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Suppression of Root Diseases by Pseudomonas fluorescens CHA0: Importance of the Bacterial Secondary Metabolite 2,4-Diacetylphloroglucinol

1992; American Phytopathological Society; Volume: 5; Issue: 1 Linguagem: Inglês

10.1094/mpmi-5-004

1943-7706

Christoph Keel,

Plant Pathogens and Fungal Diseases

Pseudomonas fluorescens strain CHAO suppressesThielaviopsis basicola-induced black root rot of tobacco and Gaeumannomyces graminis var.tritici-induced take-all of wheat.Strain CHAO produces 2,4-diacetylphloroglucinol, a metabolite with antifungal, antibacterial, and phytotoxic activity.The role of this compound in disease suppression was tested under gnotobiotic conditions.A P. fluorescens mutant, obtained by Tn5 insertion, did not produce 2,4-diacetylphloroglucinol, showed diminished inhibition of T. basicola and of G. g. var.tritici in vitro, and had a reduced suppressive effect on tobacco black root rot and on take-all of wheat, compared with wild-type CHAO.Complementation of the mutant with an 11-kb DNA fragment from a genomic library of wild-type CHAO largely restored production of the metabolite, inhibition of the fungal pathogens in vitro and disease suppression.The Tn5 insertion was physically mapped using a 5.8-kb complementing fragment as a probe.2,4-Diacetylphloroglucinol was shown to be produced in the rhizosphere of wheat by strain CHAO and by the complemented mutant, but not by the mutant defective in 2,4-diacetylphloroglucinol synthesis.These results support the importance of 2,4-diacetylphloroglucinol production by strain CHAO in the suppression of soilborne plant pathogens in the rhizosphere.