Summary. The genus Trichoderma comprises a great number of fungal strains that
act as biological control agents, the antagonistic properties of which are based on the
activation of multiple mechanisms. Trichoderma strains exert biocontrol against fungal
phytopathogens either indirectly, by competing for nutrients and space, modifying
the environmental conditions, or promoting plant growth and plant defensive
mechanisms and antibiosis, or directly, by mechanisms such as mycoparasitism.
These indirect and direct mechanisms may act coordinately and their importance in
the biocontrol process depends on the Trichoderma strain, the antagonized fungus,
the crop plant, and the environmental conditions, including nutrient availability, pH,
temperature, and iron concentration. Activation of each mechanism implies the production
of specific compounds and metabolites, such as plant growth factors,
hydrolytic enzymes, siderophores, antibiotics, and carbon and nitrogen permeases.
These metabolites can be either overproduced or combined with appropriate biocontrol
strains in order to obtain new formulations for use in more efficient control of
plant diseases and postharvest applications. [Int Microbiol 2004; 7(4):249-260]