Phenazine antibiotics produced by fluorescent pseudomonads contribute to natural soil suppressiveness to Fusarium wilt

• Published in: The ISME Journal Vol. 3; no. 8; pp. 977 - 991
• Main Authors: Mazurier, Sylvie, Corberand, Thérèse, Lemanceau, Philippe, Raaijmakers, Jos M
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.08.2009; Nature Publishing Group
• Subjects: 2,4-diacetylphloroglucinol-producing pseudomonas; Antibiosis; Antibiotics; Antifungal Agents - metabolism; Antifungal Agents - pharmacology; Biodiversity; biological-control; Biomedical and Life Sciences; black root-rot; Carbon; chlororaphis pcl1391; Cluster Analysis; Colony Count, Microbial; Competition; DNA, Bacterial - genetics; dose-response relationships; Ecology; Evolutionary Biology; Flax - microbiology; Fusarium - drug effects; Fusarium - growth & development; Fusarium oxysporum; genetic diversity; Genotype; Genotypes; genotypic diversity; graminis var tritici; Life Sciences; Lycopersicon esculentum - microbiology; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Microbiology and Parasitology; Microorganisms; nonpathogenic fusarium; original-article; oxysporum fo47; Pathogens; Phenazines - metabolism; Phenazines - pharmacology; Phloroglucinol - analogs & derivatives; Phloroglucinol - metabolism; Phloroglucinol - pharmacology; Phylogeny; Plant Roots - microbiology; Polymorphism, Restriction Fragment Length; Pseudomonas; Pseudomonas - classification; Pseudomonas - metabolism; Pseudomonas - physiology; Soil Microbiology; Soils; disease-suppressive soil; fluorescent pseudomonads; Fusarium wilt; phenazine antibiotics; FUSARIUM WILT; PHENAZINE ANTIBIOTICS; FLUORESCENT PSEUDOMONADS; DISEASE SUPRESSIVE SOIL
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/ismej.2009.33

Natural disease-suppressive soils provide an untapped resource for the discovery of novel beneficial microorganisms and traits. For most suppressive soils, however, the consortia of microorganisms and mechanisms involved in pathogen control are unknown. To date, soil suppressiveness to Fusarium wilt disease has been ascribed to carbon and iron competition between pathogenic Fusarium oxysporum and resident non-pathogenic F. oxysporum and fluorescent pseudomonads. In this study, the role of bacterial antibiosis in Fusarium wilt suppressiveness was assessed by comparing the densities, diversity and activity of fluorescent Pseudomonas species producing 2,4-diacetylphloroglucinol (DAPG) ( phl D + ) or phenazine ( phz C + ) antibiotics. The frequencies of phl D + populations were similar in the suppressive and conducive soils but their genotypic diversity differed significantly. However, phl D genotypes from the two soils were equally effective in suppressing Fusarium wilt, either alone or in combination with non-pathogenic F. oxysporum strain Fo47. A mutant deficient in DAPG production provided a similar level of control as its parental strain, suggesting that this antibiotic does not play a major role. In contrast, phz C + pseudomonads were only detected in the suppressive soil. Representative phz C + isolates of five distinct genotypes did not suppress Fusarium wilt on their own, but acted synergistically in combination with strain Fo47. This increased level of disease suppression was ascribed to phenazine production as the phenazine-deficient mutant was not effective. These results suggest, for the first time, that redox-active phenazines produced by fluorescent pseudomonads contribute to the natural soil suppressiveness to Fusarium wilt disease and may act in synergy with carbon competition by resident non-pathogenic F. oxysporum .