Plant- and microbe-derived compounds affect the expression of genes encoding antifungal compounds in a pseudomonad with biocontrol activity.

We have investigated the impacts of 63 different low-molecular-weight compounds, most of them plant derived, on the in vitro expression of two antifungal biosynthetic genes by the plant-protecting rhizobacterium Pseudomonas fluorescens CHA0. The majority of the compounds tested affected the expression of one or both antifungal genes. This suggests that biocontrol activity in plant-beneficial pseudomonads is modulated by plant-bacterium signaling.

(8-Hy-droxy-6-meth-oxy-1-oxo-1H-isochromen-3-yl)methyl formate: a supra-molecular framework.

In the title compound, C12H10O6, an intra-molecular O-H⋯O hydrogen bond forms an S(6) ring motif. The mol-ecule is essentially planar with an r.m.s. deviation of 0.051 Šfor all non-H atoms. In the crystal mol-ecules are linked by C-H⋯O hydrogen bonds and a C-H⋯π inter-action, forming a supra-molecular framework.

The crystal structure, Hirshfeld surface analysis and energy frameworks of 2-[2-(meth-oxy-carbon-yl)-3,6-bis-(meth-oxy-meth-oxy)phen-yl]acetic acid.

In the title compound, C14H18O8, (I), the meth-oxy-carbonyl [-C(=O)OCH3] and the acetic acid [-CH2C(=O)OH] groups are inclined to the benzene ring by 79.24 (11) and 76.71 (13)°, respectively, and are normal to each other with a dihedral angle of 90.00 (13)°. In the crystal, mol-ecules are linked by a pair of O-H⋯O hydrogen bonds forming the familiar acetic acid inversion dimer. The dimers are linked by two C-H⋯O hydrogen bonds and an offset π-π inter-action [inter-centroid distance = 3.6405 (14) Å], forming layers lying parallel to the (10) plane. The layers are linked by a third C-H⋯O hydrogen bond and a C-H⋯π inter-action to form a supra-molecular framework.

Crystal structures and Hirshfeld surface analyses of 6,8-dimeth-oxy-3-methyl-1H-isochromen-1-one and 5-bromo-6,8-dimeth-oxy-3-methyl-1H-isochromen-1-one chloro-form monosolvate.

In the mol-ecule of 6,8-dimeth-oxy-3-methyl-1H-isochromen-1-one, C12H12O4, (I), the two meth-oxy groups are directed anti with respect to each other. In the mol-ecule of the brom-inated derivative, 5-bromo-6,8-dimeth-oxy-3-methyl-1H-isochromen-1-one, that crystallized as a chloro-form monosolvate, C12H11BrO4·CHCl3, (II·CHCl3 ), the meth-oxy groups are directed syn to each other. In the crystal of I, mol-ecules are linked by bifurcated C-H⋯O hydrogen bonds, forming chains along the c-axis direction. The chains are linked by C-H⋯π inter-actions, forming a supra-molecular framework. In the crystal of II·CHCl3 , mol-ecules are linked by C-H⋯O hydrogen bonds forming 21 helices parallel to the b-axis direction. The chloro-form solvate mol-ecules are linked to the helices by C-H⋯O(carbon-yl) hydrogen bonds. The helices stack up the c-axis direction and are linked by offset π-π inter-actions [inter-centroid distance = 3.517 (3) Å], forming layers parallel to the (100) plane. Compound II·CHCl3 was refined as a two-component twin. Two chlorine atoms of the chloro-form solvate are disordered over two positions and were refined with a fixed occupancy ratio of 0.5:0.5.

The crystal structure and Hirshfeld surface analysis of 1-(2,5-di-meth-oxy-phen-yl)-2,2,6,6-tetra-methyl-piperidine.

In the title compound, C17H27NO2, the piperidine ring has a chair conformation and is positioned normal to the benzene ring. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming chains propagating along the c-axis direction.

Bafoudiosbulbins A, and B, two anti-salmonellal clerodane diterpenoids from Dioscorea bulbifera L. var sativa.

Two clerodane diterpenoids, Bafoudiosbulbins A 1, and B 2, together with five known compounds: tetracosanoic acid, 1-(tetracosanoyl)-glycerol, trans-tetracosanylferulate, beta-sitosterol and 3-O-beta-D-glucopyranosyl-beta-sitosterol were isolated from the tubers of Dioscorea bulbifera L. var sativa. Their structures were established by spectroscopic methods (1D and 2D-NMR, MS) and X-ray crystallographic diffraction analysis of compound 1. The CH2Cl2-soluble portion of the crude extract and the two clerodanes were screened for anti-bacterial activity using both agar diffusion and broth dilution techniques against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella typhi, Salmonella paratyphi A and Salmonella paratyphi B. They both showed significant activities against P. aeruginosa, S. typhi, S. paratyphi A and S. paratyphi B.

Transformation of Eutypa dieback and esca disease pathogen toxins by antagonistic fungal strains reveals a second detoxification pathway not present in Vitis vinifera.

Eutypine, 4-hydroxybenzaldehyde, and 3-phenyllactic acid are some of the phytotoxins produced by the pathogens causing Eutypa dieback and esca disease, two trunk diseases of grapevine (Vitis vinifera). Known biocontrol agents such as Fusarium lateritium and Trichoderma sp. were screened for their ability to consume these toxins. Transformation time courses were performed, and an high-performance liquid chromatography-based method was developed to analyze toxin metabolism and to identify and quantify the converted products. The results show that the aldehyde function of eutypine was reduced to eutypinol, as by V. vinifera cv. Merlot, the cultivar tolerant to Eutypa dieback. We revealed a supplementary detoxification pathway, not known in Merlot, where the aldehyde function was oxidized to eutypinic acid. Moreover, some strains tested could further metabolize the transformation products. Every strain tested could transform 4-hydroxybenzaldehyde to the corresponding alcohol and acid, and these intermediates disappeared totally at the end of the time courses. When biological assays on cells of V. vinifera cv. Chasselas were carried out, the transformation products exhibited a lower toxicity than the toxins. The possibility of selecting new biocontrol agents against trunk diseases of grapevine based on microbial detoxification is discussed.

Differential production of phytotoxins from Phomopsis sp. from grapevine plants showing esca symptoms.

Nine strains of the fungus Phomopsis spp. were isolated from a vineyard showing decline from the disease esca. Strains were screened for their ability to produce secondary metabolites showing chemical diversity. The culture extracts of each strain were analyzed by liquid chromatography-ultraviolet-diode array detection-mass spectrometry. Three strains were selected for the isolation and characterization of eight of the major metabolites. Structures were elucidated by spectroscopic analyses including two-dimensional NMR and mass spectrometry and by comparison to literature data. Among the isolated metabolites were the known phomopsolide B (1), sydowinin A (6), sydowinol (7), cytosporone B (8), and four new furanones named phomopsolidones A-D (2-5). The fungal strains were identified as Phomopsis sp., Phomopsis viticola Sacc and, Phomopsis viticola complex. Biological assays on Vitis vinifera leaves and callus tissue, antibacterial, and insecticidal activities were evaluated. The results revealed variability regarding secondary metabolites with species of Phomopsis sp. associated with grapevine, raising the question of cultivar-driven strain selection and phytotoxins biosynthesis in grapevine plants.

Fractionation of grape tannins and analysis by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.

Polymeric tannins, extracted from grape berries (Gamay variety), were fractionated according to their mean degree of polymerisation (mDP) on a styrene-divinylbenzene phase eluted with a gradient of methanol:chloroform. Increasing the percentage of methanol led to the solubilisation of higher molecular weight tannins. The mean mDP of each collected fraction was determined by acid-catalysed degradation in the presence of a nucleophilic reagent. The fractionation method produced a linear gradient of mDP varying between 1.84 and 19.34. The fractions were partially characterised by matrix assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). The spectra showed a complex mixture of proanthocyanidins and galloylated proanthocyanidins up to 4000 amu.