Akira Shirata

Brassicanal C and two dioxindoles from cabbage

Abstract Brassicanal C, a new sulphur-containing phytoalexin, and two dioxindoles were isolated from cabbage inoculated with Pseudomonas cichorii. Brassicanal C was shown to possess a unique sulphinate structure on the basis of spectroscopic data and optical activity. One of the dioxindoles, dioxibrassinin, appears structurally to be a possible precursor to spirobrassinin.

Three sulphur-containing stress metabolites from Japanese radish☆

Abstract Three new brassinin related stress metabolites, named brassitin, N-methoxyspirobrassinol methyl ether and N-methoxyspirobrassinol, were isolated from the Japanese radish ‘Daikon’ (Raphanus sativus var. hortensis) after inoculation with Pseudomonas cichorii. Their structures have been established on the basis of spectroscopic data and chemical reactions. N-Methoxyspirobrassinol has an unusual hemi-aminal structure, and occurs as a mixture of diastereomers. The occurrence of N-methoxyspirobrassinol methyl ether and N-methoxyspirobrassinol suggests the involvement of oxidized intermediates in the biosynthesis from brassinin to spirobrassinin

Antifungal compounds from Dioscorea batatas inoculated with Pseudomonas cichorii

Abstract An induced and six preformed antifungal compounds were isolated from Chinese yam ( Dioscorea batatas ) inoculated with the bacterium Pseudomonas cichorii . The induced compound, a phytoalexin, was identified as dihydropinosylvin. The preformed compounds were characterized as oxygenated bibenzyls and phenanthrenes.

Structures of moracins E, F, G, and H, new phytoalexins from diseased mulberry

Abstract The structures and antifungal activity of four new mulberry phytoalexins, designated as moracins E, F, G, and H, are described.

Proposal of Mycetocola gen. nov. in the family Microbacteriaceae and three new species, Mycetocola saprophilus sp. nov., Mycetocola tolaasinivorans sp. nov. and Mycetocola lacteus sp. nov., isolated from cultivated mushroom, Pleurotus ostreatus.

The taxonomic positions of 10 tolaasin-detoxifying bacteria, which were isolated from the cultivated mushroom Pleurotus ostreatus, were investigated. These strains are Gram-positive, obligately aerobic, non-sporulating and irregular rod-shaped bacteria. They have the following characteristics: the major menaquinone is MK-10, the DNA G+C content ranges from 64 to 65 mol%, the diamino acid in the cell wall is lysine and the muramic acid in the peptidoglycan is an acetyl type. The major fatty acids are anteiso-C15:0 and anteiso-C17:0. On the basis of morphological, physiological and chemotaxonomic characteristics, together with DNA-DNA reassociation values and 16S rRNA gene sequence comparison data, the new genus Mycetocola gen. nov. is proposed for these bacteria in the family Microbacteriaceae and three new species are also proposed: Mycetocola saprophilus sp. nov. (type strain CM-01T = IFO 16274T = MAFF 211324T = NRRL B-24119T), Mycetocola tolaasinivorans sp. nov. (type strain CM-05T = IFO 16277T = MAFF 211325T = NRRL B-24120T) and Mycetocola lacteus sp. nov. (type strain CM-10T = IFO 16278T = MAFF 211326T = NRRL B-24121T). The type species of the genus is Mycetocola saprophilus sp. nov.

Identification of non-pseudomonad bacteria from fruit bodies of wild Agaricales fungi that detoxify tolaasin produced by Pseudomonas tolaasii

Bacterial isolates from wild Agaricales fungi detoxified tolaasin, the inducer of brown blotch disease of cultivated mushrooms produced by Pseudomonas tolaasii. Mycetocola tolaasinivorans and Mycetocola lacteus were associated with fruit bodies of wild Pleurotus ostreatus and wild Lepista nuda, respectively. Tolaasin-detoxifying bacteria belonging to other genera were found in various wild mushrooms. An Acinetobacter sp. was isolated from fruit bodies of Tricholoma matsutake, Bacillus pumilus was isolated from Coprinus disseminatus, and Sphingobacterium multivorum was isolated from Clitocybe clavipes. A Pedobacter sp., which seemed not be identifiable as any known bacterial species, was isolated from a Clitocybe sp. Tolaasin-detoxifying bacteria identified thus far were attached to the surface of mycelia rather than residing within the fungal cells. M. tolaasinivorans, M. lacteus, B. pumilus, the Pedobacter sp., and S. multivorum efficiently detoxified tolaasin and strongly suppressed brown blotch development in cultivated P. ostreatus and Agaricus bisporus in vitro, but the Acinetobacter sp. did so less efficiently. These bacteria may be useful for the elucidation of mechanisms involved in tolaasin-detoxification, and may become biological control agents of mushroom disease.

A guaianolide phytoalexin, cichoralexin, from Cichorium intybus.

Abstract A sesquiterpenoid phytoalexin, cichoralexin was isolated from Cichorium intybus inoculated with Pseudomonas cichorii . Its structure has been elucidated by spectroscopic methods.

Isolation of three novel sulphur-containing phytoalexins from the chinese cabbage Brassica campestris L. ssp. pekinensis(cruciferae)

Inoculation of Chinese cabbage heads with the bacterium Pseudomonas cichorii induced the production of three major phytoalexins named methoxybrassinin (1), brassinin (2), and cyclobrassinin (3), whose structures have been elucidated on the basis of spectroscopic studies and synthesis.

4-Methoxybrassinin, a sulphur-containing phytoalexin from Brassica oleracea☆

Abstract Inoculation of white cabbage heads with Pseudomonas cichorii resulted in induction of a new phytoalexin, 4-methoxybrassinin, whose structure was elucidated on the basis of spectroscopic methods. Five known cruciferous phytoalexins were also isolated.

rtpA, a gene encoding a bacterial two-component sensor kinase, determines pathogenic traits of Pseudomonas tolaasii, the causal agent of brown blotch disease of a cultivated mushroom, Pleurotus ostreatus

Pseudomonas tolaasii strain PT814 produces extracellular toxins, tolaasins, and a volatile toxin, tovsin, that are responsible for the induction of brown blotch and rotting, respectively, in a cultivated mushroom,Pleurotus ostreatus. Insertions of single transposon mini-Tn5Km 1 into the chromosome ofP. tolaasii strain PT814 generated mutants that are pleiotropically defective in tolaasin and protease production, and altered in colony morphology. The mutants, however, produce tovsin at the level of wild-type. Variants phenotypically similar to the pleiotropic mutants ofP. tolaasii strain PT814 spontaneously occurred inP. tolaasii strain S8501 at 22–30°C in vitro. The occurrence of variants was significantly reduced in the presence of extracts ofP ostreatus or at a temperature of 15–20°C. ThertpA gene (rtpA=regulator gene of tolaasin production and other pleiotropic traits) isolated from aP. tolaasii strain PT814 gene library restored the wild-type phenotype in both the mini-Tn5km 1 insertion and spontaneous mutants. mini-Tn5km 1 insertions were also located in the allele ofrtpA. Nucleotide sequencing of thertpA DNA revealed an open reading frame of 2,751 bp predicted to encode a protein consisting of 917 amino acid residues with a molecular mass of 100.6 kDa and displaying the conserved amino acid sequence of both sensor, and receiver domains of “bacterial two-component regulators”. The data suggest that the machinery responding to environmental stimuli is essential for the pathogenic interaction ofP. tolaasii with the mushroom.