Chitinous components of the cell wall of Fusarium oxysporum.

The cell wall of Fusarium oxysporum f. sp. lycopersici was digested with chitinase to analyze the structure of its chitinous components. In spite of a similar acetylation degree of the cell wall components to that of 25-35% acetylated chitosan, only N-acetylglucosamine disaccharide [(GlcNAc)2] was obtained from chitinase hydrolyzate of the fungal cell wall by CM-Sephadex C-25 column chromatography, while (GlcNAc)2 and several types of deacetylated chitooligosaccharides were separated from that of 25-35% acetylated chitosan. The results indicate that N-acetylglucosamine residues in the polysaccharide chains of the fungal cell wall are most likely condensed into some region, while acetylated residues are more scattered in 25-35% acetylated chitosan.     

Fusarium oxysporum homogenates and jasmonate induce limited sanguinarine accumulation in Argemone mexicana cell cultures

In vitro cultures of Argemone mexicana (Papaveraceae) were induced from leaves of mature plants. Sanguinarine, a benzophenanthridine, was the main alkaloid in the cultures, even in the absence of inducers of secondary metabolism. The accumulation of this metabolite was increased by adding methyl jasmonate and fungal elicitors, although in a limited fashion in comparison to other sanguinarine-producing species. Evidence of a transport mechanism, which may be related to the magnitude of the response, was obtained based on the fluorescent properties of bezophenathridines in the elicited cultures.     

Comparison of Fusarium oxysporum and Fusarium oxysporum var. redolens by Analyzing the Isozyme and Serological Patterns

Extracts from Fusarium oxysporum (F.o.) and F. oxysporum var. redolens (F.o.r.) isolates were compared by means of electrophoresis and crossed immunoelectrophoresis. The polymorphism of five isozyme systems allowed a distinction between F.o. and F.o.r. isolates. The isozyme patterns of three other isozyme systems did not allow this distinction between F.o. and F.o.r. to be made. Both fungi appeared almost identical serologically. Relative amounts of their corresponding proteins differed but the qualitative patterns of the proteins were nearly the same with the anti-F.o.r. serum, only one specific antigen was detected in the extracts from F.o.r., isolates. Although the results obtained indicate a strong similarity between F.o. and F.o.r., they are not sufficient for an unequivocal statement that the fungi belong to the same species.     

Phenolic removal of olive-mill dry residues by laccase activity of white-rot fungi and its impact on tomato plant growth

We studied the influence of the laccase activity of two white-rot fungi on the toxic effect of water-soluble substances from dry residues of olives (ADOR) on tomato plants. Pycnoporus cinnabarinus and Coriolopsis rigida decreased the phenol content of ADOR to 73% after 15 days. P. cinnabarinus and C. rigida produced laccase activity after 5 and 15 days, respectively, and the highest activity in both fungi was detected at 20 days. The treatment of ADOR with these white-rot fungi decreased the phytotoxicity of this residue on tomato plants. A close relationship was found between the amount of laccase produced, the decrease in phenol content of ADOR by the saprobic fungi, decrease of phytotoxicity of ADOR, and the increase in dry weight of tomato plants. These results show that phenol removal by the laccase activity of white-rot fungi can be important in the elimination of phytotoxic substances present in olive-mill dry residues.     

Purification and properties of nitroalkane oxidase from Fusarium oxysporum.

A nitroalkane-oxidizing enzyme, which was inducibly formed by addition of nitroethane to the medium was purified to homogeneity from an extract of Fusarium oxysporum (IFO 5942) with an overall yield of about 20%. The enzyme catalyzed the oxidative denitrification of 1-nitropropane as follows: CH2(NO2)CH2CH3 + O2 + H2O leads to OHCCH2CH3 + HNO2 + H2O2. In addition to 1-nitropropane, 3-nitro-2-pentanol, 2-nitropropane, and nitrocyclohexane are good substrates; the enzyme is designated "nitroalkane oxidase" (EC class 1.7.3). The enzyme has a molecular weight of approximately 185,000 and consists of four subunits identical in molecular weight (47,000). Flavin adenine dinucleotide was required for the enzyme activity and could be replaced in part by riboflavin 5'-phosphate. The maximum reactivity was found at about pH 8.0. The enzyme was inhibited significantly by HgCl2, KCN, p-chloromercuribenzoate, and N-ethylmaleimide. The Michaelis constants are as follows: 1-nitropropane, 1.54 mM; 2-nitropropane, 7.40 mM; nitroethane, 1.00 mM; 3-nitro-2-pentanol, 3.08 mM; nitrocyclohexane, 0.90 mM; and flavin adenine dinucleotide, 1.33 micrometer.     

Carbon and nitrogen requirements of Fusarium oxysporum causing cotton wilt

Summary The present work was carried out to study the nutritional requirements of the cotton wilt-inducing fungus, i.e.Fusarium oxysporum on a synthetic liquid medium with regard to the carbon and nitrogen sources at varying concentrations in terms of the average mycelial dry weights.The optimum carbon requirements of the fungus ranged from 7000–8000 p.p.m. irrespective of the carbon source used in experiment. Carbon utilization was best on sucrose followed by maltose, starch, glucose, fructose and cellulose successively.The optimum nitrogen requirements of the fungus were 300 p.p.m. of nitrogen in the medium; nitrogen utilization was best on using nitrate-nitrogen followed by glycine, glutamic acid, ammonium nitrate, asparagine and ammonium sulphate.Maximum growth of the fungus took place on media containing a C/N ratio ranging between 22.8 and 25.7.Colour formation is correlated with varying either source or concentration of nitrogen and not carbon.     

Purification and characterization of a novel lactonohydrolase, catalyzing the hydrolysis of aldonate lactones and aromatic lactones, from Fusarium oxysporum.

A novel lactonohydrolase, an enzyme that catalyzes the hydrolysis of aldonate lactones to the corresponding aldonic acids, was purified 10-fold to apparent homogeneity, with a 61% overall recovery, from Fusarium oxysporum AKU 3702, through a purification procedure comprising DEAE-Sephacel, octyl-Sepharose CL-4B and hydroxyapatite chromatographies and crystallization. The molecular mass of the native enzyme, as estimated by high-performance gel-permeation chromatography, is 125 kDa, and the subunit molecular mass is 60 kDa. The enzyme contains 15.4% (by mass) glucose equivalent of carbohydrate, and about 1 mol calcium/subunit. The enzyme hydrolyzes aldonate lactones, such as D-galactono-gamma-lactone and L-mannono-gamma-lactone, stereospecifically. Furthermore, it can catalyze the asymmetric hydrolysis of D-pantoyl lactone, which is a promising chiral building block for the chemical synthesis of D-pantothenate. These reactions are reversible, and the reaction equilibrium at pH 6.0 has a molar ratio of nearly 1:1 with D-pantoyl lactone and D-pantoic acid. The Km and Vmax for D-galactono-gamma-lactone are 3.6 mM and 1440 U/mg, respectively, and those for D-galactonate are 52.6 mM and 216 U/mg, respectively. The enzyme also irreversibly hydrolyzes several aromatic lactones, such as dihydrocoumarin and homogentisic-acid lactone.     

Production of Intraspecific Hybrids of Fusarium oxysporum f. sp. radicis-lycoperisici and Fusarium oxysporum f. sp. lycopersici by Protoplast Fusions

The fusion of protoplasts from the cycloheximide-resistant mutant FOL(C) of Fusarium oxysporum f. sp. lycopersici (FOL) and the mycostatin-resistant mutant FORL(M) of F. oxysporum f. sp. radicis-lycopersici (FORL), produced hybrids which expressed significant differences from the parents in their pathogenicity and growth and in the electrophoretic separation patterns of their proteins, enzymes and isoenzymes. The results suggest a transformed genetic basis for these altered expressions and the feasibility of using protoplast fusion technology for examining the biology of pathogenicity genes and for elucidating the disease and virulence potential for new races from within hybridisable taxa of Fusarium spp. Such information would be useful for the design and development of long-term control systems for Fusarium diseases, particularly in breeding programs for disease resistance in crops.     

Purification and Characterization of an Alkaliphilic Choline Oxidase of Fusarium oxysporum

Uptake of cesium, potassium, and rubidium by Rhodococcus erythropolis CS98 and Rhodococcus sp. strain CS402 followed Michaelis-Menten saturation kinetics. The K_m’s for uptake of these monovalent cations by R. erythropolis CS98 and Rhodococcus sp. strain CS402 were 136 and 436μM for Cs⁺, 65 and 101μM for K⁺, and 102 and 113μM for Rb⁺, respectively. These values were significantly lower than those of Rhodobacter capsulatus and the Kup system in Escherichia coli. Potassium was a competitive inhibitor of cesium uptake by these strains, suggesting that cesium was accumulated by the potassium transport system. Although an uncoupler, FCCP, inhibited the cesium transport system, this system was not repressed by high concentrations of potassium in both Rhodococcus strains. However, the specificity in both Rhodococcus strains was different from the Trk system. These results suggest that the potassium transport system which can transport cesium in both Rhodococcus strains may be novel.     

Differentiation of Fusarium oxysporum from Fusarium solani by growth and pigmentation on media containing sugar alcohols

The growth and pigmentation of 99 strains of Fusarium , mainly of Fusarium oxysporum and F. solani , on ammonium salts agar containing either mannitol, sorbitol or xylitol as sole source of carbon is described. After 7–14 d incubation strains of F. oxysporum could be distinguished from F. solani by both their pigmentation and the size and shape of conidiogenous cells. The application of these media to routine screening of isolates is discussed.     

Pathogenicity of Fusarium oxysporum to Easter lily, narcissus and gladiolus

Isolates of Fusarium oxysporum from roots, bulbs and stems of Easter lilies (Lilium longiflorum) differed widely in pathogenicity and also, apparently, in tissue specificity. Virulent isolates caused a typical basal rot and root rot (but not a wilt) in which the mycelium advanced intercellularly through the scales and basal plates. Mildly pathogenic isolates became established in mature or senescent outer scales, at first producing only superficial effects, but further growth of mycelium occurred as the outer scales died and sometimes continued until the dead tissues were permeated and chlamydospores were formed. The underlying scales were then colonized. The modes of pathogenicity and survival in Easter lily were compared with those of the F. oxysporum formae causing bulb rots of gladiolus and narcissus. It is suggested that advance of hyphae by penetration between the cells of the vascular parenchyma, which is common in isolates causing rots in bulbs and corms, represents a stage in the evolution of the truly vascular habit among fusaria.     

A structured kinetic model for suspension cultures of Taxus chinensis var. mairei induced by an oligosaccharide from Fusarium oxysporum

A structured kinetic model was established to describe the process of Taxol formation in suspension cultures of Taxus chinesis var. mairei induced by an oligosaccharide from Fusarium oxysporum. In this model, the role of intracellular starch as a storage carbon source had to be taken into account. Substrate uptake, culture growth, cell respiration, and secondary metabolites, predicted by the model, agreed with those obtained experimentally. The effective factors of oligosaccharide elicitation, _e,j, defined as the ratio of the parameter values in the system with oligosaccharide to those in control, reflected the effects of the oligosaccharide on cell growth and Taxol production.     

Species-specific primers for Fusarium redolens and a PCR-RFLP technique to distinguish among three clades of Fusarium oxysporum

The currently available morphological and molecular diagnostic techniques for Fusarium redolens and the three phylogenetic clades of Fusarium oxysporum are problematic. Aligned translation elongation factor 1 alpha (TEF-1 alpha) gene sequences from these species and their close relatives were used to design F. redolens-specific primers, and to identify restriction sites that discriminate among the three clades of F. oxysporum. The F. redolens-specific primers distinguished this species from all others included in the study. There were three TEF-1 alpha-RFLP patterns among formae speciales of F. oxysporum. These PCR-RFLP patterns corresponded with the three clades. These techniques provide simple and inexpensive diagnostic methods for the identification of F. redolens and members of the three clades of F. oxysporum.