Phenazine-producing pseudomonas spp. as biocontrol agents of plant pathogens

Abstract

Soils that are suppressive to diseases have often been shown to contain high levels of fluorescent Pseudomonas spp. that produce a variety of secondary metabolites, including antibiotics such as hydrogen cyanide, diacetylphloroglucinol (DAPG) and phenazines, among others. Phenazine-producing Pseudomonas spp. show promise for use as successful biocontrol agents against many diseases affecting several agricultural crops. The production of different types of phenazines (phenazine-1-carboxylic acid (PCA), phenazine-1-carboxamide (PCN), hydroxyphenazines (OH-PHZ) and pyocyanin (PYO)) has been shown to be directly involved in the reduction of several diseases caused by fungi, oomycetes and bacteria, in a variety of geographical locations. Phenazines can also be highly important in fluorescent Pseudomonas spp. physiology and have the potential to increase fitness of the producing strains by affecting traits such as biofilm formation and iron acquisition. The high capacity for soil colonization as well as the robustness and competitiveness of fluorescent Pseudomonas spp. show potential for their increased use in commercial applications. However, further studies are needed to determine the optimal conditions under which these bacteria can persist and produce phenazines under natural soil conditions, and their implication at the molecular, physiological, and ecological levels.