Dynamics of RP4 plasmid transfer between Xanthomonas campestris pv. corylina and Erwinia herbicola in hazelnut tissues, in planta

1986 ◽  
Vol 32 (11) ◽  
pp. 835-841 ◽  
Author(s):  
Charles Manceau ◽  
Louis Gardan ◽  
Martine Devaux
Keyword(s):  
Pseudomonas Fluorescens ◽  
Xanthomonas Campestris ◽  
Plasmid Transfer ◽  
In Planta ◽  
Erwinia Herbicola ◽  
Bacterial Populations ◽  
Physiological Conditions ◽  
Factor Governing ◽  
Host Tissues ◽  
Main Factor

We have shown that the transfer of plasmid RP4 took place between two strains of Xanthomonas campestris pv. corylina and from Xanthomonas campestris pv. corylina to Erwinia herbicola and vice versa when the strains were inoculated in hazelnut tissues in an experimental orchard. Transfer occurred throughout all seasons and was independent of the physiological conditions of the host tissues. The main factor governing transfer in planta appeared to be the frequency of contacts among donors and recipients. The frequency of transfer was correlated with the level of bacterial populations. RP4 was stable in the inoculated strains of Xanthomonas campestris pv. corylina as well as in Erwinia herbicola in hazelnut tissue. RP4 was detected in two isolates of resident epiphytic microflora, Pseudomonas fluorescens and Erwinia herbicola.

scholarly journals Detection and Visualization of an Exopolysaccharide Produced by Xylella fastidiosa In Vitro and In Planta

2007 ◽  
Vol 73 (22) ◽  
pp. 7252-7258 ◽  
Author(s):  
M. Caroline Roper ◽  
L. Carl Greve ◽  
John M. Labavitch ◽  
Bruce C. Kirkpatrick
Keyword(s):  
Xanthan Gum ◽  
Xanthomonas Campestris ◽  
Polyclonal Antibodies ◽  
Xylella Fastidiosa ◽  
Enzyme Linked Immunosorbent Assay ◽  
In Planta ◽  
Mannose Residue ◽  
Pantoea Stewartii ◽  
Vascular Occlusions

ABSTRACT Many phytopathogenic bacteria, such as Ralstonia solanacearum, Pantoea stewartii, and Xanthomonas campestris, produce exopolysaccharides (EPSs) that aid in virulence, colonization, and survival. EPS can also contribute to host xylem vessel blockage. The genome of Xylella fastidiosa, the causal agent of Pierce's disease (PD) of grapevine, contains an operon that is strikingly similar to the X. campestris gum operon, which is responsible for the production of xanthan gum. Based on this information, it has been hypothesized that X. fastidiosa is capable of producing an EPS similar in structure and composition to xanthan gum but lacking the terminal mannose residue. In this study, we raised polyclonal antibodies against a modified xanthan gum polymer similar to the predicted X. fastidiosa EPS polymer. We used enzyme-linked immunosorbent assay to quantify production of EPS from X. fastidiosa cells grown in vitro and immunolocalization microscopy to examine the distribution of X. fastidiosa EPS in biofilms formed in vitro and in planta and assessed the contribution of X. fastidiosa EPS to the vascular occlusions seen in PD-infected grapevines.

Comparative analysis of five methods for recovering rhizobacteria from cotton roots

1991 ◽  
Vol 37 (12) ◽  
pp. 953-957 ◽  
Author(s):  
Joseph W. Kloepper ◽  
Walter F. Mahaffee ◽  
John A. McInroy ◽  
Paul A. Backman
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Fluorescens ◽  
Standard Error ◽  
Root Colonization ◽  
Glass Beads ◽  
Standard Errors ◽  
Subtilis Strain ◽  
Bacterial Populations ◽  
Recovery Method ◽  
Cotton Seeds

A variety of methods have been used for recovering introduced bacteria from plant roots. The objective of this study was to compare systematically five methods: agitation in buffer, agitation with glass beads in buffer, mixing in a StomacherR lab-blender, sonication, and trituration with mortar and pestle. Cotton seeds were treated with two previously reported rhizobacterial strains, Pseudomonas fluorescens strain Pf-5 and Bacillus subtilis strain GB03. The efficiency of recovery by each method was determined 3 weeks later by comparing average bacterial populations from whole root systems, single 2.0-cm root segments, and two root regions (the uppermost 5 cm of taproot and the lowermost 5 cm). Treatment with the StomacherR blender yielded significantly higher (P = 0.05) mean populations of GB03 compared with all other methods and significantly higher mean populations of Pf-5 compared with agitation with glass beads. From the lowermost 5 cm of taproot, populations of Pf-5 recovered by the StomacherR treatment were significantly higher than all other methods. The inclusion of glass beads for agitation treatments resulted in neither consistently higher absolute numbers of recovered bacteria nor reductions in variability. The mean standard error of each recovery method varied among root sources, and no single method consistently had the highest or lowest mean standard error. Mean standard errors for strain GB03 were generally lower than those for Pf-5 with each root source and each method of recovery. When viewed in composite, the data suggest that the StomacherR treatment was the best for recovering the greatest absolute numbers of rhizobacteria; however, this treatment had high mean standard errors. Investigations of root colonization by introduced rhizobacteria should include several recovery methods to optimize recovered numbers or to decrease variability, depending on the experimental objectives. Key words: root colonization, rhizobacteria, Pseudomonas fluorescens, Bacillus subtilis, cotton.

scholarly journals A Bacterial Type III Secretion Assay for Delivery of Fungal Effector Proteins into Wheat

2014 ◽  
Vol 27 (3) ◽  
pp. 255-264 ◽  
Author(s):  
Narayana M. Upadhyaya ◽  
Rohit Mago ◽  
Brian J. Staskawicz ◽  
Michael A. Ayliffe ◽  
Jeffrey G. Ellis ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Delivery System ◽  
Type Iii Secretion ◽  
Large Scale ◽  
Rust Fungus ◽  
Effector Proteins ◽  
In Planta ◽  
Host Genotype ◽  
Reporter Protein ◽  
Type Iii

Large numbers of candidate effectors from fungal pathogens are being identified through whole-genome sequencing and in planta expression studies. Although Agrobacterium-mediated transient expression has enabled high-throughput functional analysis of effectors in dicot plants, this assay is not effective in cereal leaves. Here, we show that a nonpathogenic Pseudomonas fluorescens engineered to express the type III secretion system (T3SS) of P. syringae and the wheat pathogen Xanthomonas translucens can deliver fusion proteins containing T3SS signals from P. syringae (AvrRpm1) and X. campestris (AvrBs2) avirulence (Avr) proteins, respectively, into wheat leaf cells. A calmodulin-dependent adenylate cyclase reporter protein was delivered effectively into wheat and barley by both bacteria. Absence of any disease symptoms with P. fluorescens makes it more suitable than X. translucens for detecting a hypersensitive response (HR) induced by an effector protein with avirulence activity. We further modified the delivery system by removal of the myristoylation site from the AvrRpm1 fusion to prevent its localization to the plasma membrane which could inhibit recognition of an Avr protein. Delivery of the flax rust AvrM protein by the modified delivery system into transgenic tobacco leaves expressing the corresponding M resistance protein induced a strong HR, indicating that the system is capable of delivering a functional rust Avr protein. In a preliminary screen of effectors from the stem rust fungus Puccinia graminis f. sp. tritici, we identified one effector that induced a host genotype-specific HR in wheat. Thus, the modified AvrRpm1:effector–Pseudomonas fluorescens system is an effective tool for large-scale screening of pathogen effectors for recognition in wheat.

Strain Diversity of Pseudomonas fluorescens Group with Potential Blue Pigment Phenotype Isolated from Dairy Products

2016 ◽  
Vol 79 (8) ◽  
pp. 1430-1435 ◽  
Author(s):  
MARGHERITA CHIERICI ◽  
CLAUDIA PICOZZI ◽  
MARISA GRAZIA LA SPINA ◽  
CARLA ORSI ◽  
ILEANA VIGENTINI ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Sodium Succinate ◽  
16S Rrna Gene Sequencing ◽  
Pigment Production ◽  
Blue Pigment ◽  
Rrna Gene ◽  
Bacterial Populations ◽  
Strain Diversity ◽  
Blue Discoloration ◽  
Rrna Gene Sequencing

ABSTRACT The blue discoloration in Mozzarella cheese comes from bacterial spoilage due to contamination with Pseudomonas. Fourteen Pseudomonas fluorescens strains from international collections and 55 new isolates of dominant bacterial populations from spoiled fresh cheese samples were examined to assess genotypic and phenotypic strain diversity. Isolates were identified by 16S rRNA gene sequencing and tested for the production of the blue pigment at various temperatures on Mascarpone agar and in Mozzarella preserving fluid (the salty water in which the cheese is conserved, which becomes enriched by cheese minerals and peptides during storage). Pulsed-field gel electrophoresis analysis after treatment with the endonuclease SpeI separated the isolates into 42 genotypes at a similarity level of 80%. Based on the pulsotype clustering, 12 representative strains producing the blue discoloration were chosen for the multilocus sequence typing targeting the gyrB, glnS, ileS, nuoD, recA, rpoB, and rpoD genes. Four new sequence typing profiles were discovered, and the concatenated sequences of the investigated loci grouped the tested strains into the so-called “blue branch” of the P. fluorescens phylogenetic tree, confirming the linkage between pigment production and a specific genomic cluster. Growth temperature affected pigment production; the blue discoloration appeared at 4 and 14°C but not at 30°C. Similarly, the carbon source influenced the phenomenon; the blue phenotype was generated in the presence of glucose but not in the presence of galactose, sodium succinate, sodium citrate, or sodium lactate.

scholarly journals Expression of the gum Operon Directing Xanthan Biosynthesis in Xanthomonas campestris and Its Regulation In Planta

2001 ◽  
Vol 14 (6) ◽  
pp. 768-774 ◽  
Author(s):  
Adrian A. Vojnov ◽  
Holly Slater ◽  
Michael J. Daniels ◽  
J. Maxwell Dow
Keyword(s):  
Xanthomonas Campestris ◽  
Carbon Sources ◽  
Regulatory System ◽  
Extracellular Polysaccharide ◽  
In Planta ◽  
Glucuronidase Activity ◽  
Gum Gene Cluster ◽  
Diffusible Signal Factor ◽  
Turnip Leaves

The gum gene cluster of Xanthomonas campestris pv. campestris comprises 12 genes whose products are involved in the biosynthesis of the extracellular polysaccharide xanthan. These genes are expressed primarily as an operon from a promoter upstream of the first gene, gumB. Although the regulation of xanthan synthesis in vitro has been well studied, nothing is known of its regulation in planta. A reporter plasmid was constructed in which the promoter region of the gum operon was fused to gusA. In liquid cultures, the expression of the gumgusA reporter was correlated closely with the production of xanthan, although a low basal level of β-glucuronidase activity was seen in the absence of added carbon sources when xanthan production was very low. The expression of the gumgusA fusion also was subject to positive regulation by rpfF, which is responsible for the synthesis of the diffusible signal factor (DSF). The expression of the gumgusA fusion in bacteria recovered from inoculated turnip leaves was maximal at the later phases of growth and was subject to regulation by rpfF. These results provide indirect support for the operation of the DSF regulatory system in bacteria in planta.

scholarly journals Regulation of Expression of Avirulence Gene avrRxv and Identification of a Family of Host Interaction Factors by Sequence Analysis of avrBsT

1999 ◽  
Vol 12 (1) ◽  
pp. 35-44 ◽  
Author(s):  
L. D. Ciesiolka ◽  
T. Hwin ◽  
J. D. Gearlds ◽  
G. V. Minsavage ◽  
R. Saenz ◽  
...  
Keyword(s):  
Xanthomonas Campestris ◽  
Inducible Promoter ◽  
Avirulence Gene ◽  
In Planta ◽  
Regulation Of Expression ◽  
Reading Frame ◽  
Pathogen Virulence ◽  
Host Interaction ◽  
Interaction Factor ◽  
Interaction Factors

Resistance in tomato line Hawaii 7998 as well as in several nonhost plants to Xanthomonas campestris pv. vesicatoria tomato strain (XcvT) is mediated in part by the avirulence gene avrRxv. Analysis of growth of wild-type and avrRxv deletion strains indicates that avrRxv plays a crucial role in the ability of XcvT 92–14 to induce resistance on Hawaii 7998. We used avrRxv reporter gene fusions and Northern (RNA) blot analysis to test several growth environments for inductive potential. We found that avrRxv is constitutively expressed at high levels and that growth in planta, in tobacco conditioned medium, and in hrp-inductive medium XVM2 did not affect the high levels of expression. In addition, hrp structural and regulatory mutant backgrounds had no effect. We mutated the bipartite plant inducible promoter (PIP)-box sequence and found that avrRxv activity appears to be independent of an intact PIP-box element. We present the sequence of the avrRxv homologue called avrBsT and align the six AvrRxv host interaction factor family members including mammalian pathogen virulence factors YopJ and YopP from Yersinia spp. and AvrA from Salmonella typhimurium, and open reading frame Y4LO with unknown function from the symbiont Rhizobium sp.

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