Biological control of peronosporomycete phytopathogen by bacterial antagonist

Abstract

Peronosporomycetes are devastating pathogens to numerous crop, ornamental, and native plants. They are phylogenetically distinct from those of fungi and hence most of the fungicides are ineffective against them. A large body of literature reveals that several bacterial genera such as Pseudomonas, Bacillus, Burkholderia, Lysobacter, Enterobacter, etc. exert antagonistic activities against the peronosporomycete phytopathogens in both in vitro and in vivo conditions. These bacterial strains originated from diverse habitats and some of them showed high promise for biocontrol of plant diseases caused by these notorious pathogens. Mechanisms of biocontrol by these bacterial antagonists include (1) antibiosis, including biosurfactant activity, (2) secretion of lytic enzymes, (3) competition for nutrients (C and Fe), (4) high plant and hyphal colonization, (5) hyperparasitism, and (6) development of induced systemic resistance in the host plants. This chapter comprehensively reviews advances of research on biocontrol of peronosporomycete phytopathogens by bacterial antagonists including the mode of actions of the antagonistic principles against the pathogens. Recent advances on genome sequencing of several peronosporomycetes and biocontrol agents will provide basis for better understanding of bacteria-plant-pathogen interactions and development of improved strains that will potentially function as effective biocontrol agents against the notorious peronosporomycete phytopathogens for low input sustainable agriculture.