Biological control of plant root pathogens.

Rhizobacteria introduced to control soil-borne root diseases must establish metabolically active populations that mediate protection either by direct antagonism of pathogens or by stimulation of host plant defenses. Recent interest has focused on the genetic and biochemical basis of disease control and the influence of environmental factors on the expression and activity of biocontrol mechanisms. The cloning and sequencing of genes involved in the production of microbial metabolites playing key roles in plant defense opens new possibilities for improving the performance of biocontrol agents.