Use of plant growth-promoting rhizobacteria as biocontrol agents: induced systemic resistance against biotic stress in plants

Abstract

Plant growth-promoting rhizobacteria (PGPR) are free-living bacteria able to colonize roots and soil around them that have a positive effect on plant growth, development, and health. One of the mechanisms by which PGPR exert a beneficial effect involves the capacity to control growth of deleterious organisms diminishing or preventing their negative effects on plant health and growth. Pathogen biocontrol implicates diverse features of bacteria; one of them is the antagonism that excludes pathogen due to the ability of some bacteria to colonize faster and more effectively a niche, reducing nutrient availability for the deleterious organism. Also some bacteria produce antibiotics, organic compounds that are lethal in low concentration for growth and metabolic activities of other microorganisms. Finally, the ability of bacteria to elicit a defense response in plant, called induced systemic resistance (IRS), involves the induction of synthesis of defense metabolites, but without causing a disease itself, enhancing the plant´s defensive capacity. This chapter analyzed and discussed PGPR as biocontrol agent and the possibility to use them as ecological alternative to the use of agrochemicals, since they have been proved in different plant species in order to diminish the damage of pathogen and to reduce losses in crops.