Question

Trichoderma harzianum is useful for
A. Gene transfer in higher plants
B. Biological control of soil borne pathogens/biopesticide
C. Bioremediation of contaminated soils
D. Reclamation of waste lands

Answer 1

Hint: Trichoderma is one of the most commercially important microorganisms in agriculture and industry. Trichoderma species are used for various purposes in the cultivation of agricultural crops. Trichoderma associates with other microorganisms, but primarily pathogenic fungi.

Complete answer:
- Trichoderma is a genus of soil-dwelling fungi found all over the world that are highly successful in colonising many kinds of plant roots and inhibiting fungal diseases. It was one of the first commercially available forms of biofungicides.
- Trichoderma is successful for use as a biocontrol agent in various fungal pathogens and in certain bacterial pathogens. One strain, in particular, T. Harzianum (T-22) can form a close relationship with the roots of the plant and colonise them. This invasion puts the fungus in a good position to outdo and parasitize other fungi in the soil.
- When Trichoderma has colonised its roots, it can boost development in two major ways. First of all, it destroys the fungi that cause root rot. Second, it prevents the roots from any physical stress, helping the roots to expand faster.

- Trichoderma destroys a variety of large root rot fungi: Pythium, Rhizoctonia, and Fusarium. This mechanism is called mycoparasitism. Trichoderma produces enzymes that dissolve the cell walls of the other fungi. It will get inside the bad fungi and consume them.
- The strain used in T-22 secretes even more of the main enzyme, endochitinase, than wild strains, so T-22 grows faster and secretes more of the enzyme than wild strains. This allows crop roots to be protected from root rot fungi in the field.

Thus, the correct answer is option B i.e., Biological control of soil borne pathogens /biopesticide.

Note: The Trichoderma genus is genetically very diverse and has a wide range of capabilities amongst different strains of agricultural and industrial value. Potential Trichoderma decreases pollutants by acting on contaminants by the action of different enzymes and increases the physical and chemical properties of the soil.