Abstract
There is increasing evidence that communication between members of the same species, as well as members of different species, is important for the survival of microorganisms in diverse ecological niches, such as the rhizosphere. To investigate whether the phytopathogen Pythium ultimum could alter gene expression in the biocontrol strain Pseudomonas fluorescens F113, which protects the roots of sugar beet from the fungus, a screening system was developed to detect differential expression of bacterial genes in the presence of P. ultimum. The transposon Tn5, containing a promoterless lacZ reporter gene, was used to generate a library of transcriptional gene fusions in P. fluorescens F113. By this screening procedure, five P. fluorescens F113 gene clusters were identified and shown to be repressed in the presence of P. ultimum. The ecological fitness of three of the five reporter mutants in the rhizosphere of seed-inoculated sugar beet was lower than that of the wild type. Furthermore, all five mutants were impaired in their ability to subsequently colonize the rhizosphere of uninoculated sugar beet sown repeatedly in the same soil. With the exception of reporter mutant SF10, which was impaired in nitrogen metabolism, the reporter mutants had growth requirements and biocontrol abilities similar to those of the wild type. This is the first reported case of a fungus repressing the expressing of bacterial genes.
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- Birnboim H. C., Doly J. A rapid alkaline extraction procedure for screening recombinant plasmid DNA. Nucleic Acids Res. 1979 Nov 24;7(6):1513–1523. doi: 10.1093/nar/7.6.1513. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Boyer H. W., Roulland-Dussoix D. A complementation analysis of the restriction and modification of DNA in Escherichia coli. J Mol Biol. 1969 May 14;41(3):459–472. doi: 10.1016/0022-2836(69)90288-5. [DOI] [PubMed] [Google Scholar]
- Brazil G. M., Kenefick L., Callanan M., Haro A., de Lorenzo V., Dowling D. N., O'Gara F. Construction of a rhizosphere pseudomonad with potential to degrade polychlorinated biphenyls and detection of bph gene expression in the rhizosphere. Appl Environ Microbiol. 1995 May;61(5):1946–1952. doi: 10.1128/aem.61.5.1946-1952.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Carroll H., Moenne-Loccoz Y., Dowling D. N., O'gara F. Mutational Disruption of the Biosynthesis Genes Coding for the Antifungal Metabolite 2,4-Diacetylphloroglucinol Does Not Influence the Ecological Fitness of Pseudomonas fluorescens F113 in the Rhizosphere of Sugarbeets. Appl Environ Microbiol. 1995 Aug;61(8):3002–3007. doi: 10.1128/aem.61.8.3002-3007.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Castric K. F., Castric P. A. Method for rapid detection of cyanogenic bacteria. Appl Environ Microbiol. 1983 Feb;45(2):701–702. doi: 10.1128/aem.45.2.701-702.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chen W. P., Kuo T. T. A simple and rapid method for the preparation of gram-negative bacterial genomic DNA. Nucleic Acids Res. 1993 May 11;21(9):2260–2260. doi: 10.1093/nar/21.9.2260. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fenton A. M., Stephens P. M., Crowley J., O'Callaghan M., O'Gara F. Exploitation of gene(s) involved in 2,4-diacetylphloroglucinol biosynthesis to confer a new biocontrol capability to a Pseudomonas strain. Appl Environ Microbiol. 1992 Dec;58(12):3873–3878. doi: 10.1128/aem.58.12.3873-3878.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Finan T. M., Kunkel B., De Vos G. F., Signer E. R. Second symbiotic megaplasmid in Rhizobium meliloti carrying exopolysaccharide and thiamine synthesis genes. J Bacteriol. 1986 Jul;167(1):66–72. doi: 10.1128/jb.167.1.66-72.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fischer H. M. Genetic regulation of nitrogen fixation in rhizobia. Microbiol Rev. 1994 Sep;58(3):352–386. doi: 10.1128/mr.58.3.352-386.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Herrero M., de Lorenzo V., Timmis K. N. Transposon vectors containing non-antibiotic resistance selection markers for cloning and stable chromosomal insertion of foreign genes in gram-negative bacteria. J Bacteriol. 1990 Nov;172(11):6557–6567. doi: 10.1128/jb.172.11.6557-6567.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mazzola M., Cook R. J. Effects of fungal root pathogens on the population dynamics of biocontrol strains of fluorescent pseudomonads in the wheat rhizosphere. Appl Environ Microbiol. 1991 Aug;57(8):2171–2178. doi: 10.1128/aem.57.8.2171-2178.1991. [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]
- de Lorenzo V., Herrero M., Jakubzik U., Timmis K. N. Mini-Tn5 transposon derivatives for insertion mutagenesis, promoter probing, and chromosomal insertion of cloned DNA in gram-negative eubacteria. J Bacteriol. 1990 Nov;172(11):6568–6572. doi: 10.1128/jb.172.11.6568-6572.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]