Pseudomonas Phaseolicola Research Articles

Antimicrobial flavonoids from the twigs of Populus nigra × Populus deltoides

A bioassay-guided fractionation of the ethyl acetate extract from the twigs of the hybrid poplar ‘Neva’, Populus nigra L. × Populus deltoides Marsh, led to the isolation of three flavonoids, which were identified by means of spectrometric and physicochemical analysis as 5-hydroxy-7-methoxy-flavone (1), 5,7-dihydoxy-flavone (2) and 5,7-dihydroxy-flavonol (3). These compounds were further screened for their antimicrobial activity against plant pathogens, including three bacteria (Pseudomonas lachrymans, Ralstonia solanacearum and Xanthomonas vesicatoria) and one fungus (Magnaporthe oryzae). Compounds 2 and 3 showed significant antibacterial activity, with minimum inhibitory concentrations (MICs) ranging from 15 to 25 µg mL−1, and median inhibitory concentrations (IC50 values) from 4 to 18 µg mL−1. The results obtained provide promising baseline information for the potential use of the extract and flavonoids from this plant as antimicrobial agents to help control plant diseases.

Detection of bacterial aggregation in tobacco cell suspensions treated with pathogenic bacteria

Previous studies of this model system involving plant cell suspensions inoculated with bacteria, have documented that interactions with incompatible pathogens, which cause a hypersensitive response on whole plants, will cause a transient increase in oxygen uptake 2–4 h after inoculation. The initial objective of this study was to determine whether this oxygen uptake burst was a result of increased bacterial multiplication, possibly due to nutrient leakage from plant cells. The adaptation of flow cytometry and the use of fluorescent nucleic acid stains provided the precision needed to monitor bacterial concentrations in tobacco suspension cells inoculated with pathogenic and non-pathogenic Pseudomonas species. Surprisingly, there was a transient decrease in the planktonic, or free-living, bacteria in cell suspensions inoculated with isolate Pseudomonas syringae pv. syringae WT (HR+), an incompatible pathogen of tobacco. This decrease in planktonic numbers was followed by an apparent increase in bacterial multiplication. Examination of the samples with fluorescent microscopy revealed the formation of bacterial aggregates in the extracellular fluid of the Pss WT (HR+) inoculated plant cells. The size of the aggregates increased at the onset of the oxygen uptake response, and contained increasing numbers of bacterial cells. These aggregated bacterial cells appear to be removed along with plant cells, as a result of filtration during sample preparation, causing the apparent decrease in planktonic bacteria detected by flow cytometry. This bacterial aggregation was also observed with the compatible Pseudomonas tabaci pathogen, which does not induce a noticeable oxygen uptake burst. No aggregation was observed with suspension inoculated with Pseudomonas fluorescens, a saprophyte, or Pss B7 (HR−), a Tn5 mutant of P. s. syringae. This aggregation response was rapid, once initiated, and appeared similar to reports of adhesion involving Hrp pili.

Diagnosis and detection of the main bacterial pathogens of stone fruit and almond

SUMMARY Diagnosis and detection are key aspects related to plant health status. A critical review of the available diagnostic methods utilised for Agrobacterium rhizogenes and A. tumefaciens, Pseudomonas amygdali, P. syringae pv. mors-prunorum, P. syringae pv. persicae, P. syringae pv. syringae and Xanthomonas arboricola pv. pruni, the main pathogens of the stone fruit trees, is presented. As there is a general lack of updated standardized protocols for the detection of most of these bacteria, the most appropriate media for their isolation are reported along with serological reagents, PCR and real-time PCR protocols with comments on their accuracy for the analysis of these pathogens in plant samples. There are many selective media for isolation, especially for Agrobacterium spp., but fewer for Pseudomonas spp. and X. arboricola pv. pruni. Serological techniques are not very useful for these pathogens due to the current lack of specific antibodies commercially available. As to molecular methods, it is surprising to find so many PCR protocols for Agrobacterium species, very few and unspecific for the Pseudomonas species pathogenic to stone fruit trees, and several recent PCR protocols for X. arboricola pv. pruni. The new advances in genomics and proteomics will provide information for selecting new targets to develop specific and sensitive techniques for the diagnosis and detection of these bacterial pathogens in plant material.

Phage induction by UV and mitomycin C in Pseudomonas mori, the pathogen of bacterial blight of mulberry

Phage induction by UV and mitomycin C in Pseudomonas mori, the pathogen of bacterial blight of mulberry

Synthesis and antimicrobial activity of some new thiazole, thiophene and pyrazole derivatives containing benzothiazole moiety

In an attempt to find a new class of antimicrobial agents, a series of thiazole, thiophene, pyrazole and other related products containing benzothiazole moiety were prepared via the reaction of N-(benzothiazol-2-yl)-2-cyanoacetamide ( 1) with appropriate chemical reagents. These compounds were screened for their antibacterial activity against Gram-positive bacteria ( Staphylococcus aureus and Streptococcus pyogenes), Gram-negative bacteria (Pseudomonas phaseolicola and Pseudomonas fluorescens) and antifungal activity against Fusarium oxysporum and Aspergillus fumigatus. Among the synthesized compounds, thiophene 13 showed equal activity with chloroamphenicol against S. aureus (MIC 3.125 μg/mL), while its activity was 50% lower than of chloroamphenicol against S. pyogenes. Thiazole 3 and pyrazolo[1,5- a]pyrimidine 21b were found to exhibit the most potent in vitro antifungal activity with MICs (6.25 μg/mL) against A. fumigatus and F. oxysporum. Structures of the newly synthesized compounds were established by elemental analysis and spectral data.

Structural, spectral and biological studies of binuclear tetradentate metal complexes of N 3O Schiff base ligand synthesized from 4,6-diacetylresorcinol and diethylenetriamine

The binuclear Schiff base, H 2L, ligand was synthesized by reaction of 4,6-diacetylresorcinol with diethylenetriamine in the molar ratio 1:2. The coordination behavior of the H 2L towards Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cr(III), VO(IV) and UO 2(VI) ions has been investigated. The elemental analyses, magnetic moments, thermal studies and IR, electronic, 1H NMR, ESR and mass spectra were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with two N 3O-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The bonding sites are the nitrogen atoms of the azomethine and amine groups and the oxygen atoms of the phenolic groups. The metal complexes exhibit either square planar, tetrahedral, square pyramid or octahedral structures. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria ( Staphylococcus aureus and Streptococcus pyogenes) as Gram-positive bacteria, and ( Pseudomonas fluorescens and Pseudomonas phaseolicola) as Gram-negative bacteria and two pathogenic fungi ( Fusarium oxysporum and Aspergillus fumigatus) to assess their antimicrobial properties. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

Beauvericin from the Endophytic Fungus, Fusarium redolens, Isolated from Dioscorea zingiberensis and Its Antibacterial Activity

From the fungal endophyte, Fusarium redolens Dzf2, isolated from rhizomes of the Chinese medicinal plant Dioscorea zingiberensis, beauvericin was obtained by TLC in combination with bioautographic antibacterial assay. The compound was identified by spectroscopic and physicochemical means. The median effective inhibitory concentration (IC50) values of beauvericin against six test bacteria (Bacillus subtilis, Staphylococcus haemolyticus, Pseudomonas lachrymans, Agrobacterium tumefaciens, Escherichia coli and Xanthomonas vesicatoria) were between 18.4 and 70.7 microg/mL. The beauvericin content of F. redolens Dzf2 mycelia was 9.60 mg/g dw, and beauvericin yield 62.4 mg/L. The obtained results show the potential use of the endophytic fungus for its biological role in providing its host plant with protection, as well as the possible development of beauvericin as an antibacterial.

Synthesis, spectral studies, and antimicrobial activity of binary and ternary Cu(II), Ni(II), and Fe(III) complexes of new hexadentate Schiff bases derived from 4,6-diacetylresorcinol and amino acids

Two new hexadentate N2O4 donor Schiff bases, H4L1 and H4L2, were synthesized by condensation of 4,6-diacetylresorcinol with glycine and alanine, respectively. The structures of the ligands were elucidated by elemental analyses, IR, 1H NMR, electronic, and mass spectra. Reactions of the Schiff bases with copper(II), nickel(II), and iron(III) nitrates in 1 : 2 molar ratio gave binuclear metal complexes and, in the presence of 8-hydroxyquinoline (8-HQ) or 1,10-phenanthroline (Phen) as secondary ligands (L′), mixed-ligand complexes in two molar ratios 1 : 2 : 2 and 1 : 2 : 1 (L1/L2 : M : L′). The complexes were characterized by elemental and thermal analyses, IR, electronic, mass, and ESR spectral studies, as well as conductivity and magnetic susceptibility measurements. The spectroscopic data reveal that the Schiff-base ligands were dibasic or tetrabasic hexadentate ligands. The coordination sites with the metal ions are two azomethine nitrogens, two oxygens of phenolic groups, and two oxygens of carboxylic groups. Copper(II) complexes were octahedral and square planar while nickel(II) and iron(III) complexes were octahedral. The Schiff bases, H4L1 and H4L2, and some of their metal complexes showed antibacterial activity towards Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Pseudomonas fluorescens and Pseudomonas phaseolicola) bacteria and antifungal activity towards the fungi Fusarium oxysporium and Aspergillus fumigatus.

Synthesis, spectroscopic investigations, and biological activity of metal complexes of N-benzoylthiosemicarbazide

N-Benzoylthiosemicarbazide, HL, was obtained by fusion of benzoylhydrazide and ammonium thiocyanate. Reactions of HL with cobalt(II), nickel(II), copper(II), zinc(II), iron(III), cadmium(II), oxovanadium(IV), and dioxouranium(VI) in 1 : 1 molar ratio yield the corresponding complexes. The N-benzoylthiosemicarbazide may act as a neutral or monobasic bidentate ligand coordinated through NS or NO sites. The structures of the HL ligand and its complexes were identified by elemental analysis, infrared, electronic, mass, 1H-NMR, and ESR spectra as well as magnetic susceptibility and molar conductivity measurements. Different geometries were obtained for the metal complexes. The ligand and its metal complexes were investigated for antibacterial and antifungal properties. Two Gram-positive bacteria, Staphylococcus aureus and Streptococcus pyogenes, two Gram-negative, bacteria, Pseudomonas fluorescens and Pseudomonas phaseolicola and two fungi, Fusarium oxysporum and Aspergillus fumigatus, were used in this study. The metal complexes were more effective than the free ligand.

Antimicrobial Phenolic Compounds from Anabasis Aphylla L

Bioassay-guided fractionation of an ethyl acetate extract from the aerial parts of Anabasis aphylla, a Chenopodiaceous species widely distributed in the northwest of China, led to the isolation of six phenolic compounds, which were identified by means of spectrometric analysis as 1-(2-hydroxy-4,6-dimethoxyphenyl)-ethanone (1), 3,4-dihydroxy cinnamic acid tetracosyl ester (2), 4-hydroxy-3-methoxy benzoic acid (3), 2-hydroxy benzoic acid (4), 3,4-dihydroxy cinnamic acid methyl ester (5) and 4-hydroxy benzoic acid pentadecane ester (6). These compounds were further screened for their minimum inhibitory concentration (MIC) and median inhibitory concentration (IC50) by use of the micro-dilution-MTT assay for antimicrobial activity against one Gram-positive bacterium (Bacillus subtilis), three Gram-negative bacteria (Agrobacterium tumefaciens, Pseudomonas lachrymans, and Xanthomonas vesicatoria), and one yeast (Candida albicans). Apart from compound 6, which had no activity against any of the tested microorganisms, the other compounds showed selective inhibitory activity. This is the first report on the antimicrobial activity of the phenolic compounds isolated from A. aphylla. The obtained results provide promising baseline information for the potential use of the extract and some isolated compounds from this plant as antimicrobial agents to control plant and animal diseases.

Mixed ligand complexes of nickel(II) and cerium(III) ions with 4-(-3-methoxy-4-hydroxybenzylideneamino)-1, 3-dimethyl-2,6-pyrimidine-dione and some nitrogen/oxygen donor ligands

Mononuclear mixed ligand complexes of Ni(II) and Ce(III) with 4-(-3-methoxy-4-hydroxybenzylideneamino)-1,3-dimethyl-2,6-pyrimidine-dione, 2-aminopyridine and 8-hydroxyquinoline have been prepared. The elemental analysis, molar conductance, spectral (IR, mass and solid reflectance), magnetic moment measurements and thermal study were utilized to investigate the coordination behavior. All metal complexes have metal-to-ligand ratios of 1:1:1 and the modes of bonding are consistent with N- and O-donation suggesting monomeric octahedral and square planar structures. The thermal behavior of these complexes was investigated and the thermal decomposition pathways postulated. The activation thermodynamic parameters, E*, ΔH*, ΔS* and ΔG* for the different thermal decomposition steps of the complexes were calculated using the Coats-Redfern equation. Antibacterial and antifungal properties of the metal complexes have also been examined against Staphylococcus aureus (ATCC 25923), Streptococcus pyogenes (ATCC 19615), Pseudomonas fluorescens (S 97), Pseudomonas phaseolicola (GSPB 2828), Fusarium oxysporum and Aspergillus fumigatus. The highest antimicrobial activity was observed for the Ce(III) complex, [CeL(8-Oqu)(NO3)2]·1½H2O.

A new form of general disease reisstance associated with host cell proliferation

We have found a form of resistance lacking host cell death, effective in cucumber against infection of Pseudoperonospora cubensis , in bean against Pseudomonas phaseolicola and Xanthomonas phaseoli , as well as in pepper against the Obuda pepper virus and Xanthomonas vesicatoria . In addition to the own pathogens of the host plants, this defense reaction, accompanied by cell enlargement and stimulated cell division, was also efficient against pathogen species that are in incompatible relationship with the given host plants (the nonhosts). This general defense reaction may manifest itself in different intensities: in cell enlargement of only a few plant cells or enlargement and proliferation of cells to such a degree that results in compaction of even larger tissue parts.

Chemical Composition and Antimicrobial Activity of the Flower Oil of Russowia sogdiana (Bunge) B. Fedtsch. (Asteraceae) from China

An essential oil, which was obtained by water distillation from Russowia sogdiana (Bunge) B. Fedtsch. flowers, was analyzed by GC and GC/MS. The main constituents were identified as limonene (15.9%), trans-α-bergamotene (5.6%), salvial-4(14)-en-1-one (3.8%), carvone (3.6%), p-cymene (3.6%), trans -carveol (3.2%). Thirty-two components were separated and identified which accounted for over 62.1% of the total essential oil. The antimicrobial activity of R. sogdiana oil was studied using broth dilution test on seven bacterial strains, using mycelial growth test on three fungal strains. The oil exhibited a broad spectrum antibacterial activity against Gram-positive (Bacillussubtilis, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Erwinia carotovora ssp. carotovora, Pseudomonas lachrymans, Xanthomonas vesicatoria, Agrobacterium tumefaciens) with minimum inhibitory concentration (MIC) values ranging from 0.2 mg/mL to 0.8 mg/mL. The oil also showed an important antifungal activity against fruit pathogenic fungi Glomerella cingulata, Botryodiplodia theobromea and Venturia pirina. Maximum antifungal activity was observed against G. cingulata mycelial growth which percentage inhibition was 51.8% at concentration of 100 μg/mL.

Pseudomonas syringae Diseases of Fruit Trees: Progress Toward Understanding and Control.

Pseudomonas syringae Diseases of Fruit Trees: Progress Toward Understanding and Control.

Antimicrobial activity of the hypercum perforatum l. plant

The goal of this study was to determine the level of antimicrobial activity of ethanolic extract of St. John's wort ( H. perforatum L. ) toward some phytopathogenic bacteria and fungi. The fungi Fusarium oxysporum (Schlecht) and Penicillium canescens (Sopp) were isolated from fruit which was in a process of deterioration. The antifungal activity of the ethanolic extract with concentration of 5–45 mg/ml in the period of 72 hours, was determined by the method of spore counting (Nauber’s chamber). It was concluded that the sample with 45 mg/ml of ethanolic extract of H. perforatum showed most fungistaticity. When 1·10 2 spores of fungi were inoculated, the number of spores was decreased to 5 spores for F. oxysporum, and to 15 spores for P. canescens . The bacteria Pseudomonas glycinea and Azotobacter chrococcum showed extreme sensitivity to the presence of 25 mg of the extract of H. perforatum. Bacterial growth was inhibited by 53 %. Higher degree of resistance to the extract of H. perforatum was demonstrated by the bacteria Bacillus subtilis. With 25 mg of extract per disc, an inhibition of 25 % was observed, but with 5 mg extract, an inhibition of 1.8 % was detected. The minimum inhibition concentration of ethanolic extract of H. perforatum depends on the phytopathogenic bacteria type (G+, G–), and varies between 1.25–3.5 mg/ml.

Involvement of acetosyringone in plant–pathogen recognition

In this study, acetosyringone was identified as one of the major extracellular phenolics in tobacco suspension cells and was shown to have bioactive properties that influence early events in plant–bacterial pathogenesis. In our model system, tobacco cell suspensions treated with bacterial isolate Pseudomonas syringae WT (HR+) undergo a resistant interaction characterized by a burst in oxygen uptake several hours after inoculation. When the extracellular concentration of acetosyringone in tobacco cell suspensions was supplemented with exogenous acetosyringone, the burst in oxygen uptake occurred as much as 1.5 h earlier. The exogenous acetosyringone had no effect on tobacco suspensions undergoing susceptible interactions with Pseudomonas tabaci or a non-resistant interaction with a near-isogenic mutant derivative of isolate P. syringae WT (HR+). Resistant interactions with isolate P. syringae WT (HR+) also produce an oxidative burst which oxidizes the extracellular acetosyringone. This study demonstrates that acetosyringone, and likely other extracellular phenolics, may have bioactive characteristics that can influence plant–bacterial pathogenesis.

Reduced fecundity is the cost of cheating in RNA virusϕ6

Co-infection by multiple viruses affords opportunities for the evolution of cheating strategies to use intracellular resources. Cheating may be costly, however, when viruses infect cells alone. We previously allowed the RNA bacteriophage phi6 to evolve for 250 generations in replicated environments allowing co-infection of Pseudomonas phaseolicola bacteria. Derived genotypes showed great capacity to compete during co-infection, but suffered reduced performance in solo infections. Thus, the evolved viruses appear to be cheaters that sacrifice between-host fitness for within-host fitness. It is unknown, however, which stage of the lytic growth cycle is linked to the cost of cheating. Here, we examine the cost through burst assays, where lytic infection can be separated into three discrete phases (analogous to phage life history): dispersal stage, latent period (juvenile stage), and burst (adult stage). We compared growth of a representative cheater and its ancestor in environments where the cost occurs. The cost of cheating was shown to be reduced fecundity, because cheaters feature a significantly smaller burst size (progeny produced per infected cell) when infecting on their own. Interestingly, latent period (average burst time) of the evolved virus was much longer than that of the ancestor, indicating the cost does not follow a life history trade-off between timing of reproduction and lifetime fecundity. Our data suggest that interference competition allows high fitness of derived cheaters in mixed infections, and we discuss preferential encapsidation as one possible mechanism.

Antimicrobial activities of constituents from isolona cauliflora verdc and cleistochlamys krikii benth, oliv.: Annonaceae

Antimicrobial activities of crude extract, Caulindole D, a mixture of Caulindole E and F, Pinocembrin and an Oxyheptanoid (Clestochlamic acid) from stem bark of Isolona cauliflora and Cleistochlamys krikii on Pseudomonas phaseolicola, Fusarium solani, Botryodiploida theobromae Aspergillus niger and Aspergillus flavus have been investigated. An in vitro bioassay test showed that the crude dichloro-methane extract from C. krikii and a very strong antimicrobial property. The pure compound had strong to moderate inhibitory effect on Pseudomonas syringae pv. phaseolicola and Botryodiplodia theobromae. The pure compounds from Cleistochlamus krikii had more pronounced inhibitory activities than the pure compounds from Isola cauliflora. At lower concentration of 100-200 ppm, the crude extract of Caulindole, mixture of Caulindole E and F, Pinocembrion and Oxyheptanoid had effect on most of the investigated plant pathogens. Higher concentration of 500-1000 ppm had moderate to weak effect on the Aspergillus spp.

The Formation of Test Arrays and a Core Collection in Cucumber Using Phenotypic and Molecular Marker Data

Genetic relationships among 970 cucumber (Cucumis sativus L.) plant introductions (PIs) in the U.S. National Plant Germplasm System (NPGS) were assessed by observing variation at 15 isozyme loci. Allozyme frequency data for these PIs were compared to allozyme variation in heirloom and modern (H&M) cultivars released from 1846-1985 (H&M cultivars; 178 accessions), and experimental commercial (EC) germplasm (EC germplasm; 82 accessions) in use after 1985. Multivariate analysis defined four distinct groups of accessions (Groups A-D), where Group A consisted of PIs received by the NPGS before 1992, Group B contained PIs from India and China obtained by NPGS after 1992, Group C consisted of EC germplasm, and Group D contained H&M cultivars. Morphological, abiotic stress (water and heat stress tolerance) and disease resistance evaluation data from the Germplasm Resources Information Network (GRIN) for the PIs examined were used in conjunction with estimates of population variation and genetic distance estimates to construct test arrays and a core collection for cucumber. Disease resistance data included the evaluation of angular leafspot [Pseudomonas lachrymans (E.F. Smith) Holland], anthracnose [Colletotrichum lagenarium (Ross.) Ellis & Halst], downy mildew [Pseudoperonospora cubensis (Berk. & Curt) Rostow], rhizoctonia fruit rot (Rhizoctonia solani Kuhn), and target leafspot [Corynespora cassiicola (Berk. & Curt) Wei] pathogenicity. The test arrays for resistance-tolerance to angular leafspot, anthracnose, downy mildew, rhizoctonia fruit rot, target leafspot, and water and heat stress consisted of 17, 16, 17, 16, 17, 16, and 16 accessions, respectively. The core collection consisted of accessions in these test arrays (115) and additional 32 accessions that helped circumscribe the genetic diversity of the NPGS collection. The core collection of 147 accessions (115 + 32) represents ≈11% of the total collection's size (1352). Given estimates of genetic diversity and theoretical retention of diversity after sampling, this core collection could increase curatorial effectiveness and the efficiency of end-users as they attempt to identify potentially useful germplasm.

Isolation and Characterization of the algD gene of Pseudomonas syringae pv. phaseolicola and its distribution among other Pseudomonads and related Organisms

The gene coding for GDP‐mannose dehydrogenase (algD) was isolated from a Pseudomonas syringae pv. phaseolicola genomic library using a polymerase chain reaction‐generated heterologous DNA‐probe from Pseudomonas aeruginosa. A total of 2123 base pairs were sequenced (accession number AF001555) and analysed for homologies to the alginate gene cluster of P. aeruginosa. Downstream from algD an alg8 homologue was found suggesting a similar arrangement of the alginate gene cluster in P. syringae pv. phaseolicola to that in P. aeruginosa. Also, the deduced amino acid sequence of algD shows high similarity to that of P. aeruginosa (0.9) and Azotobacter vinelandii (0.88). Southern hybridization experiments revealed that algD is widely distributed among members of the Pseudomonas rRNA homology group I. Among others, sequences homologous to algD were detected in the P.syringae pathovars lachrymans, mori, morsprunorum,pisi, savastanoi, tabaci and tomato as well as in Pseudomonas amygdali. For most of the algD positive organisms synthesis of alginate has been reported by other studies. However, algD homologues were also detected for the species Pseudomonas corrugata, Pseudomonas marginalis and Pseudomonas avenae (Acidovorax avenae), for which alginate biosynthesis has not yet been reported.