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Youfu Zhao - One of the best experts on this subject based on the ideXlab platform.
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complete genome sequence of the fire blight pathogen strain Erwinia amylovora ea1189
Molecular Plant-microbe Interactions, 2020Co-Authors: Jugpreet Singh, George W. Sundin, Awais Khan, Youfu ZhaoAbstract:Erwinia amylovora causes fire blight, the most devastating bacterial disease of apples and pears in the United States and worldwide. The model strain E. amylovora Ea1189 has been extensively used to understand bacterial pathogenesis and molecular mechanisms of bacterial-plant interactions. In this work, we sequenced and assembled the de novo genome of Ea1189, using a combination of long Oxford Nanopore Technologies and short Illumina sequence reads. A complete gapless genome assembly of Ea1189 consists of a 3,797,741-bp circular chromosome and a 28,259-bp plasmid with 3,472 predicted genes, including 78 transfer RNAs, 22 ribosomal RNAs, and 20 noncoding RNAs. A comparison of the Ea1189 genome to previously sequenced E. amylovora complete genomes showed 99.94 to 99.97% sequence similarity with 314 to 946 single nucleotide polymorphisms. We believe that the availability of the complete genome sequence of strain Ea1189 will further support studies to understand evolution, diversity and structural variations of Erwinia strains, as well as the molecular basis of E. amylovora pathogenesis and its interactions with host plants, thus facilitating the development of effective management strategies for this important disease.
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Characterization of genes involved in (p)ppGpp precursor biosynthesis in Erwinia amylovora
Journal of Plant Pathology, 2020Co-Authors: Ho-wen Yang, Menghao Yu, Awais Khan, Youfu ZhaoAbstract:Previous studies have shown that the hypersensitive response and pathogenicity ( hrp )-type III secretion system (T3SS) is activated by the bacterial alarmone (p)ppGpp, which mediates the stringent response in nutrient starvation conditions in Erwinia amylovora . ATP and GTP, the precursors of (p)ppGpp biosynthesis, are synthesized from AMP/adenine and GMP/guanine, respectively, by the de novo pathway of purine biosynthesis. In this study, we examined the role of the purA/purB and guaA/guaB genes, which are involved in the AMP/adenine and GMP/guanine biosynthesis, respectively. Our results showed that growth of the purA , purB , and guaAB mutants was much slower in minimal media, but could be restored by addition of exogenous AMP/adenine and GMP/guanine, respectively. However, mixed results were obtained for their contribution to virulence on immature pear fruits. These results suggested that the de novo purine biosynthesis pathway might be required for proliferation, colonization and infection of E. amylovora .
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Erwinia amylovora in the genomics era from genomes to pathogen virulence regulation and disease control strategies
Journal of Plant Pathology, 2017Co-Authors: Theo H M Smits, George W. Sundin, Brion Duffy, Youfu Zhao, Fabio RezzonicoAbstract:The publication of the first Erwinia amylovora genome has greatly accelerated and advanced our understanding of the fire blight organism. With the availability of multiple genomes, it quickly became clear that chromosomal diversity is relatively small, and that most of the pan-genome variance is attributable to plasmids. In addition to gaining a more detailed view of the known virulence factors, genomics has enabled new breakthrough studies of virulence regulation mechanisms. Furthermore, several niche adaptation and ecological fitness factors, though not directly influencing virulence, have been studied in greater detail, providing novel insights into the physiology and ecology of the bacterium. Additionally, application of genome data has yielded improved diagnostics and enabled population studies at different geographic scales.
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Genomics of Erwinia amylovora and Related Erwinia Species Associated with Pome Fruit Trees
Genomics of Plant-Associated Bacteria, 2014Co-Authors: Youfu ZhaoAbstract:Erwinia amylovora, the causal agent of fire blight disease of apples and pears, is one of the most important plant bacterial pathogens with worldwide economic significance. In this chapter, the author describes up-to-date information about the genomes of E. amylovora and related Erwinia species primarily associated with pome fruit trees, provides recent developments in genome-enabled understanding of E. amylovora virulence, and highlights latest comparative and functional genomic studies of E. amylovora, including proteomics and transcriptomics, in understanding the biology, population diversity, and evolution of this important group of pathogens. The chapter also summarizes the current progress in understanding of the pathogen and its virulence mechanism from genome sequencing data, as well as the potential evolutionary origin of these Erwinia species. In the introduction part, the chapter contains comprehensive information about the distribution, economic losses, and spread of the fire blight disease, the characteristics of the pathogen as well as its key features associated with virulence factors and regulatory systems, including type III secretion systems and the exopolysaccharide amylovoran. Future perspectives and research directions from systems biology to host–pathogen interactions are also suggested.
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small molecule inhibitors suppress the expression of both type iii secretion and amylovoran biosynthesis genes in Erwinia amylovora
Molecular Plant Pathology, 2014Co-Authors: Fan Yang, George W. Sundin, Schuyler S Korban, Lawrence P Pusey, Michael Elofsson, Youfu ZhaoAbstract:The type III secretion system (T3SS) and exopolysaccharide (EPS) amylovoran are two essential pathogenicity factors in Erwinia amylovora, the causal agent of the serious bacterial disease fire blig ...
Klaus Geider - One of the best experts on this subject based on the ideXlab platform.
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Complete genome sequences of three Erwinia amylovora phages isolated in north america and a bacteriophage induced from an Erwinia tasmaniensis strain.
Journal of bacteriology, 2010Co-Authors: Ina Müller, Michael Kube, Richard Reinhardt, Wilhelm Jelkmann, Klaus GeiderAbstract:Fire blight, a plant disease of economic importance caused by Erwinia amylovora, may be controlled by the application of bacteriophages. Here, we provide the complete genome sequences and the annotation of three E. amylovora-specific phages isolated in North America and genomic information about a bacteriophage induced by mitomycin C treatment of an Erwinia tasmaniensis strain that is antagonistic for E. amylovora. The American phages resemble two already-described viral genomes, whereas the E. tasmaniensis phage displays a singular genomic sequence in BLAST searches.
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Autoinducer-2 of the fire blight pathogen Erwinia amylovora and other plant-associated bacteria
Fems Microbiology Letters, 2006Co-Authors: Mojtaba Mohammadi, Klaus GeiderAbstract:Autoinducers are important for cellular communication of bacteria. The luxS gene has a central role in the synthesis of autoinducer-2 (AI-2). The gene was identified in a shotgun library of Erwinia amylovora and primers designed for PCR amplification from bacterial DNA. Supernatants of several Erwinia amylovora strains were assayed for AI-2 activity with a Vibrio harveyi mutant and were positive. Many other plant-associated bacteria also showed AI-2 activity such as Erwinia pyrifoliae and Erwinia tasmaniensis. The luxS genes of several bacteria were cloned, sequenced, and complemented Escherichia coli strain DH5α and a Salmonella typhimurium mutant, both defective in luxS, for synthesis of AI-2. Assays to detect AI-2 activity in culture supernatants of several Pseudomonas syringae pathovars failed, which may indicate the absence of AI-2 or synthesis of another type. Several reporter strains did not detect synthesis of an acyl homoserine lactone (AHL, AI-1) by Erwinia amylovora, but confirmed AHL-synthesis for Erwinia carotovora ssp. atroseptica and Pantoea stewartii.
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real time pcr for detection and quantification of Erwinia amylovora the causal agent of fireblight
Plant Pathology, 2004Co-Authors: H Salm, Klaus GeiderAbstract:Real-time PCR was used for quantitative detection of Erwinia amylovora, the causative agent of fireblight. Specific primers were created from a DNA fragment of the common plasmid pEA29, successfully used for standard PCR identification of the pathogen. The primers amplified DNA from various E. amylovora strains, but not from other plant-associated bacteria. DNA of E. amylovora was also amplified from field samples and from inoculated apple leaves or flowers. Neither the presence of other bacteria nor low amounts of tissue extracts from bark or leaves changed the signal threshold. Assays with SYBR Green I instead of the Taqman probe showed a similar sensitivity, detecting 50 cells per assay. Real-time PCR could be especially useful for mass screening of commercial products and for resistance studies of transgenic host plants, in breeding experiments and after treatments to control fireblight.
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Molecular comparison of pathogenic bacteria from pear trees in Japan and the fire blight pathogen Erwinia amylovora.
Microbiology (Reading England), 2001Co-Authors: W S Kim, M Hildebrand, S Jock, Klaus GeiderAbstract:Several strains of the genus Erwinia, which were isolated in Japan from pear trees with necrotic symptoms that resembled fire blight, and tentatively identified as Erwinia amylovora, were reinvestigated for their relationship to the fire blight pathogen. These isolates produced ooze on slices of immature pears and were mucoid on MM2Cu agar plates, but did not synthesize levan and did not give the expected PCR signals with several primer pairs specific for Erwinia amylovora. The isolates tested positive with PCR primers designed to detect the novel pear pathogen Erwinia pyrifoliae, which was isolated from Nashi pear trees in South Korea. The nucleotide sequence analysis of a DNA fragment preceding the gene cluster for exopolysaccharide synthesis revealed a closer relationship to Erwinia pyrifoliae than to Erwinia amylovora. Plasmid profiles, protein patterns and genomic DNA analysed by PFGE after XbaI and SpeI digestion were different than Erwinia amylovora. Experiments with strains of Erwinia amylovora isolated from raspberry (Rubus sp.), Erwinia mallotivora and Enterobacter pyrinus also did not reveal a relationship between these bacteria and the Japanese Erwinia strains. The latter are not identical to Erwinia pyrifoliae, but possess many similar features to this pathogen that causes Asian pear blight. It is concluded that pathogenic bacteria isolated in Japan from pear trees with symptoms resembling fire blight are possibly different from Erwinia amylovora.
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Characterization of a gene locus from Erwinia amylovora with regulatory functions in exopolysaccharide synthesis of Erwinia spp.
Canadian journal of microbiology, 1998Co-Authors: Phillip D. Aldridge, David L. Coplin, Frank Bernhard, Peter Bugert, Klaus GeiderAbstract:In a genomic library of Erwinia amylovora, a locus has been identified that can suppress an Erwinia stewartii rcsA mutant. In addition, the locus induced a mucoid sticky phenotype of colonies in a wild-type strain of Erwinia stewartii and increased exopolysaccharide synthesis in several species of bacteria belonging to the genus Erwinia. An open reading frame was identified at this locus encoding a 225 amino acid protein that contained a helix-turn-helix motif typical of transcriptional regulators. The corresponding gene was subsequently named rcsV (regulator of capsular synthesis affecting viscosity). A mutant of rcsV in wild-type Erwinia amylovora had no detectable phenotype and produced typical levels of amylovoran under laboratory conditions. The rcsV gene on a high copy number plasmid under the control of its own promoter did not alter amylovoran production, in contrast to in-frame fusions of the structural gene in expression vectors. Since even the lac promoter was inert in the expression of rcsV, a DNA-binding protein could inhibit transcription of the gene in Erwinia amylovora. On the other hand, an Erwinia amylovora rcsA mutant was suppressed by rcsV when its promoter was replaced and the structural gene fused in-frame with lacZ' or malE. Northern blots, with total RNA from Erwinia amylovora, or promoter analysis using the GUS reporter gene did not show expression of rcsV in Erwinia amylovora, although primer extension analysis did. RcsV could be a component involved in the regulation of amylovoran synthesis, and gene expression may require an unknown external signal during the life cycle or pathogenesis of Erwinia amylovora.
George W. Sundin - One of the best experts on this subject based on the ideXlab platform.
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complete genome sequence of the fire blight pathogen strain Erwinia amylovora ea1189
Molecular Plant-microbe Interactions, 2020Co-Authors: Jugpreet Singh, George W. Sundin, Awais Khan, Youfu ZhaoAbstract:Erwinia amylovora causes fire blight, the most devastating bacterial disease of apples and pears in the United States and worldwide. The model strain E. amylovora Ea1189 has been extensively used to understand bacterial pathogenesis and molecular mechanisms of bacterial-plant interactions. In this work, we sequenced and assembled the de novo genome of Ea1189, using a combination of long Oxford Nanopore Technologies and short Illumina sequence reads. A complete gapless genome assembly of Ea1189 consists of a 3,797,741-bp circular chromosome and a 28,259-bp plasmid with 3,472 predicted genes, including 78 transfer RNAs, 22 ribosomal RNAs, and 20 noncoding RNAs. A comparison of the Ea1189 genome to previously sequenced E. amylovora complete genomes showed 99.94 to 99.97% sequence similarity with 314 to 946 single nucleotide polymorphisms. We believe that the availability of the complete genome sequence of strain Ea1189 will further support studies to understand evolution, diversity and structural variations of Erwinia strains, as well as the molecular basis of E. amylovora pathogenesis and its interactions with host plants, thus facilitating the development of effective management strategies for this important disease.
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phosphodiesterase genes regulate amylovoran production biofilm formation and virulence in Erwinia amylovora
Applied and Environmental Microbiology, 2018Co-Authors: Roshni R Kharadi, Luisa F Castiblanco, Christopher M Waters, George W. SundinAbstract:ABSTRACT Cyclic di-GMP (c-di-GMP) is a ubiquitous bacterial second messenger molecule that is an important virulence regulator in the plant pathogen Erwinia amylovora. Intracellular levels of c-di-GMP are modulated by diguanylate cyclase (DGC) enzymes that synthesize c-di-GMP and by phosphodiesterase (PDE) enzymes that degrade c-di-GMP. The regulatory role of the PDE enzymes in E. amylovora has not been determined. Using a combination of single, double, and triple deletion mutants, we determined the effects of each of the four putative PDE-encoding genes (pdeA, pdeB, pdeC, and edcA) in E. amylovora on cellular processes related to virulence. Our results indicate that pdeA and pdeC are the two phosphodiesterases most active in virulence regulation in E. amylovora Ea1189. The deletion of pdeC resulted in a measurably significant increase in the intracellular pool of c-di-GMP, and the highest intracellular concentrations of c-di-GMP were observed in the Ea1189 ΔpdeAC and Ea1189 ΔpdeABC mutants. The regulation of virulence traits due to the deletion of the pde genes showed two patterns. A stronger regulatory effect was observed on amylovoran production and biofilm formation, where both Ea1189 ΔpdeA and Ea1189 ΔpdeC mutants exhibited significant increases in these two phenotypes in vitro. In contrast, the deletion of two or more pde genes was required to affect motility and virulence phenotypes. Our results indicate a functional redundancy among the pde genes in E. amylovora for certain traits and indicate that the intracellular degradation of c-di-GMP is mainly regulated by pdeA and pdeC, but they also suggest a role for pdeB in regulating motility and virulence. IMPORTANCE Precise control of the expression of virulence genes is essential for successful infection of apple hosts by the fire blight pathogen, Erwinia amylovora. The presence and buildup of a signaling molecule called cyclic di-GMP enables the expression and function of some virulence determinants in E. amylovora, such as amylovoran production and biofilm formation. However, other determinants, such as those for motility and the type III secretion system, are expressed and functional when cyclic di-GMP is absent. Here, we report studies of enzymes called phosphodiesterases, which function in the degradation of cyclic di-GMP. We show the importance of these enzymes in virulence gene regulation and the ability of E. amylovora to cause plant disease.
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Erwinia amylovora in the genomics era from genomes to pathogen virulence regulation and disease control strategies
Journal of Plant Pathology, 2017Co-Authors: Theo H M Smits, George W. Sundin, Brion Duffy, Youfu Zhao, Fabio RezzonicoAbstract:The publication of the first Erwinia amylovora genome has greatly accelerated and advanced our understanding of the fire blight organism. With the availability of multiple genomes, it quickly became clear that chromosomal diversity is relatively small, and that most of the pan-genome variance is attributable to plasmids. In addition to gaining a more detailed view of the known virulence factors, genomics has enabled new breakthrough studies of virulence regulation mechanisms. Furthermore, several niche adaptation and ecological fitness factors, though not directly influencing virulence, have been studied in greater detail, providing novel insights into the physiology and ecology of the bacterium. Additionally, application of genome data has yielded improved diagnostics and enabled population studies at different geographic scales.
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microbiological examination of Erwinia amylovora exopolysaccharide ooze
Phytopathology, 2017Co-Authors: Suzanne M Slack, Quan Zeng, Cory Outwater, George W. SundinAbstract:Fire blight, caused by the pathogen Erwinia amylovora, is the most devastating bacterial disease of pome fruit in North America and worldwide. The primary method of dispersal for E. amylovora is through ooze, a mass of exopolysaccharides and bacterial cells that is exuded as droplets from infected host tissue. During the 2013 and 2014 field seasons, 317 ooze droplets were collected from field-inoculated apple trees. Populations of E. amylovora in ooze droplets were 108 CFU/μl on average. Ooze droplets harboring larger (>108 CFU/μl) cell populations were typically smaller in total volume and had darker coloring, such as orange, red, or dark red hues. Examination of apple host tissue at the site of emergence of ooze droplets using scanning electron microscopy revealed that ooze was not exuding through natural openings; instead, it was found on erumpent mounds and small (10-μm) tears in tissue. These observations suggested that E. amylovora-induced wounds in tissue provided the exit holes for ooze extrusion ...
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small molecule inhibitors suppress the expression of both type iii secretion and amylovoran biosynthesis genes in Erwinia amylovora
Molecular Plant Pathology, 2014Co-Authors: Fan Yang, George W. Sundin, Schuyler S Korban, Lawrence P Pusey, Michael Elofsson, Youfu ZhaoAbstract:The type III secretion system (T3SS) and exopolysaccharide (EPS) amylovoran are two essential pathogenicity factors in Erwinia amylovora, the causal agent of the serious bacterial disease fire blig ...
Herb S Aldwinckle - One of the best experts on this subject based on the ideXlab platform.
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identification of genes differentially expressed during interaction of resistant and susceptible apple cultivars malus domestica with Erwinia amylovora
BMC Plant Biology, 2010Co-Authors: Angela M Baldo, Herb S Aldwinckle, Jay Norelli, Robert E Farrell, Carole L Bassett, Mickael MalnoyAbstract:Background The necrogenic enterobacterium, Erwinia amylovora is the causal agent of the fire blight (FB) disease in many Rosaceaespecies, including apple and pear. During the infection process, the bacteria induce an oxidative stress response with kinetics similar to those induced in an incompatible bacteria-plant interaction. No resistance mechanism to E. amylovora in host plants has yet been characterized, recent work has identified some molecular events which occur in resistant and/or susceptible host interaction with E. amylovora: In order to understand the mechanisms that characterize responses to FB, differentially expressed genes were identified by cDNA-AFLP analysis in resistant and susceptible apple genotypes after inoculation with E. amylovora.
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isolation of streptomycin resistant isolates of Erwinia amylovora in new york
Plant Disease, 2008Co-Authors: Nicole L Russo, Thomas J Burr, Deborah I Breth, Herb S AldwinckleAbstract:ABSTRACT Streptomycin is currently the only antibiotic registered for the control of fire blight, a devastating disease of apple (Malus), pear (Pyrus), and other rosaceous plants caused by the bacterium Erwinia amylovora. Resistance of E. amylovora to streptomycin was first identified in California pear orchards in 1971 and is currently endemic in many parts of the United States. The Northeast remains the only major U.S. apple-growing region without streptomycin-resistant isolates of E. amylovora. In 2002, during a routine survey for streptomycin resistance, isolates from two neighboring orchards in Wayne County, NY were found to be highly resistant to streptomycin at a concentration of 100 μg/ml. This constitutes the first authenticated report of streptomycin resistance in New York State. Infected trees were shipped at the same time from a single nursery in Michigan. Resistance was caused by the acquisition of the strA-strB gene pair, inserted into the ubiquitous nontransmissible E. amylovora plasmid pEA...
Steven V Beer - One of the best experts on this subject based on the ideXlab platform.
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genome sequence of an Erwinia amylovora strain with pathogenicity restricted to rubus plants
Journal of Bacteriology, 2011Co-Authors: Rachel Powney, Theo H M Smits, Jochen Blom, Juerg E Frey, Tim Sawbridge, Beatrice Frey, Kim M Plummer, Steven V Beer, Joanne E LuckAbstract:Here, we present the genome of a strain of Erwinia amylovora, the fire blight pathogen, with pathogenicity restricted to Rubus spp. Comparative genomics of ATCC BAA-2158 with E. amylovora strains from non-Rubus hosts identified significant genetic differences but support the inclusion of this strain within the species E. amylovora.
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the specificity of pcr based protocols for detection of Erwinia amylovora
Australasian Plant Pathology, 2011Co-Authors: Rachel Powney, Kim M Plummer, Steven V Beer, Jo Luck, Brendan RodoniAbstract:An evaluation of seven published conventional PCR protocols used for the detection of Erwinia amylovora has shown that six out of the seven protocols tested were not specific for all strains of E. amylovora. A collection of 40 genetically diverse strains of E. amylovora and 55 geographically diverse bacteria that are closely related or share the same ecological niche as E. amylovora were used to test the seven PCR protocols. All bacteria were tested for virulence by inoculation of immature pear fruit and for cultural characteristics on selective media. Only one PCR protocol, Taylor et al. (2001), was specific for all strains of E. amylovora and was able to differentiate E. amylovora from all other bacteria tested. Diagnostic laboratories may need to review their testing procedures in light of these findings.
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molecular genetics of Erwinia amylovora involved in the development of fire blight
Fems Microbiology Letters, 2005Co-Authors: Steven V BeerAbstract:The bacterial plant pathogen, Erwinia amylovora, causes the devastating disease known as fire blight in some Rosaceous plants like apple, pear, quince, raspberry and several ornamentals. Knowledge of the factors affecting the development of fire blight has mushroomed in the last quarter century. On the molecular level, genes encoding a Hrp type III secretion system, genes encoding enzymes involved in synthesis of extracellular polysaccharides and genes facilitating the growth of E. amylovora in its host plants have been characterized. The Hrp pathogenicity island, delimited by genes suggesting horizontal gene transfer, is composed of four distinct regions, the hrp/hrc region, the HEE (Hrp effectors and elicitors) region, the HAE (Hrp-associated enzymes) region, and the IT (Island transfer) region. The Hrp pathogenicity island encodes a Hrp type III secretion system (TTSS), which delivers several proteins from bacteria to plant apoplasts or cytoplasm. E. amylovora produces two exopolysaccharides, amylovoran and levan, which cause the characteristic fire blight wilting symptom in host plants. In addition, other genes, and their encoded proteins, have been characterized as virulence factors of E. amylovora that encode enzymes facilitating sorbitol metabolism, proteolytic activity and iron harvesting. This review summarizes our understanding of the genes and gene products of E. amylovora that are involved in the development of the fire blight disease.
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Erwinia amylovora secretes dspe a pathogenicity factor and functional avre homolog through the hrp type iii secretion pathway
Journal of Bacteriology, 1998Co-Authors: Adam J Bogdanove, David W Bauer, Steven V BeerAbstract:Erwinia amylovora was shown to secrete DspE, a pathogenicity factor of 198 kDa and a functional homolog of AvrE of Pseudomonas syringae pv. tomato. DspE was identified among the supernatant proteins isolated from cultures grown in an hrp gene-inducing minimal medium by immunodetection with a DspE-specific antiserum. Secretion required an intact Hrp pathway.
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harpin elicitor of the hypersensitive response produced by the plant pathogen Erwinia amylovora
Science, 1992Co-Authors: Zhongmin Wei, David W Bauer, Ron Laby, Cathy H Zumoff, Alan Collmer, Steven V BeerAbstract:A proteinaceous elicitor of the plant defense reaction known as the hypersensitive response was isolated from Erwinia amylovora, the bacterium that causes fire blight of pear, apple, and other rosaceous plants. The elicitor, named harpin, is an acidic, heat-stable, cell-envelope-associated protein with an apparent molecular weight of 44 kilodaltons. Harpin caused tobacco leaf lamina to collapse and caused an increase in the pH of bathing solutions of suspension-cultured tobacco cells. The gene encoding harpin (hrpN) was located in the 40-kilobase hrp gene cluster of E. amylovora, sequenced, and mutated with Tn5tac1. The hrpN mutants were not pathogenic to pear, did not elicit the hypersensitive response, and did not produce harpin.