Identification and Characterization of Bacteria-Derived Antibiotics for the Biological Control of Pea Aphanomyces Root Rot.

Antibiosis has been proposed to contribute to the beneficial bacteria-mediated biocontrol against pea Aphanomyces root rot caused by the oomycete pathogen . However, the antibiotics required for disease suppression remain unknown. In this study, we found that the wild type strains of Pf-5 and 2P24, but not their mutants that lack 2,4-diacetylphloroglucinol, strongly inhibited on culture plates. Purified 2,4-diacetylphloroglucinol compound caused extensive hyphal branching and stunted hyphal growth of . Using a GFP-based transcriptional reporter assay, we found that expression of the 2,4-diacetylphloroglucinol biosynthesis gene is activated by germinating pea seeds. The 2,4-diacetylphloroglucinol producing Pf-5 derivative, but not its 2,4-diacetylphloroglucinol non-producing mutant, reduced disease severity caused by on pea plants in greenhouse conditions. This is the first report that 2,4-diacetylphloroglucinol produced by strains of species plays an important role in the biocontrol of pea Aphanomyces root rot.