Production of a Host-Specific, Wilt-Inducing Toxin in Apple Cell Suspension Cultures Inoculated with Erwinia amylovora

Hsu, Shih Tien

doi:10.1094/phyto-68-351

Cited by 20 publications

(8 citation statements)

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“…It has been postulated, on the basis of cut shoot and petiole wilt induction tests, that the ooze polysaccharide (amylovorin) is a host-specific toxin (Goodman et al, 1974Hsu & Goodman, 1978). These authors suggested that the polysaccharide might be used to evaluate varietal resistance of apple and pear to the fireblight bacterium, but Beer & Aldwinckle (1976) were unable to confirm this with shoots of apple cultivars and so far success has not been reported from other laboratories.…”

Section: Discussionmentioning

confidence: 99%

Origin of the Polysaccharide Component of Ooze from Plants Infected with Erwinia amylovora

Bennett¹,

Billing

1980

Microbiology

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The composition of extracellular polysaccharides produced by Erwinia amylovora in defined culture media was compared with that of the polysaccharide present in the ooze produced during fireblight infection. The results strongly suggested that the ooze polysaccharide was of bacterial origin.Two distinct polysaccharides were produced in vitro. One contained galactose (61 to 69(%), glucose (8 to 11 yo), mannose (2 to 6 yo) and uronic acid (16 to 23 yo) and the other contained only fructose. Both the quantity and composition of the polysaccharide produced was determined by the nature and concentration of the sugar or sugar alcohol supplied and by the nature of the nitrogen source. Evidence is also presented which suggests that production of the ooze-like polysaccharide is a virulence determinant and that this polysaccharide is similar in composition to the capsule. Preliminary studies indicate the presence of capsule and polysaccharide-hydrolysing enzymes in lysates of phage-infected bacteria.

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Section: Discussionmentioning

confidence: 99%

Origin of the Polysaccharide Component of Ooze from Plants Infected with Erwinia amylovora

Bennett¹,

Billing

1980

Microbiology

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“…The dense layer of EPS is supposed to shield invading microorganisms against host defense systems like the hypersensitive response reaction. It might further prevent cell aggregation by agglutinins, and it has been reported to accelerate the wilting of infected plants by plugging xylem vessels (4).…”

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confidence: 99%

Identification of an RcsA/RcsB Recognition Motif in the Promoters of Exopolysaccharide Biosynthetic Operons from Erwinia amylovora and Pantoea stewartii Subspeciesstewartii

Wehland¹,

Kiecker²,

Coplin³

et al. 1999

Journal of Biological Chemistry

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The regulation of capsule synthesis (Rcs) regulatory network is responsible for the induction of exopolysaccharide biosynthesis in many enterobacterial species. We have previously shown that two transcriptional regulators, RcsA and RcsB, do bind as a heterodimer to the promoter of amsG, the first reading frame in the operon for amylovoran biosynthesis in the plant pathogenic bacterium Erwinia amylovora. We now identified a 23-base pair fragment from position ؊555 to ؊533 upstream of the translational start site of amsG as sufficient for the specific binding of the Rcs proteins. In addition, we could detect an RcsA/RcsB-binding site in a corresponding region of the promoter of cpsA, the homologous counterpart to the E. amylovora amsG gene in the operon for stewartan biosynthesis of Pantoea stewartii. The specificity and characteristic parameters of the protein-DNA interaction were analyzed by DNA retardation, protein-DNA cross-linking, and directed mutagenesis. The central core motif TRVGAAWAWTSYG of the amsG promoter was found to be most important for the specific interaction with RcsA/RcsB, as evaluated by mutational analysis and an in vitro selection approach. The wild type P. stewartii Rcs binding motif is degenerated in two positions and an up-mutation according to our consensus motif resulted in about a 5-fold increased affinity of the RcsA/RcsB proteins.The ability to produce capsules or exopolysaccharides (EPS) 1 is characteristic for most bacterial species. General benefits of encapsulation are the prevention of desiccation, advantages in the degradation of substrates by adherence, and the binding of toxins and nutrients (1). EPS is furthermore an essential determinant for the bacterial virulence in several host-pathogen interactions (2), e.g. during infections by the plant pathogenic bacteria Erwinia amylovora and Pantoea stewartii subsp. stewartii (Ref. 3; formerly Erwinia stewartii). The dense layer of EPS is supposed to shield invading microorganisms against host defense systems like the hypersensitive response reaction. It might further prevent cell aggregation by agglutinins, and it has been reported to accelerate the wilting of infected plants by plugging xylem vessels (4).The EPS structure is highly variable, and different types have been classified by molecular weight and structural properties (5). The biosynthesis of the high molecular weight EPS type IA in several enterobacterial species is modulated by the Rcs (regulation of capsule synthesis) regulatory network (6). Prominent examples are the regulation of colanic acid and many K antigens in Escherichia coli (7,8), Klebsiella aerogenes (9 -11), and Salmonella typhi (12). In plant pathogenic bacteria, the regulation of amylovoran synthesis in E. amylovora (13-16) and stewartan synthesis in P. stewartii (17) by Rcs proteins has been reported. EPS biosynthesis is supposed to be induced after perception of external signals by membranelocated sensors like the RcsC protein. The signal might be subsequently transduced by phosphorylation of the resp...

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“…In vitro, E. amylovora produces these same EPS, which are either tightly bound to the cell to form a capsule or run freely on the medium to constitute the slime (2,7,53). To date, EPS are the only components known to be involved in the pathogenicity of this bacterium (5,6); however their role is still controversial (4,25,27,31,46,52). Recently, Steinberger and Beer isolated TnS-induced mutants of E. amylovora affected in pathogenicity by using the suicide vector pJB4JI (55).…”

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Bacteriophage Mu as a genetic tool to study Erwinia amylovora pathogenicity and hypersensitive reaction on tobacco

1990

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Erwinia amylovora 1430 was shown to be sensitive to Mu G(-) particles. Infection resulted either in lytic development or in lysogenic derivatives with insertion of the Mu genome at many sites in the bacterial chromosome. We used the Mu d1Bx::Tn9 (lac Apr Cmr) derivative, called Mu dX, to identify mutants affected in pathogenicity and in their ability to induce a hypersensitive reaction (HR) on tobacco plants. Inoculation of 1,400 lysogenic derivatives on apple root calli led to the identification of 12 mutants in three classes: (i) class 1 mutants were nonpathogenic and unable to induce an HR on tobacco plants; (ii) class 2 mutants were nonpathogenic but retained the ability to induce an HR; and (iii) class 3 mutants showed attenuated virulence. Of the 12 mutants, 8 had a single insertion of the Mu dX prophage. For class 1 and 2 mutants, reversion to pathogenicity was concomitant with the loss of the Mu dX prophage. Furthermore, revertants from the class 1 mutants also recovered the ability to induce an HR on tobacco plants. Five of the six class 3 mutants were impaired in exopolysaccharide production. No changes of the envelope structure (lipopolysaccharide and outer membrane proteins) were correlated with differences in pathogenicity. One class 3 mutant did not produce any functional siderophore, suggesting that iron uptake could be involved in pathogenicity.

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Production of a Host-Specific, Wilt-Inducing Toxin in Apple Cell Suspension Cultures Inoculated with Erwinia amylovora

Cited by 20 publications

References 0 publications

Origin of the Polysaccharide Component of Ooze from Plants Infected with Erwinia amylovora

Origin of the Polysaccharide Component of Ooze from Plants Infected with Erwinia amylovora

Identification of an RcsA/RcsB Recognition Motif in the Promoters of Exopolysaccharide Biosynthetic Operons from Erwinia amylovora and Pantoea stewartii Subspeciesstewartii

Bacteriophage Mu as a genetic tool to study Erwinia amylovora pathogenicity and hypersensitive reaction on tobacco

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