The Role of 2,4-Diacetylphloroglucinol- and Phenazine-1-Carboxylic Acid-Producing Pseudomonas spp. in Natural Protection of Wheat from Soilborne Pathogens

Fluorescent Pseudomonas isolated from the rhizosphere of diverse plants have been studied as biocontrol agents of soilborne pathogens worldwide. Certain strains of these bacteria are capable of exerting a variety of mechanisms of plant growth promotion and protection, including the production of the natural antibiotics 2,4-diacetylphloroglucinol (2,4-DAPG) and derivatives of phenazine (Phz). These compounds are broadly active against plant pathogens and are produced by widely distributed taxonomically diverse Pseudomonas spp. that inhabit the rhizosphere of cereal crops and render certain soils naturally suppressive to soilborne plant diseases. There is mounting evidence that the role of 2,4-DAPG and phenazines in the rhizosphere is not limited to antibiosis but also involves regulatory and signaling functions, induction of systemic resistance, and reduction of minerals in soil.