Impact of bacterial volatiles on phytopathogenic fungi: an in vitro study on microbial competition and interaction.

Microorganisms in the rhizosphere are abundant and exist in very high taxonomic diversity. The major players are bacteria and fungi, and bacteria have evolved many strategies to prevail over fungi, among them harmful enzyme activities and noxious secondary metabolites. Interactions between plant growth promoting rhizobacteria and phytopathogenic fungi are potentially valuable since the plant would benefit from fungal growth repression.

Publisher Correction: Interspecific formation of the antimicrobial volatile schleiferon.

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Interspecific formation of the antimicrobial volatile schleiferon.

Microorganisms release a plethora of volatile secondary metabolites. Up to now, it has been widely accepted that these volatile organic compounds are produced and emitted as a final product by a single organism e.g.

The α-Terpineol to 1,8-Cineole Cyclization Reaction of Tobacco Terpene Synthases.

Flowers of Nicotiana species emit a characteristic blend including the cineole cassette monoterpenes. This set of terpenes is synthesized by multiproduct enzymes, with either 1,8-cineole or α-terpineol contributing most to the volatile spectrum, thus referring to cineole or terpineol synthase, respectively. To understand the molecular and structural requirements of the enzymes that favor the biochemical formation of α-terpineol and 1,8-cineole, site-directed mutagenesis, in silico modeling, and semiempiric calculations were performed.

Bacterial-Plant-Interactions: Approaches to Unravel the Biological Function of Bacterial Volatiles in the Rhizosphere.

Rhizobacteria produce an enormous amount of volatile compounds, however, the function of these metabolites is scarcely understood. Investigations evaluating influences on plants performed in various laboratories using individually developed experimental setups revealed different and often contradictory results, e.g.

Volatile mediated interactions between bacteria and fungi in the soil.

Soil is one of the major habitats of bacteria and fungi. In this arena their interactions are part of a communication network that keeps microhabitats in balance. Prominent mediator molecules of these inter- and intraorganismic relationships are inorganic and organic microbial volatile compounds (mVOCs).

SuperScent--a database of flavors and scents.

Volatiles are efficient mediators of chemical communication acting universally as attractant, repellent or warning signal in all kingdoms of life. Beside this broad impact volatiles have in nature, scents are also widely used in pharmaceutical, food and cosmetic industries, so the identification of new scents is of great industrial interest. Despite this importance as well as the vast number and diversity of volatile compounds, there is currently no comprehensive public database providing information on structure and chemical classification of volatiles.

Influence of green leaf herbivory by Manduca sexta on floral volatile emission by Nicotiana suaveolens.

Plants have to cope with various abiotic and biotic impacts as a consequence of changing environments, which can impair their ability to sexually reproduce. The main objective of this study was to investigate whether green leaf herbivory, having one of the most hazardous biotic impacts, would have any direct effect on the production and emission of floral volatiles because volatiles are known to play a crucial role in pollination. Nicotiana suaveolens plants were challenged with Manduca sexta feeding on leaves, and alterations in the quality and quantity of the floral blend, shifts in emission patterns, and changes in expression patterns of the floral benzoic/salicylic acid carboxyl-methyltransferase were monitored in noninfested and infested plants.

Regulation of simultaneous synthesis of floral scent terpenoids by the 1,8-cineole synthase of Nicotiana suaveolens.

The white flowers of N. suaveolens emit a complex bouquet of fragrance volatiles. The dominant compounds are benzenoids (e.

Volatiles of bacterial antagonists inhibit mycelial growth of the plant pathogen Rhizoctonia solani.

Bacterial antagonists are bacteria that negatively affect the growth of other organisms. Many antagonists inhibit the growth of fungi by various mechanisms, e.g.

Localization of methyl benzoate synthesis and emission in Stephanotis floribunda and Nicotiana suaveolens flowers.

The emission of fragrances can qualitatively and quantitatively differ in different parts of flowers. A detailed analysis was initiated to localize the floral tissues and cells which contribute to scent synthesis in STEPHANOTIS FLORIBUNDA (Asclepiadaceae) and NICOTIANA SUAVEOLENS (Solanaceae). The emission of scent compounds in these species is primarily found in the lobes of the corollas and little/no emission can be attributed to other floral organs or tissues.

Effects of phytoestrogen extracts isolated from rye, green and yellow pea seeds on hormone production and proliferation of trophoblast tumor cells Jeg3.

Background: Phytoestrogens are a diverse group of non-steroidal plant compounds. Because they have chemical structures similar to estrogens they are able to bind on estrogen receptors in humans.

Objectives: In this study, we tested the effects of crude phytoestrogen extracts from rye (Secale cereale), green pea (Pisum sativum) and yellow pea seeds (Pisum sativum cv.

Flax-seed extracts with phytoestrogenic effects on a hormone receptor-positive tumour cell line.

Unlabelled: The higher soy intake in the Asian population compared to Europeans is believed to be an essential factor for the lower incidence of hormone-dependent tumours in Asia. It has already been shown that soya beans, with their ingredients genistein and daidzein from the isoflavonoid group, have protective effects on hormone-caused diseases. Lignans are another, less investigated, group of phytoestrogens.

Floral benzenoid carboxyl methyltransferases: from in vitro to in planta function.

Benzenoid carboxyl methyltransferases synthesize methyl esters (e.g., methyl benzoate and methyl salicylate), which are constituents of aromas and scents of many plant species and play important roles in plant communication with the surrounding environment.

Volatile composition, emission pattern, and localization of floral scent emission in Mirabilis jalapa (Nyctaginaceae).

We elucidated scent components, daily emission patterns, and the localization of floral scent release of Mirabilis jalapa. Volatiles emitted by the whole plant as well as by detached flowers were investigated using dynamic headspace analysis and gas chromatography/ mass spectrometry. Among several constituents including (Z)-3-hexenyl acetate, β-myrcene, (Z)-ocimene, and benzyl benzoate, the monoterpene (E)-β-ocimene was the major fragrance component.

Biochemical and structural characterization of benzenoid carboxyl methyltransferases involved in floral scent production in Stephanotis floribunda and Nicotiana suaveolens.

Flower-specific benzenoid carboxyl methyltransferases from Stephanotis floribunda and Nicotiana suaveolens were biochemically and structurally characterized. The floral scents of both these species contain higher levels of methyl benzoate and lower levels of methyl salicylate. The S.

Transcriptional and post-translational regulation of S-adenosyl-L-methionine: salicylic acid carboxyl methyltransferase (SAMT) during Stephanotis floribunda flower development.

Methyl salicylate (MeSA) and a number of other volatiles are primarily emitted in the evening/night by Stephanotis floribunda leading to attraction of night active pollinators. A second minor emission peak for MeSA occurs in the morning/day. To understand these emission patterns, we have studied in detail the temporal regulation of the last step of the biosynthetic pathway of MeSA, the convertion of salicylic acid (SA) to MeSA catalysed by S-adenosyl-L-methionine: salicylic acid carboxyl methyltransferase (SAMT).

Biochemical characterization of glucosylglycerol-phosphate synthase of Synechocystis sp. strain PCC 6803: comparison of crude, purified, and recombinant enzymes.

Glucosylglycerol-phosphate synthase (GGPS), the key enzyme of the glucosylglycerol biosynthesis in salt-stressed cells of Synechocystis, was biochemically analyzed in crude extracts, after partial purification by FPLC and after overexpression of the gene ggpS in Escherichia coli and purification to homogenity of the recombinant protein, respectively. These GGPS preparations behaved similarly with regard to temperature stability, pH optimum, Mg2+ dependence, inhibition by phosphates, and Km values, but differed in their dependence on NaCl concentration: crude enzyme needed activation by addition of NaCl, whereas both partially-purified and recombinant GGPS showed high activities independent of the NaCl concentration.

Biochemical and pharmacological investigations of selected cyanobacteria.

Cyanobacteria are a very old group of prokaryotic organisms that produce a variety of secondary metabolites with antibiotic, algicide, cytotoxic, immunosuppressive and enzyme inhibiting activities. In the last decades structures of pure compounds have been determined as phenols, peptides, alkaloids or terpenoids (Falch, 1996). Screening of lipophilic and hydrophilic extracts from cultured cyanobacteria or waterbloom material, isolated from German lakes and the Baltic sea for antiviral, antibiotic, immunomodulating and enzyme inhibiting activity in different in vitro systems revealed strains with interesting effects.

Effect of gravity changes on the cyanobacterium Synechocystis sp. PCC 6803.

The impact of hypergravity and simulated weightlessness were studied to check whether cyanobacteria perceive changes of gravity as stress. Hypergravity generated by a low-speed centrifuge increased slightly the overall activity of dehydrogenases, but the increase was the same for 90 g and 180 g. The protein pattern did not show qualitative alterations during hypergravity treatment up to 180 g.

Uptake and use of the osmoprotective compounds trehalose, glucosylglycerol, and sucrose by the cyanobacterium Synechocystis sp. PCC6803.

Accumulation of exogenously supplied osmoprotective compounds was analyzed in the cyanobacterium Synechocystis sp. PCC6803, which synthesizes glucosylglycerol as the principal osmoprotective compound. Glucosylglycerol and trehalose were accumulated to high levels and protected cells of a mutant unable to synthesize glucosylglycerol against the deleterious effects of salt stress.

[Investigations of the immunomodulatory effect of cyanobacterial extracts].

Resulting from the knowledge that cyanobacteria (blue-green algae) are able to produce pharmacologically active substances the aqueous extracts from several cyanobacteria species and strains (Microcystis aeruginosa, Synechocystis aquatilis, Oscillatoria redekei, Anabaena flos-aque, Aphanizomenon flos-aquae, Oscillatoria rubescens, Oscillatoria tenuis) were tested for their immunomodulating activity. Extracts from Oscillatoria redekei 051, Oscillatoria tenuis 01 and Synechocystis aquatilis 428 caused an immunosuppression. They inhibited not only the incorporation of 3H-thymidine into mitogen stimulated lymphocytes but reduced also the number of plaque-forming cells of mice as shown by hemolysis-plaque-assay.