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Degradation of pathogen quorum-sensing molecules by soil bacteria: a preventive and curative biological control mechanism
The plasmid pME6863, carrying the aiiA gene from the soil bacterium Bacillus sp. A24 that encodes a lactonase enzyme able to degrade N-acyl-homoserine lactones (AHLs), was introduced into the rhizosphere isolate Pseudomonas fluorescens P3. This strain is not an effective biological control agent aga...
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Published in: | FEMS microbiology ecology 2003-07, Vol.45 (1), p.71-81 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The plasmid pME6863, carrying the
aiiA gene from the soil bacterium
Bacillus sp. A24 that encodes a lactonase enzyme able to degrade
N-acyl-homoserine lactones (AHLs), was introduced into the rhizosphere isolate
Pseudomonas fluorescens P3. This strain is not an effective biological control agent against plant pathogens. The transformant
P. fluorescens P3/pME6863 acquired the ability to degrade AHLs. In planta,
P. fluorescens P3/pME6863 significantly reduced potato soft rot caused by
Erwinia carotovora and crown gall of tomato caused by
Agrobacterium tumefaciens to a similar level as
Bacillus sp. A24. Little or no disease reduction was observed for the wild-type strain P3 carrying the vector plasmid without
aiiA. Suppression of potato soft rot was observed even when the AHL-degrading
P. fluorescens P3/pME6863 was applied to tubers 2 days after the pathogen, indicating that biocontrol was not only preventive but also curative. When antagonists were applied individually with the bacterial plant pathogens, biocontrol activity of the AHL degraders was greater than that observed with several
Pseudomonas 2,4-diacetylphloroglucinol-producing strains and with
Pseudomonas chlororaphis PCL1391, which relies on production of phenazine antibiotic for disease suppression. Phenazine production by this well characterized biological control strain
P. chlororaphis PCL1391 is regulated by AHL-mediated quorum sensing. When
P. chlororaphis PCL1391 was co-inoculated with
P. fluorescens P3/pME6863 in a strain mixture, the AHL degrader interfered with the normally excellent ability of the antibiotic producer to suppress tomato vascular wilt caused by
Fusarium oxysporum f. sp.
lycopersici. Our results demonstrate AHL degradation as a novel biocontrol mechanism, but also demonstrate the potential for non-target interactions that can interfere with the biocontrol efficacy of other strains. |
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ISSN: | 0168-6496 1574-6941 |
DOI: | 10.1016/S0168-6496(03)00125-9 |