Cyclosporine A from a nonpathogenic Fusarium oxysporum suppressing Sclerotinia sclerotiorum.
OBJECTIVE
To evaluate the antagonistic activity of Fusarium oxysporum nonpathogenic fungal strain S6 against the phytopathogenic fungus Sclerotinia sclerotiorum and to identify the antifungal compounds involved.


RESULTS
The antagonistic activity of Fusarium oxysporum strain S6 was determined in vitro by dual cultures. The metabolite responsible for the activity was isolated by chromatographic techniques, purified and identified by spectroscopic methods as cyclosporine A. The antifungal activity against the pathogen was correlated with the presence of this metabolite by a dilution assay and then quantified. Cyclosporine A caused both growth inhibition and suppression of sclerotia formation. In a greenhouse assay, a significant increase in the number of surviving soybean (Glycine max) plants was observed when S. sclerotiorum and F. oxysporum (S6) were inoculated together when compared with plants inoculated with S. sclerotiorum alone.


CONCLUSIONS
Fusarium oxysporum (S6) may be a good fungal biological control agent for S. sclerotiorum and cyclosporine A is the responsible metabolite involved in its antagonistic activity in vitro.


CONCLUSIONS
Cyclosporine A has not been previously described as an inhibitor of S. sclerotiorum. Its minimum inhibitory concentration (MIC) of 0.1 microg disc(-1) makes it suitable to use as a biofungicide. In vivo experiments showed that F. oxysporum (S6) is a good candidate for the biocontrol of S. sclerotiorum in soybean.
Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428 EGA Buenos Aires, Argentina. arodrig@bg.fcen.uba.ar
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MA
Rodríguez
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Cabrera
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Godeas
D000935:Antifungal Agents / Q000032:analysis* / Q000494:pharmacology; D001203:Ascomycota / Q000187:drug effects* / Q000254:growth & development; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media; D016572:Cyclosporine / Q000032:analysis* / Q000494:pharmacology; D005516:Food Microbiology; D005670:Fusarium / Q000737:chemistry*; D008826:Microbial Sensitivity Tests / Q000379:methods; D010572:Pest Control, Biological / Q000379:methods; D012988:Soil Microbiology; D013025:Glycine max / Q000187:drug effects
D000935:Antifungal Agents; D003470:Culture Media; D016572:Cyclosporine