Selecting, monitoring, and enhancing the performance of bacterial biocontrol agents: Principles, pitfalls, and progress

Abstract

Genetic resistance to root diseases of plants is rare, and agriculture controls these diseases through practices such as crop rotation and soil fumigation. However, plants have evolved a strategy of stimulating and supporting specific groups of antagonistic rhizosphere microorganisms as a defense against diseases caused by soilborne pathogens. Antibiotic production has a significant role in plant defense by many of these rhizobacteria. Information now is available about the genetics, biochemistry, and regulation of synthesis of some of the most commonly-produced antibiotics. Similarly, many genes that contribute to the ability of these bacteria to colonize roots have been identified. Studies of naturally suppressive soils have provided evidence of preferential interactions between plant hosts and protective populations, revealing the existence of functional diversity among otherwise almost indistinguishable strains. Here, we consider how this knowledge can be applied to aid in the selection of more effective biological control agents and the development of recombinant strains that may overcome impediments to inoculum preparation, formulation, and cost that currently limit commercial acceptance of highly promising candidate strains. © 2007 Springer.