Abstract
The ability of Pseudomonas fluorescens F113 to produce the antibiotic 2,4-diacetylphloroglucinol (DAPG) is a key factor in the biocontrol of the phytopathogenic fungus Pythium ultimum by this strain. In this study, a DAPG-producing strain (rifampin-resistant mutant F113Rif) was compared with a nearly isogenic DAPG-negative biosynthesis mutant (Tn5::lacZY derivative F113G22) in terms of the ability to colonize and persist in the rhizosphere of sugarbeets in soil microcosms during 10 plant growth-harvest cycles totaling 270 days. Both strains persisted similarly in the rhizosphere for 27 days, regardless of whether they had been inoculated singly onto seeds or coinoculated in a 1:1 ratio. In order to simulate harvest and resowing, the roots were removed from the soil and the pots were resown with uninoculated sugarbeet seeds for nine successive 27-day growth-harvest cycles. Strains F113Rif and F113G22 performed similarly with respect to colonizing the rhizosphere of sugarbeet, even after nine cycles without reinoculation. The introduced strains had a transient effect on the size of the total culturable aerobic bacterial population. The results indicate that under these experimental conditions, the inability to produce DAPG did not reduce the ecological fitness of strain F113 in the rhizosphere of sugarbeets.
Full Text
The Full Text of this article is available as a PDF (270.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- De Weger L. A., van der Vlugt C. I., Wijfjes A. H., Bakker P. A., Schippers B., Lugtenberg B. Flagella of a plant-growth-stimulating Pseudomonas fluorescens strain are required for colonization of potato roots. J Bacteriol. 1987 Jun;169(6):2769–2773. doi: 10.1128/jb.169.6.2769-2773.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Loper J. E., Haack C., Schroth M. N. Population Dynamics of Soil Pseudomonads in the Rhizosphere of Potato (Solanum tuberosum L.). Appl Environ Microbiol. 1985 Feb;49(2):416–422. doi: 10.1128/aem.49.2.416-422.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mazzola M., Cook R. J., Thomashow L. S., Weller D. M., Pierson L. S., 3rd Contribution of phenazine antibiotic biosynthesis to the ecological competence of fluorescent pseudomonads in soil habitats. Appl Environ Microbiol. 1992 Aug;58(8):2616–2624. doi: 10.1128/aem.58.8.2616-2624.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shanahan P., O'sullivan D. J., Simpson P., Glennon J. D., O'gara F. Isolation of 2,4-diacetylphloroglucinol from a fluorescent pseudomonad and investigation of physiological parameters influencing its production. Appl Environ Microbiol. 1992 Jan;58(1):353–358. doi: 10.1128/aem.58.1.353-358.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thomashow L. S., Weller D. M., Bonsall R. F., Pierson L. S. Production of the antibiotic phenazine-1-carboxylic Acid by fluorescent pseudomonas species in the rhizosphere of wheat. Appl Environ Microbiol. 1990 Apr;56(4):908–912. doi: 10.1128/aem.56.4.908-912.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thomashow L. S., Weller D. M. Role of a phenazine antibiotic from Pseudomonas fluorescens in biological control of Gaeumannomyces graminis var. tritici. J Bacteriol. 1988 Aug;170(8):3499–3508. doi: 10.1128/jb.170.8.3499-3508.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wang Y. P., Birkenhead K., Boesten B., Manian S., O'Gara F. Genetic analysis and regulation of the Rhizobium meliloti genes controlling C4-dicarboxylic acid transport. Gene. 1989 Dec 21;85(1):135–144. doi: 10.1016/0378-1119(89)90473-3. [DOI] [PubMed] [Google Scholar]
- Weller D. M. Distribution of a Take-All Suppressive Strain of Pseudomonas fluorescens on Seminal Roots of Winter Wheat. Appl Environ Microbiol. 1984 Oct;48(4):897–899. doi: 10.1128/aem.48.4.897-899.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- van Peer Ron, Punte Helma L. M., de Weger Letty A., Schippers Bob. Characterization of Root Surface and Endorhizosphere Pseudomonads in Relation to Their Colonization of Roots. Appl Environ Microbiol. 1990 Aug;56(8):2462–2470. doi: 10.1128/aem.56.8.2462-2470.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]