Fungal Antibiosis in Biocontrol of Plant Disease

The implication of antibiotics and enzymes of fungal origin in biocontrol has been extensively investigated, but only in a few cases has their role been conclusively elucidated. Production of the antifungal epidithiadiketopiperazine metabolites chaetomin and gliotoxin by the soil-inhabiting biocontrol fungi, Chaetomium globosum and Gliocladium virens, respectively, has been shown to be of importance in biocontrol. Recently, the antifungal properties of purified chitinolytic and glucanolytic enzymes from the biocontrol fungi Trichoderma harzianum and G. virens have been described, and evidence has been provided that these cell wall-degrading enzymes may act synergistically with antibiotics. Recombinant DNA technology, allowing the construction of genetically modified biocontrol agents will be useful for evaluating the role of specific compounds in biocontrol and for creating improved biocontrol organisms. Potential applications of this approach in future biocontrol practice is discussed.