The genus Trichoderma consists of more than 104 species of filamentous green-spored ascomycetes which are widely distributed in soil and other habitats. They commonly occur on root surfaces of plants, decaying bark, other organic materials, and are practically ubiquitous. They have been studied with respect to various
characteristics and applications and are known as successful colonizers of their habitats, efficiently fighting their competitors. They are rarely associated with diseases of living plants, although an aggressive strain of T. harzianum causes a significant disease of commercial mushrooms causing green mold disease.3,5
Main conidiophores produce smaller side branches with a conifer-like branching system formed; all the branches stand at wide angles to the bearer; conidia are globe-like, bluish green to dark green.
The use of eco-friendly biocontrol agents is increasingly being stressed as an important component of the integrated pest management. Among the many biocontrol agents available, species of Trichoderma have proved to be useful in controlling seed- and soil-borne pathogens. These are fascinating fungi which produce a number of cell wall degrading enzymes such as chitinase, endoglucanase, cellulase, protease, and antibiotics which inhibit growth of other fungi.
The beneficial action of Trichoderma species is not limited to fighting pathogens, they have also been shown to be protectors of plant health. These fungi colonize and penetrate plant root tissues and initiate a series of biochemical changes in the plant, which are considered to be part of the plant defense response. Trichoderma species are reported and known to induce growth of various crops.2
Due to their metabolic versatility, many Trichoderma species are resistant to herbicides, pesticides, and antibiotics produced by other organisms which allows them to grow easily under extremely competitive conditions. some species are able to degrade hydrocarbons, chloro-phenolic compounds, polysaccharides and other harmful chemicals, and these abilities make them a potential tool for bioremediation.1 The cellulases produced by Trichoderma reesei, the biotechnological workhorse of
the genus, are important industrial products, especially with respect to production of second generation biofuels from cellulosic waste.5
Trichoderma species have long been known as non-harmful microorganisms. However, as recently emerging fungal pathogens, Trichoderma strains have been detected on the skin, in the lung and as causative agents of peritonitis in peritoneal dialysis patients, and have been found to be disseminated in the liver, brain, heart and stomach of immunocompromised patients. The majority of the pathogenic Trichoderma isolates are members of the species T. longibrachiatum which is resistant antifungal therapy.4
- Applied Mycology. Mahendra Rai, P. D. Bridge
- Management of Fungal Plant Pathogens. Arun Arya, Analía Edith Perello.
- Trichoderma and Gliocladium: Basic biology, taxonomy, and genetics. Christian P. Kubicek, Gary E. Harman, Kristen L. Ondik
- Changing epidemiology of systemic fungal infections. M. Richardson, C. Lass-Florl
- Biology and biotechnology of Trichoderma. Andre Schuster & Monika Schmoll
Microscope photography courtesy of Larysa Johnston