Environmental Microbiology (2008) 10, 778-788

Maaike Perneel, Liesbet D'Hondt, Katrien De Maeyer, Amayana Adiobo, Korneel Rabaey and Monica Höfte (2008)
Phenazines and biosurfactants interact in the biological control of soil-borne diseases caused by Pythium spp.
Environmental Microbiology 10 (3), 778-788
Abstract: In this study, the putative role of phenazines and rhamnolipid-biosurfactants, antagonistic metabolites produced by Pseudomonas aeruginosa PNA1, was tested in the biological control of Pythium splendens on bean (Phaseolus vulgaris L) and Pythium myriotylum on cocoyam (Xanthosoma sagittifolium L Schott). A rhamnolipid-deficient and a phenazine-deficient mutant of PNA1 were used either separately or jointly in plant experiments. When the mutants were applied separately, no disease-suppressive effect was observed, although both mutants still produced one of the antagonistic compounds (phenazines or rhamnolipids). When the mutants were concurrently introduced in the soil, the biocontrol activity was restored to wild-type levels. Bean seeds developed significantly less pre-emergence damping-off caused by P. splendens when treated with a mixture of purified phenazine-1-carboxamide and rhamnolipids than with any of the chemicals alone. When phenazines and rhamnolipids were combined at concentrations that had no observable effects when the metabolites were applied separately, mycelial growth of P. myriotylum was significantly reduced. In addition, microscopic analysis revealed substantial vacuolization and disintegration of Pythium hyphae after incubation in liquid medium amended with both metabolites. Results of this study indicate that phenazines and biosurfactants are acting synergistically in the control of Pythium spp.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Monica Höfte

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pythium myriotylum	Cocoyam (Xanthosoma)
	Globisporangium splendens	Beans (Phaseolus)
Pseudomonas aeruginosa (antagonist)	Pythium myriotylum	Cocoyam (Xanthosoma)
Pseudomonas aeruginosa (antagonist)	Globisporangium splendens	Beans (Phaseolus)