scholarly journals Defense Responses of Fusarium oxysporum to 2,4-Diacetylphloroglucinol, a Broad-Spectrum Antibiotic Produced by Pseudomonas fluorescens

2004 ◽  
Vol 17 (11) ◽  
pp. 1201-1211 ◽  
Author(s):  
Alexander Schouten ◽  
Grardy van den Berg ◽  
Véronique Edel-Hermann ◽  
Christian Steinberg ◽  
Nadine Gautheron ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Pseudomonas Fluorescens ◽  
Broad Spectrum ◽  
Acid Production ◽  
Fusaric Acid ◽  
Geographic Origin ◽  
Intergenic Spacer ◽  
Pathogenic Fungi ◽  
Defense Responses ◽  
Broad Spectrum Antibiotic

A collection of 76 plant-pathogenic and 41 saprophytic Fusarium oxysporum strains was screened for sensitivity to 2,4-diacetylphloroglucinol (2,4-DAPG), a broad-spectrum antibiotic produced by multiple strains of antagonistic Pseudomonas fluorescens. Approximately 17% of the F. oxysporum strains were relatively tolerant to high 2,4-DAPG concentrations. Tolerance to 2,4-DAPG did not correlate with the geographic origin of the strains, formae speciales, intergenic spacer (IGS) group, or fusaric acid production levels. Biochemical analysis showed that 18 of 20 tolerant F. oxysporum strains were capable of metabolizing 2,4-DAPG. For two tolerant strains, analysis by mass spectrometry indicated that deacetylation of 2,4-DAPG to the less fungitoxic derivatives monoacetylphloroglucinol and phloroglucinol is among the initial mechanisms of 2,4-DAPG degradation. Production of fusaric acid, a known inhibitor of 2,4-DAPG biosynthesis in P. fluorescens, differed considerably among both 2,4-DAPG-sensitive and -tolerant F. oxysporum strains, indicating that fusaric acid production may be as important for 2,4-DAPG-sensitive as for -tolerant F. oxysporum strains. Whether 2,4-DAPG triggers fusaric acid production was studied for six F. oxysporum strains; 2,4-DAPG had no significant effect on fusaric acid production in four strains. In two strains, however, sublethal concentrations of 2,4-DAPG either enhanced or significantly decreased fusaric acid production. The implications of 2,4-DAPG degradation, the distribution of this trait within F. oxysporum and other plant-pathogenic fungi, and the consequences for the efficacy of biological control are discussed.

scholarly journals The use of Bacillus subtilis for screening fusaric acid production by Fusarium spp.

2009 ◽  
Vol 27 (No. 3) ◽  
pp. 203-209 ◽  
Author(s):  
A. Šrobárová ◽  
Š. Eged ◽  
J. Teixeira Da Silva ◽  
A. Ritieni ◽  
A. Santini
Keyword(s):  
Bacillus Subtilis ◽  
Secondary Metabolites ◽  
Thin Layer ◽  
Fusarium Oxysporum ◽  
Thin Layer Chromatography ◽  
Screening Test ◽  
Acid Production ◽  
Fusaric Acid ◽  
Modified Method ◽  
Layer Chromatography

Fusaric acid (FA) is one of the most important secondary metabolites produced by <I>Fusarium oxysporum</I> (Schlecht) (FO), <I>F. solani</I> (Mart.) Appel & Wollenweber, and <I>F. moniliforme</I> Sheldon. It is toxic to humans, many plants, and microorganisms and it enhances the toxicity of fumonisin and trichothecene. A simple and rapid method for fusaric acid (FA) screening in <I>Fusarium</I> isolates was developed. In this study, several strains of <I>Fusarium oxysporum</I> were tested for their ability to produce FA by using a suitable race of <I>Bacillus subtilis</I> as the bioassay. A modified method using small agar blocks with the fungus producing FA was applied in the screening test. FA standard and <I>F. culmorum</I> were used as controls. The experimental <I>F. oxysporum</I> isolates and FA standard produced transparent zones on the plates with <I>Bacillus subtilis</I>. The differences in size of the transparent zones corresponded to the quantity of FA when thin-layer chromatography was used.

scholarly journals Evaluation of Nonpathogenic Fusarium oxysporum and Pseudomonas fluorescens for Panama Disease Control

Plant Disease ◽  
2011 ◽  
Vol 95 (8) ◽  
pp. 951-959 ◽  
Author(s):  
A. Belgrove ◽  
C. Steinberg ◽  
A. Viljoen
Keyword(s):  
Fusarium Oxysporum ◽  
Pseudomonas Fluorescens ◽  
Fusarium Wilt ◽  
Intergenic Spacer ◽  
Polymorphism Analysis ◽  
Panama Disease ◽  
Intergenic Spacer Region ◽  
Soil Microbial ◽  
Fusarium Wilt Of Banana ◽  
Species Specific

Nonpathogenic Fusarium oxysporum endophytes from healthy banana roots were evaluated for their ability to reduce Fusarium wilt of banana (Panama disease). Isolates were identified morphologically and by using species-specific primers. Pathogenicity was confirmed by inoculating banana plantlets in the greenhouse. Nonpathogenic F. oxysporum isolates were grouped into 14 haplotype groups by polymerase chain reaction restriction fragment length polymorphism analysis of the intergenic spacer region, and representative isolates evaluated for biocontrol of F. oxysporum f. sp. cubense. In the greenhouse, 10 nonpathogenic F. oxysporum isolates were able to significantly reduce Fusarium wilt of banana. The isolate that protected banana plantlets best in the greenhouse, a nonpathogenic F. oxysporum from the root rhizosphere, and Pseudomonas fluorescens WCS 417 were then field tested. When the putative biological control organisms were tested in the field, neither the nonpathogenic F. oxysporum, P. fluorescens, nor combinations thereof reduced Fusarium wilt development significantly. A number of factors could contribute to the lack of field protection, including soil microbial and chemical composition and reduced survival of biocontrol organisms in banana roots. A lack of knowledge regarding the etiology of Fusarium wilt of ‘Cavendish’ banana in the subtropics and the effect of F. oxysporum f. sp. cubense race and banana cultivar in protection of banana by biocontrol organisms should be further investigated.

scholarly journals Genetic Diversity and Population Structure of Races of Fusarium oxysporum Causing Cotton Wilt

2020 ◽  
Vol 10 (9) ◽  
pp. 3261-3269
Author(s):  
Hannah C Halpern ◽  
Peng Qi ◽  
Robert C Kemerait ◽  
Marin T Brewer
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Fusarium Oxysporum ◽  
Principal Components ◽  
Phylogenetic Trees ◽  
Elongation Factor ◽  
Intergenic Spacer ◽  
Pathogenic Fungi ◽  
The United States ◽  
Intergenic Spacer Region

Abstract To better understand the evolution of virulence we are interested in identifying the genetic basis of this trait in pathogenic fungi and in developing tools for the rapid characterization of variation in virulence among populations associated with epidemics. Fusarium oxysporum f. sp. vasinfectum (FOV) is a haploid fungus that causes devastating outbreaks of Fusarium wilt of cotton wherever it is grown. In the United States, six nominal races and eleven genotypes of FOV have been characterized based on the translation elongation factor (EF-1α) gene and intergenic spacer region (IGS), but it is unclear how race or genotype based on these regions relates to population structure or virulence. We used genotyping-by-sequencing to identify SNPs and determine genetic diversity and population structure among 86 diverse FOV isolates. Six individuals of Fusarium oxysporum closely related to FOV were genotyped and included in some analyses. Between 193 and 354 SNPs were identified and included in the analyses depending on the pipeline and filtering criteria used. Phylogenetic trees, minimum spanning networks (MSNs), principal components analysis (PCA), and discriminant analysis of principal components (DAPC) demonstrated that races and genotypes of FOV are generally not structured by EF-1α genotype, nor are they monophyletic groups with the exception of race 4 isolates, which are distinct. Furthermore, DAPC identified between 11 and 14 genetically distinct clusters of FOV, whereas only eight EF-1α genotypes were represented among isolates; suggesting that FOV, especially isolates within the widely distributed and common race 1 genotype, is more genetically diverse than currently recognized.

scholarly journals Fusaric Acid Production in Fusarium oxysporum Transformants Generated by Restriction Enzyme-Mediated Integration Procedure

2013 ◽  
Vol 19 (4) ◽  
pp. 254-258 ◽  
Author(s):  
Theresa Lee ◽  
Jean Young Shin ◽  
Seung Wan Son ◽  
Soohyung Lee ◽  
Jae-Gee Ryu
Keyword(s):  
Fusarium Oxysporum ◽  
Restriction Enzyme ◽  
Acid Production ◽  
Fusaric Acid ◽  
Integration Procedure

scholarly journals EM5519,a new broad-spectrum antibiotic produced by Pseudomonas fluorescens.

1983 ◽  
Vol 36 (2) ◽  
pp. 190-193 ◽  
Author(s):  
EDWARD MEYERS ◽  
RAYMOND COOPER ◽  
WILLIAM H. TREJO ◽  
NAFSIKA GEORGOPAPADAKOU ◽  
RICHARD B. SYKES
Keyword(s):  
Pseudomonas Fluorescens ◽  
Broad Spectrum ◽  
Broad Spectrum Antibiotic

scholarly journals Zinc Improves Biocontrol of Fusarium Crown and Root Rot of Tomato by Pseudomonas fluorescens and Represses the Production of Pathogen Metabolites Inhibitory to Bacterial Antibiotic Biosynthesis

1997 ◽  
Vol 87 (12) ◽  
pp. 1250-1257 ◽  
Author(s):  
Brion K. Duffy ◽  
Geneviève Défago
Keyword(s):  
Pseudomonas Fluorescens ◽  
Root Rot ◽  
Acid Production ◽  
Biocontrol Agent ◽  
Fusaric Acid ◽  
Antibiotic Biosynthesis ◽  
Production Of Hydrogen ◽  
Biocontrol Activity ◽  
Crown And Root Rot

Crown and root rot of tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici is an increasing problem in Europe, Israel, Japan, and North America. The biocontrol agent Pseudomonas fluorescens strain CHA0 provides only moderate control of this disease. A one-time amendment of zinc EDTA at 33 μg of Zn2+/ml to hydroponic nutrient solution in soilless rockwool culture did not reduce disease when used alone, but did reduce disease by 25% in the presence of CHA0. In in vitro studies with the pathogen, zinc at concentrations as low as 10 μg/ml abolished production of the phytotoxin fusaric acid, a Fusarium pathogenicity factor, and increased production of microconidia over 100-fold, but reduced total biomass. Copper EDTA at 33 μg of Cu2+/ml had a similar effect as zinc on the pathogen in vitro; it reduced disease when used alone, and increased the biocontrol activity of CHA0 in soilless culture. Ammonium-molybdate neither improved the biocontrol activity of CHA0 nor affected production of fusaric acid or microconidia. Strain CHA0 did not degrade fusaric acid. Fusaric acid at concentrations as low as 0.12 μg/ml repressed production by CHA0 of the antibiotic 2,4-diacetylphloroglucinol, a key factor in the biocontrol activity of this strain. Production of pyoluteorin by CHA0 was also reduced, but production of hydrogen cyanide and protease was not affected, suggesting that fusaric acid affects biosynthesis at a regulatory level downstream of gacA and apdA genes. Fusaric acid did not affect the recovery of preformed antibiotics nor did it affect bacterial growth even at concentrations as high as 200 μg/ml. When microbial meta-bolite production was measured in the rockwool bioassay, zinc amendments reduced fusaric acid production and enhanced 2,4-diacetylphloro-glucinol production. We suggest that zinc, which did not alleviate the repression of antibiotic biosynthesis by fusaric acid, improved biocontrol activity by reducing fusaric acid production by the pathogen, which resulted in increased antibiotic production by the biocontrol agent. This demonstrates that pathogens can have a direct negative impact on the mechanism(s) of biocontrol agents.

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