An Interspecies Signaling System Mediated by Fusaric Acid Has Parallel Effects on Antifungal Metabolite Production by Pseudomonas protegens Strain Pf-5 and Antibiosis of Fusarium spp

Pseudomonas protegens strain Pf-5 is a rhizosphere bacterium that suppresses soilborne plant diseases and produces at least seven different secondary metabolites with antifungal properties. We derived mutants of Pf-5 with single and multiple mutations in biosynthesis genes for seven antifungal metab...

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Published in:Applied and environmental microbiology 2016-03, Vol.82 (5), p.1372-1382
Main Authors: Quecine, Maria Carolina, Kidarsa, Teresa A, Goebel, Neal C, Shaffer, Brenda T, Henkels, Marcella D, Zabriskie, T Mark, Loper, Joyce E
Format: Article
Language:English
Subjects:
Antibiosis
Antifungal Agents - metabolism
Bacteria
Biosynthesis
Culture Media - chemistry
Fusaric Acid - metabolism
Fusarium - drug effects
Fusarium - growth & development
Fusarium - metabolism
Fusarium oxysporum
Fusarium verticillioides
Genes
Metabolic Networks and Pathways - drug effects
Metabolites
Microbial Interactions
Mutation
Plant Microbiology
Pseudomonas
Pseudomonas - drug effects
Pseudomonas - growth & development
Pseudomonas - metabolism
Signal Transduction
Transcription, Genetic
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Summary:Pseudomonas protegens strain Pf-5 is a rhizosphere bacterium that suppresses soilborne plant diseases and produces at least seven different secondary metabolites with antifungal properties. We derived mutants of Pf-5 with single and multiple mutations in biosynthesis genes for seven antifungal metabolites: 2,4-diacetylphoroglucinol (DAPG), pyrrolnitrin, pyoluteorin, hydrogen cyanide, rhizoxin, orfamide A, and toxoflavin. These mutants were tested for inhibition of the pathogens Fusarium verticillioides and Fusarium oxysporum f. sp. pisi. Rhizoxin, pyrrolnitrin, and DAPG were found to be primarily responsible for fungal antagonism by Pf-5. Previously, other workers showed that the mycotoxin fusaric acid, which is produced by many Fusarium species, including F. verticillioides, inhibited the production of DAPG by Pseudomonas spp. In this study, amendment of culture media with fusaric acid decreased DAPG production, increased pyoluteorin production, and had no consistent influence on pyrrolnitrin or orfamide A production by Pf-5. Fusaric acid also altered the transcription of biosynthetic genes, indicating that the mycotoxin influenced antibiotic production by Pf-5 at the transcriptional level. Addition of fusaric acid to the culture medium reduced antibiosis of F. verticillioides by Pf-5 and derivative strains that produce DAPG but had no effect on antibiosis by Pf-5 derivatives that suppressed F. verticillioides due to pyrrolnitrin or rhizoxin production. Our results demonstrated the importance of three compounds, rhizoxin, pyrrolnitrin, and DAPG, in suppression of Fusarium spp. by Pf-5 and confirmed that an interspecies signaling system mediated by fusaric acid had parallel effects on antifungal metabolite production and antibiosis by the bacterial biological control organism.
ISSN:0099-2240
1098-5336
DOI:10.1128/AEM.02574-15