three key phenotypic assays (growth performance, motility, carbapenem resistance) were performed to complement the genetic analysis for 47 unique isolates. Population structure for the ST1076 lineage revealed 11 evolutionary sublineages. Fifteen pathoadaptive genes evolved mutations in at least two sublineages. The most prominent functional classes affected were transcription/two-component regulatory systems, and chemotaxis/motility and attachment. The most frequently mutated gene was oprD, which codes for outer membrane porin involved in uptake of carbapenems. Reduced growth performance and motility were found to be adaptive phenotypic traits, as was high level of carbapenem resistance, which correlated with higher carbapenem consumption during the outbreak. Multiple prominent linages evolved each of the three traits in parallel providing evidence that they afford a fitness advantage for P. aeruginosa in the context of human burn infection. IMPORTANCE Pseudomonas aeruginosa is a Gram-negative pathogen causing infections in acutely burned patients. The precise mechanisms required for the establishment of infection in the burn setting, and adaptive traits underpinning prolonged outbreaks are not known. We have assessed genotypic data from 58 independent P. aeruginosa isolates taken from a single lineage that was responsible for an outbreak of infection in a burn ICU that lasted for almost 2.5 years and affected 23 patients. We identified a core set of 15 genes that we predict to control pathoadaptive traits in the burn infection based on the frequency with which independent mutations evolved. We combined the genotypic data with phenotypic data (growth performance, motility, antibiotic resistance) and clinical data (antibiotic consumption) to identify adaptive phenotypes that emerged in parallel. High-level carbapenem resistance evolved rapidly, and frequently, in response to high clinical demand for this antibiotic class during the outbreak.
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Affiliation(s)
- David R. Cameron
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Melissa Pitton
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences (GCB), University of Bern, Bern, Switzerland
| | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
| | - Katja Schlegel
- Institute of Psychology, University of Bern, Bern, Switzerland
| | - Guy Prod’hom
- Institute of Microbiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Dominique S. Blanc
- Service of Hospital Preventive Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Stephan M. Jakob
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Yok-Ai Que
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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5
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Turgay M, Falentin H, Irmler S, Fröhlich-Wyder MT, Meola M, Oberhaensli S, Berthoud-dit-Gallon Marchand H. Genomic rearrangements in the aspA-dcuA locus of Propionibacterium freudenreichii are associated with aspartase activity. Food Microbiol 2022; 106:104030. [DOI: 10.1016/j.fm.2022.104030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 02/02/2022] [Accepted: 03/20/2022] [Indexed: 11/25/2022]
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Dorn P, Pfister S, Oberhaensli S, Gioutsos K, Haenggi M, Kocher GJ. OUP accepted manuscript. Interact Cardiovasc Thorac Surg 2022; 34:768-774. [PMID: 35134941 PMCID: PMC9070522 DOI: 10.1093/icvts/ivac023] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 01/02/2022] [Indexed: 11/24/2022] Open
Affiliation(s)
- Patrick Dorn
- Department of Thoracic Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Corresponding author. Department of Thoracic Surgery, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse, 3010 Bern, Switzerland. Tel: +41-31-6323489; e-mail: (P. Dorn)
| | - Selina Pfister
- Department of Thoracic Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
| | - Konstantinos Gioutsos
- Department of Thoracic Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Matthias Haenggi
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Gregor J Kocher
- Department of Thoracic Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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7
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Shani N, Oberhaensli S, Berthoud H, Schmidt RS, Bachmann HP. Antimicrobial Susceptibility of Lactobacillus delbrueckii subsp. lactis from Milk Products and Other Habitats. Foods 2021; 10:foods10123145. [PMID: 34945696 PMCID: PMC8701367 DOI: 10.3390/foods10123145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 11/16/2022] Open
Abstract
As components of many cheese starter cultures, strains of Lactobacillus delbrueckii subsp. lactis (LDL) must be tested for their antimicrobial susceptibility to avoid the potential horizontal transfer of antibiotic resistance (ABR) determinants in the human body or in the environment. To this end, a phenotypic test, as well as a screening for antibiotic resistance genes (ARGs) in genome sequences, is commonly performed. Historically, microbiological cutoffs (MCs), which are used to classify strains as either 'sensitive' or 'resistant' based on the minimal inhibitory concentrations (MICs) of a range of clinically-relevant antibiotics, have been defined for the whole group of the obligate homofermentative lactobacilli, which includes LDL among many other species. This often leads to inaccuracies in the appreciation of the ABR status of tested LDL strains and to false positive results. To define more accurate MCs for LDL, we analyzed the MIC profiles of strains originating from various habitats by using the broth microdilution method. These strains' genomes were sequenced and used to complement our analysis involving a search for ARGs, as well as to assess the phylogenetic proximity between strains. Of LDL strains, 52.1% displayed MICs that were higher than the defined MCs for kanamycin, 9.9% for chloramphenicol, and 5.6% for tetracycline, but no ARG was conclusively detected. On the other hand, all strains displayed MICs below the defined MCs for ampicillin, gentamycin, erythromycin, and clindamycin. Considering our results, we propose the adaptation of the MCs for six of the tested clinically-relevant antibiotics to improve the accuracy of phenotypic antibiotic testing.
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Affiliation(s)
- Noam Shani
- Competence Division Methods Development and Analytics, Agroscope, Schwarzenburgstrasse 161, 3003 Bern, Switzerland;
- Correspondence:
| | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland;
| | - Hélène Berthoud
- Competence Division Methods Development and Analytics, Agroscope, Schwarzenburgstrasse 161, 3003 Bern, Switzerland;
| | - Remo S. Schmidt
- Research Division Food Microbial Systems, Agroscope, Schwarzenburgstrasse 161, 3003 Bern, Switzerland; (R.S.S.); (H.-P.B.)
| | - Hans-Peter Bachmann
- Research Division Food Microbial Systems, Agroscope, Schwarzenburgstrasse 161, 3003 Bern, Switzerland; (R.S.S.); (H.-P.B.)
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8
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Shani N, Oberhaensli S, Arias-Roth E. Antibiotic Susceptibility Profiles of Pediococcus pentosaceus from Various Origins and Their Implications for the Safety Assessment of Strains with Food-Technology Applications. J Food Prot 2021; 84:1160-1168. [PMID: 33320937 DOI: 10.4315/jfp-20-363] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 12/11/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT In the fight against the spread of antibiotic resistance, authorities usually require that strains "intentionally added into the food chain" be tested for their antibiotic susceptibility. This applies to strains used in starter or adjunct cultures for the production of fermented foods, such as many strains of Pediococcus pentosaceus. The European Food Safety Authority recommends testing strains for their antibiotic susceptibility based on both genomic and phenotypic approaches. Furthermore, it proposes a set of antibiotics to assess as well as a list of microbiological cutoffs (MCs), allowing classification of lactic acid bacteria as susceptible or resistant. Accurate MCs are essential not only to avoid false-negative strains, which may carry antibiotic resistance genes and remain unnoticed, but also to avoid false-positive strains, which may be discarded while screening potential candidates for food-technology applications. Because of relatively scarce data, MCs have been defined for the whole Pediococcus genus, although differences between species should be expected. In this study, we investigated the antibiotic susceptibility of 35 strains of P. pentosaceus isolated from various matrices in the past 70 yr. MICs were determined using a standard protocol, and MIC distributions were established. Phenotypic analyses were complemented with genome sequencing and by seeking known antibiotic resistance genes. The genomes of all the strains were free of known antibiotic resistance genes, but most displayed MICs above the currently defined MCs for chloramphenicol, and all showed excessive MICs for tetracycline. Based on the distributions, we calculated and proposed new MCs for chloramphenicol (16 instead of 4 mg/L) and tetracycline (256 instead of 8 mg/L). HIGHLIGHTS
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Affiliation(s)
- Noam Shani
- Competence Division Method Development and Analytics, University of Bern, 3012 Bern, Switzerland.,(ORCID: https://orcid.org/0000-0002-3570-9947 [N.S.])
| | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, 3012 Bern, Switzerland
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9
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Valente LG, Pitton M, Fürholz M, Oberhaensli S, Bruggmann R, Leib SL, Jakob SM, Resch G, Que YA, Cameron DR. Isolation and characterization of bacteriophages from the human skin microbiome that infect Staphylococcus epidermidis. FEMS Microbes 2021; 2:xtab003. [PMID: 37334235 PMCID: PMC10117716 DOI: 10.1093/femsmc/xtab003] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/26/2021] [Indexed: 07/20/2023] Open
Abstract
Phage therapy might be a useful approach for the treatment of nosocomial infections; however, only few lytic phages suitable for this application are available for the opportunistic pathogen, Staphylococcus epidermidis. In the current study, we developed an efficient method to isolate bacteriophages present within the human skin microbiome, by using niche-specific S. epidermidis as the host for phage propagation. Staphylococcus epidermidis was identified on the forehead of 92% of human subjects tested. These isolates were then used to propagate phages present in the same skin sample. Plaques were observable on bacterial lawns in 46% of the cases where S. epidermidis was isolated. A total of eight phage genomes were genetically characterized, including the previously described phage 456. A total of six phage sequences were unique, and spanned each of the major staphylococcal phage families; Siphoviridae (n = 3), Podoviridae (n = 1) and Myoviridae (n = 2). One of the myoviruses (vB_SepM_BE06) was identified on the skin of three different humans. Comparative analysis identified novel genes including a putative N-acetylmuramoyl-L-alanine amidase gene. The host-range of each unique phage was characterized using a panel of diverse staphylococcal strains (n = 78). None of the newly isolated phages infected more than 52% of the S. epidermidis strains tested (n = 44), and non-S. epidermidis strains where rarely infected, highlighting the narrow host-range of the phages. One of the phages (vB_SepM_BE04) was capable of killing staphylococcal cells within biofilms formed on polyurethane catheters. Uncovering a richer diversity of available phages will likely improve our understanding of S. epidermidis-phage interactions, which will be important for future therapy.
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Affiliation(s)
| | | | - Monika Fürholz
- Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Simone Oberhaensli
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
| | - Rémy Bruggmann
- Interfaculty Bioinformatics Unit and SIB Swiss Institute of Bioinformatics, University of Bern, Bern, Switzerland
| | - Stephen L Leib
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Stephan M Jakob
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Grégory Resch
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Yok-Ai Que
- Department of Intensive Care Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - David R Cameron
- Corresponding author: Department of Intensive Care Medicine, Inselspital; Bern University Hospital, 3010 Bern, Switzerland. Tel: +41 31 632 42 55; E-mail:
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10
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Dylus D, Pillonel T, Opota O, Wüthrich D, Seth-Smith HMB, Egli A, Leo S, Lazarevic V, Schrenzel J, Laurent S, Bertelli C, Blanc DS, Neuenschwander S, Ramette A, Falquet L, Imkamp F, Keller PM, Kahles A, Oberhaensli S, Barbié V, Dessimoz C, Greub G, Lebrand A. NGS-Based S. aureus Typing and Outbreak Analysis in Clinical Microbiology Laboratories: Lessons Learned From a Swiss-Wide Proficiency Test. Front Microbiol 2020; 11:591093. [PMID: 33424794 PMCID: PMC7793906 DOI: 10.3389/fmicb.2020.591093] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/19/2020] [Indexed: 12/31/2022] Open
Abstract
Whole genome sequencing (WGS) enables high resolution typing of bacteria up to the single nucleotide polymorphism (SNP) level. WGS is used in clinical microbiology laboratories for infection control, molecular surveillance and outbreak analyses. Given the large palette of WGS reagents and bioinformatics tools, the Swiss clinical bacteriology community decided to conduct a ring trial (RT) to foster harmonization of NGS-based bacterial typing. The RT aimed at assessing methicillin-susceptible Staphylococcus aureus strain relatedness from WGS and epidemiological data. The RT was designed to disentangle the variability arising from differences in sample preparation, SNP calling and phylogenetic methods. Nine laboratories participated. The resulting phylogenetic tree and cluster identification were highly reproducible across the laboratories. Cluster interpretation was, however, more laboratory dependent, suggesting that an increased sharing of expertise across laboratories would contribute to further harmonization of practices. More detailed bioinformatic analyses unveiled that while similar clusters were found across laboratories, these were actually based on different sets of SNPs, differentially retained after sample preparation and SNP calling procedures. Despite this, the observed number of SNP differences between pairs of strains, an important criterion to determine strain relatedness given epidemiological information, was similar across pipelines for closely related strains when restricting SNP calls to a common core genome defined by S. aureus cgMLST schema. The lessons learned from this pilot study will serve the implementation of larger-scale RT, as a mean to have regular external quality assessments for laboratories performing WGS analyses in a clinical setting.
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Affiliation(s)
- David Dylus
- Department of Computational Biology, University of Lausanne, Lausanne, Switzerland.,Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Trestan Pillonel
- Institute of Microbiology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Onya Opota
- Institute of Microbiology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Daniel Wüthrich
- Division of Clinical Bacteriology and Mycology, University Hospital of Basel, Basel, Switzerland.,Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Helena M B Seth-Smith
- Division of Clinical Bacteriology and Mycology, University Hospital of Basel, Basel, Switzerland.,Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Adrian Egli
- Division of Clinical Bacteriology and Mycology, University Hospital of Basel, Basel, Switzerland.,Applied Microbiology Research, Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Stefano Leo
- Bacteriology Laboratory, Division of Laboratory Medicine, Department of Genetics Laboratory Medicine and Pathology, Geneva University Hospitals, Geneva, Switzerland
| | - Vladimir Lazarevic
- Bacteriology Laboratory, Division of Laboratory Medicine, Department of Genetics Laboratory Medicine and Pathology, Geneva University Hospitals, Geneva, Switzerland
| | - Jacques Schrenzel
- Bacteriology Laboratory, Division of Laboratory Medicine, Department of Genetics Laboratory Medicine and Pathology, Geneva University Hospitals, Geneva, Switzerland
| | - Sacha Laurent
- Institute of Microbiology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Claire Bertelli
- Institute of Microbiology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Dominique S Blanc
- Service of Hospital Preventive Medicine, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | | | - Alban Ramette
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Laurent Falquet
- SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Frank Imkamp
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Peter M Keller
- Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland
| | - Andre Kahles
- SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Biomedical Informatics, Swiss Federal Institute of Technology (ETH Zürich), ETH Zürich, Zurich, Switzerland
| | - Simone Oberhaensli
- SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Interfaculty Bioinformatics Unit, University of Bern, Bern, Switzerland
| | - Valérie Barbié
- SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Christophe Dessimoz
- Department of Computational Biology, University of Lausanne, Lausanne, Switzerland.,Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland.,SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.,Department of Genetics, Evolution and Environment, University College London, London, United Kingdom.,Department of Computer Science, University College London, London, United Kingdom
| | - Gilbert Greub
- Institute of Microbiology, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland
| | - Aitana Lebrand
- SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland
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11
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Bourras S, Kunz L, Xue M, Praz CR, Müller MC, Kälin C, Schläfli M, Ackermann P, Flückiger S, Parlange F, Menardo F, Schaefer LK, Ben-David R, Roffler S, Oberhaensli S, Widrig V, Lindner S, Isaksson J, Wicker T, Yu D, Keller B. The AvrPm3-Pm3 effector-NLR interactions control both race-specific resistance and host-specificity of cereal mildews on wheat. Nat Commun 2019; 10:2292. [PMID: 31123263 PMCID: PMC6533294 DOI: 10.1038/s41467-019-10274-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 05/03/2019] [Indexed: 12/25/2022] Open
Abstract
The wheat Pm3 resistance gene against the powdery mildew pathogen occurs as an allelic series encoding functionally different immune receptors which induce resistance upon recognition of isolate-specific avirulence (AVR) effectors from the pathogen. Here, we describe the identification of five effector proteins from the mildew pathogens of wheat, rye, and the wild grass Dactylis glomerata, specifically recognized by the PM3B, PM3C and PM3D receptors. Together with the earlier identified AVRPM3A2/F2, the recognized AVRs of PM3B/C, (AVRPM3B2/C2), and PM3D (AVRPM3D3) belong to a large group of proteins with low sequence homology but predicted structural similarities. AvrPm3b2/c2 and AvrPm3d3 are conserved in all tested isolates of wheat and rye mildew, and non-host infection assays demonstrate that Pm3b, Pm3c, and Pm3d are also restricting the growth of rye mildew on wheat. Furthermore, divergent AVR homologues from non-adapted rye and Dactylis mildews are recognized by PM3B, PM3C, or PM3D, demonstrating their involvement in host specificity.
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Affiliation(s)
- Salim Bourras
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland.
- Department of Forest Mycology and Plant Pathology, Division of Plant Pathology, Swedish University of Agricultural Sciences, 750 07, Uppsala, Sweden.
| | - Lukas Kunz
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Minfeng Xue
- Institute of Plant Protection and Soil Science, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China
- Ministry of Agriculture Key Laboratory of Integrated Pest Management in Crops in Central China, Wuhan, 430064, China
- College of Life Science, Wuhan University, Wuhan, 430072, China
| | - Coraline Rosalie Praz
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Marion Claudia Müller
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Carol Kälin
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Michael Schläfli
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Patrick Ackermann
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Simon Flückiger
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Francis Parlange
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Fabrizio Menardo
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | | | - Roi Ben-David
- Institute of Plant Science, ARO-Volcani Center, 50250, Bet Dagan, Israel
| | - Stefan Roffler
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Simone Oberhaensli
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Victoria Widrig
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Stefan Lindner
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Jonatan Isaksson
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Thomas Wicker
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Dazhao Yu
- Institute of Plant Protection and Soil Science, Hubei Academy of Agricultural Sciences, Wuhan, 430064, China.
- Ministry of Agriculture Key Laboratory of Integrated Pest Management in Crops in Central China, Wuhan, 430064, China.
- College of Life Science, Wuhan University, Wuhan, 430072, China.
| | - Beat Keller
- Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland.
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12
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Praz CR, Bourras S, Zeng F, Sánchez‐Martín J, Menardo F, Xue M, Yang L, Roffler S, Böni R, Herren G, McNally KE, Ben‐David R, Parlange F, Oberhaensli S, Flückiger S, Schäfer LK, Wicker T, Yu D, Keller B. AvrPm2 encodes an RNase-like avirulence effector which is conserved in the two different specialized forms of wheat and rye powdery mildew fungus. New Phytol 2017; 213:1301-1314. [PMID: 27935041 PMCID: PMC5347869 DOI: 10.1111/nph.14372] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/02/2016] [Indexed: 05/20/2023]
Abstract
There is a large diversity of genetically defined resistance genes in bread wheat against the powdery mildew pathogen Blumeria graminis (B. g.) f. sp. tritici. Many confer race-specific resistance to this pathogen, but until now only the mildew avirulence gene AvrPm3a2/f2 that is recognized by Pm3a/f was known molecularly. We performed map-based cloning and genome-wide association studies to isolate a candidate for the mildew avirulence gene AvrPm2. We then used transient expression assays in Nicotiana benthamiana to demonstrate specific and strong recognition of AvrPm2 by Pm2. The virulent AvrPm2 allele arose from a conserved 12 kb deletion, while there is no protein sequence diversity in the gene pool of avirulent B. g. tritici isolates. We found one polymorphic AvrPm2 allele in B. g. triticale and one orthologue in B. g. secalis and both are recognized by Pm2. AvrPm2 belongs to a small gene family encoding structurally conserved RNase-like effectors, including Avra13 from B. g. hordei, the cognate Avr of the barley resistance gene Mla13. These results demonstrate the conservation of functional avirulence genes in two cereal powdery mildews specialized on different hosts, thus providing a possible explanation for successful introgression of resistance genes from rye or other grass relatives to wheat.
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Affiliation(s)
- Coraline R. Praz
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Salim Bourras
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Fansong Zeng
- Institute of Plant Protection and Soil ScienceHubei Academy of Agricultural SciencesWuhan430064China
- Ministry of Agriculture Key Laboratory of Integrated Pest Management in Crops in Central ChinaWuhan430064China
- College of Life ScienceWuhan UniversityWuhan430072China
| | | | - Fabrizio Menardo
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Minfeng Xue
- Institute of Plant Protection and Soil ScienceHubei Academy of Agricultural SciencesWuhan430064China
- Ministry of Agriculture Key Laboratory of Integrated Pest Management in Crops in Central ChinaWuhan430064China
- College of Life ScienceWuhan UniversityWuhan430072China
| | - Lijun Yang
- Institute of Plant Protection and Soil ScienceHubei Academy of Agricultural SciencesWuhan430064China
- Ministry of Agriculture Key Laboratory of Integrated Pest Management in Crops in Central ChinaWuhan430064China
- College of Life ScienceWuhan UniversityWuhan430072China
| | - Stefan Roffler
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Rainer Böni
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Gerard Herren
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Kaitlin E. McNally
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Roi Ben‐David
- Institute of Plant ScienceARO‐Volcani CenterBet Dagan50250Israel
| | - Francis Parlange
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Simone Oberhaensli
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Simon Flückiger
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Luisa K. Schäfer
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Thomas Wicker
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
| | - Dazhao Yu
- Institute of Plant Protection and Soil ScienceHubei Academy of Agricultural SciencesWuhan430064China
- Ministry of Agriculture Key Laboratory of Integrated Pest Management in Crops in Central ChinaWuhan430064China
- College of Life ScienceWuhan UniversityWuhan430072China
| | - Beat Keller
- Department of Plant and Microbial BiologyUniversity of ZürichZürich8008Switzerland
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13
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Amselem J, Vigouroux M, Oberhaensli S, Brown JKM, Bindschedler LV, Skamnioti P, Wicker T, Spanu PD, Quesneville H, Sacristán S. Evolution of the EKA family of powdery mildew avirulence-effector genes from the ORF 1 of a LINE retrotransposon. BMC Genomics 2015; 16:917. [PMID: 26556056 PMCID: PMC4641428 DOI: 10.1186/s12864-015-2185-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Accepted: 11/03/2015] [Indexed: 12/31/2022] Open
Abstract
Background The Avrk1 and Avra10 avirulence (AVR) genes encode effectors that increase the pathogenicity of the fungus Blumeria graminis f.sp. hordei (Bgh), the powdery mildew pathogen, in susceptible barley plants. In resistant barley, MLK1 and MLA10 resistance proteins recognize the presence of AVRK1 and AVRA10, eliciting the hypersensitive response typical of gene for gene interactions. Avrk1 and Avra10 have more than 1350 homologues in Bgh genome, forming the EKA (Effectors homologous to Avrk1 and Avra10) gene family. Results We tested the hypothesis that the EKA family originated from degenerate copies of Class I LINE retrotransposons by analysing the EKA family in the genome of Bgh isolate DH14 with bioinformatic tools specially developed for the analysis of Transposable Elements (TE) in genomes. The Class I LINE retrotransposon copies homologous to Avrk1 and Avra10 represent 6.5 % of the Bgh annotated genome and, among them, we identified 293 AVR/effector candidate genes. We also experimentally identified peptides that indicated the translation of several predicted proteins from EKA family members, which had higher relative abundance in haustoria than in hyphae. Conclusions Our analyses indicate that Avrk1 and Avra10 have evolved from part of the ORF1 gene of Class I LINE retrotransposons. The co-option of Avra10 and Avrk1 as effectors from truncated copies of retrotransposons explains the huge number of homologues in Bgh genome that could act as dynamic reservoirs from which new effector genes may evolve. These data provide further evidence for recruitment of retrotransposons in the evolution of new biological functions. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2185-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joelle Amselem
- INRA, UR1164 URGI Unité de Recherche Génomique-Info, Institut National de la Recherche Agronomique de Versailles-Grignon, Versailles, 78026, France. .,INRA, UR1290 BIOGER, Biologie et gestion des risques en agriculture, Campus AgroParisTech, 78850, Thiverval-Grignon, France.
| | | | - Simone Oberhaensli
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland.
| | - James K M Brown
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
| | | | - Pari Skamnioti
- Laboratory of Genetics, Department of Biotechnology, Agricultural University of Athens, Iera Odos 75, TK 11855, Athens, Greece.
| | - Thomas Wicker
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland.
| | - Pietro D Spanu
- Department of Life Sciences, Imperial College London, London, UK.
| | - Hadi Quesneville
- INRA, UR1164 URGI Unité de Recherche Génomique-Info, Institut National de la Recherche Agronomique de Versailles-Grignon, Versailles, 78026, France.
| | - Soledad Sacristán
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA) and E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, Campus de Montegancedo, Pozuelo de Alarcón, 28223, Madrid, Spain.
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14
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Bourras S, McNally KE, Ben-David R, Parlange F, Roffler S, Praz CR, Oberhaensli S, Menardo F, Stirnweis D, Frenkel Z, Schaefer LK, Flückiger S, Treier G, Herren G, Korol AB, Wicker T, Keller B. Multiple Avirulence Loci and Allele-Specific Effector Recognition Control the Pm3 Race-Specific Resistance of Wheat to Powdery Mildew. Plant Cell 2015; 27:2991-3012. [PMID: 26452600 PMCID: PMC4682313 DOI: 10.1105/tpc.15.00171] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 09/01/2015] [Accepted: 09/11/2015] [Indexed: 05/20/2023]
Abstract
In cereals, several mildew resistance genes occur as large allelic series; for example, in wheat (Triticum aestivum and Triticum turgidum), 17 functional Pm3 alleles confer agronomically important race-specific resistance to powdery mildew (Blumeria graminis). The molecular basis of race specificity has been characterized in wheat, but little is known about the corresponding avirulence genes in powdery mildew. Here, we dissected the genetics of avirulence for six Pm3 alleles and found that three major Avr loci affect avirulence, with a common locus_1 involved in all AvrPm3-Pm3 interactions. We cloned the effector gene AvrPm3(a2/f2) from locus_2, which is recognized by the Pm3a and Pm3f alleles. Induction of a Pm3 allele-dependent hypersensitive response in transient assays in Nicotiana benthamiana and in wheat demonstrated specificity. Gene expression analysis of Bcg1 (encoded by locus_1) and AvrPm3 (a2/f2) revealed significant differences between isolates, indicating that in addition to protein polymorphisms, expression levels play a role in avirulence. We propose a model for race specificity involving three components: an allele-specific avirulence effector, a resistance gene allele, and a pathogen-encoded suppressor of avirulence. Thus, whereas a genetically simple allelic series controls specificity in the plant host, recognition on the pathogen side is more complex, allowing flexible evolutionary responses and adaptation to resistance genes.
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Affiliation(s)
- Salim Bourras
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | | | - Roi Ben-David
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Francis Parlange
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Stefan Roffler
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | | | - Simone Oberhaensli
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Fabrizio Menardo
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Daniel Stirnweis
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Zeev Frenkel
- Institute of Evolution, University of Haifa, Mount Carmel, 31905 Haifa, Israel
| | | | - Simon Flückiger
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Georges Treier
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Gerhard Herren
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Abraham B Korol
- Institute of Evolution, University of Haifa, Mount Carmel, 31905 Haifa, Israel
| | - Thomas Wicker
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
| | - Beat Keller
- Institute of Plant Biology, University of Zurich, CH-8008 Zürich, Switzerland
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15
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Shatalina M, Wicker T, Buchmann JP, Oberhaensli S, Simková H, Doležel J, Keller B. Genotype-specific SNP map based on whole chromosome 3B sequence information from wheat cultivars Arina and Forno. Plant Biotechnol J 2013; 11:23-32. [PMID: 23046423 DOI: 10.1111/pbi.12003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 08/27/2012] [Accepted: 08/30/2012] [Indexed: 05/10/2023]
Abstract
Agronomically important traits are frequently controlled by rare, genotype-specific alleles. Such genes can only be mapped in a population derived from the donor genotype. This requires the development of a specific genetic map, which is difficult in wheat because of the low level of polymorphism among elite cultivars. The absence of sufficient polymorphism, the complexity of the hexaploid wheat genome as well as the lack of complete sequence information make the construction of genetic maps with a high density of reproducible and polymorphic markers challenging. We developed a genotype-specific genetic map of chromosome 3B from winter wheat cultivars Arina and Forno. Chromosome 3B was isolated from the two cultivars and then sequenced to 10-fold coverage. This resulted in a single-nucleotide polymorphisms (SNP) database of the complete chromosome. Based on proposed synteny with the Brachypodium model genome and gene annotation, sequences close to coding regions were used for the development of 70 SNP-based markers. They were mapped on a Arina × Forno Recombinant Inbred Lines population and found to be spread over the complete chromosome 3B. While overall synteny was well maintained, numerous exceptions and inversions of syntenic gene order were identified. Additionally, we found that the majority of recombination events occurred in distal parts of chromosome 3B, particularly in hot-spot regions. Compared with the earlier map based on SSR and RFLP markers, the number of markers increased fourfold. The approach presented here allows fast development of genotype-specific polymorphic markers that can be used for mapping and marker-assisted selection.
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16
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Parlange F, Oberhaensli S, Breen J, Platzer M, Taudien S, Simková H, Wicker T, Doležel J, Keller B. A major invasion of transposable elements accounts for the large size of the Blumeria graminis f.sp. tritici genome. Funct Integr Genomics 2011; 11:671-7. [PMID: 21809124 DOI: 10.1007/s10142-011-0240-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 07/03/2011] [Accepted: 07/17/2011] [Indexed: 10/17/2022]
Abstract
Powdery mildew of wheat (Triticum aestivum L.) is caused by the ascomycete fungus Blumeria graminis f.sp. tritici. Genomic approaches open new ways to study the biology of this obligate biotrophic pathogen. We started the analysis of the Bg tritici genome with the low-pass sequencing of its genome using the 454 technology and the construction of the first genomic bacterial artificial chromosome (BAC) library for this fungus. High-coverage contigs were assembled with the 454 reads. They allowed the characterization of 56 transposable elements and the establishment of the Blumeria repeat database. The BAC library contains 12,288 clones with an average insert size of 115 kb, which represents a maximum of 7.5-fold genome coverage. Sequencing of the BAC ends generated 12.6 Mb of random sequence representative of the genome. Analysis of BAC-end sequences revealed a massive invasion of transposable elements accounting for at least 85% of the genome. This explains the unusually large size of this genome which we estimate to be at least 174 Mb, based on a large-scale physical map constructed through the fingerprinting of the BAC library. Our study represents a crucial step in the perspective of the determination and study of the whole Bg tritici genome sequence.
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Affiliation(s)
- Francis Parlange
- Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, Zurich, Switzerland
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17
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Oberhaensli S, Parlange F, Buchmann JP, Jenny FH, Abbott JC, Burgis TA, Spanu PD, Keller B, Wicker T. Comparative sequence analysis of wheat and barley powdery mildew fungi reveals gene colinearity, dates divergence and indicates host-pathogen co-evolution. Fungal Genet Biol 2011; 48:327-34. [DOI: 10.1016/j.fgb.2010.10.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/29/2010] [Accepted: 10/06/2010] [Indexed: 12/24/2022]
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18
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Spanu PD, Abbott JC, Amselem J, Burgis TA, Soanes DM, Stüber K, Ver Loren van Themaat E, Brown JKM, Butcher SA, Gurr SJ, Lebrun MH, Ridout CJ, Schulze-Lefert P, Talbot NJ, Ahmadinejad N, Ametz C, Barton GR, Benjdia M, Bidzinski P, Bindschedler LV, Both M, Brewer MT, Cadle-Davidson L, Cadle-Davidson MM, Collemare J, Cramer R, Frenkel O, Godfrey D, Harriman J, Hoede C, King BC, Klages S, Kleemann J, Knoll D, Koti PS, Kreplak J, López-Ruiz FJ, Lu X, Maekawa T, Mahanil S, Micali C, Milgroom MG, Montana G, Noir S, O'Connell RJ, Oberhaensli S, Parlange F, Pedersen C, Quesneville H, Reinhardt R, Rott M, Sacristán S, Schmidt SM, Schön M, Skamnioti P, Sommer H, Stephens A, Takahara H, Thordal-Christensen H, Vigouroux M, Wessling R, Wicker T, Panstruga R. Genome expansion and gene loss in powdery mildew fungi reveal tradeoffs in extreme parasitism. Science 2010; 330:1543-6. [PMID: 21148392 DOI: 10.1126/science.1194573] [Citation(s) in RCA: 600] [Impact Index Per Article: 42.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Powdery mildews are phytopathogens whose growth and reproduction are entirely dependent on living plant cells. The molecular basis of this life-style, obligate biotrophy, remains unknown. We present the genome analysis of barley powdery mildew, Blumeria graminis f.sp. hordei (Blumeria), as well as a comparison with the analysis of two powdery mildews pathogenic on dicotyledonous plants. These genomes display massive retrotransposon proliferation, genome-size expansion, and gene losses. The missing genes encode enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, probably reflecting their redundancy in an exclusively biotrophic life-style. Among the 248 candidate effectors of pathogenesis identified in the Blumeria genome, very few (less than 10) define a core set conserved in all three mildews, suggesting that most effectors represent species-specific adaptations.
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Affiliation(s)
- Pietro D Spanu
- Department of Life Sciences, Imperial College London, London, UK.
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