Trichoderma Fungi as a Biopesticide in Agriculture

Overview of Trichoderma

Trichoderma is a natural fungus that is commonly employed for managing pests in plants. This fungus can be found primarily in the soil, air, on plant surfaces, and in different ecological settings, and it is capable of effectively managing several plant diseases. Trichoderma helps to avoid diseases, encourages the growth of plants, boosts the efficiency of nutrient usage, strengthens plant resistance, and aids in the recovery from chemical pollution in agriculture.

Trichoderma is a genus of fast-growing, filamentous fungi commonly found in soil, decaying wood, and plant roots. It is known for its rapid colony growth, producing white mycelium that turns green due to conidia formation. Microscopically, it has branched conidiophores, flask-shaped phialides, and green, round to oval conidia.

These fungi thrive in a wide range of environmental conditions, with an optimal growth temperature of 25–30°C and a pH range of 4.0–7.5. Trichoderma is highly adaptable and produces various hydrolytic enzymes, including cellulases, chitinases, and proteases, which contribute to its ability to decompose organic matter and interact with plant-associated microorganisms.

More than 370 species of Trichoderma exist, such as Trichoderma harzianum, Trichoderma viride, Trichoderma asperellum, Trichoderma hamatum, Trichoderma atroviride, Trichoderma koningii, Trichoderma longibrachiatum, and Trichoderma aureoviride. In research on biological control, Trichoderma has been utilized, particularly Trichoderma harzianum, Trichoderma hamatum, Trichoderma longibrachiatum, Trichoderma koningii, Trichoderma viride, Trichoderma polysporum, and Trichoderma asperellum.

Various studies indicate that many Trichoderma species have the ability to produce bioactive compounds and exhibit antagonistic properties against fungi that harm plants and nematodes that attack plants. These bioactive compounds, such as secondary metabolites and enzymes that break down cell walls, can significantly enhance the resistance of crops, lessen plant diseases, and aid in the growth of plants.

Mechanism of Action of Trichoderma as a Biopesticide

Mycoparasitism of Trichoderma

Mycoparasitism is an important biological method for managing Trichoderma. This process involves the direct invasion or destruction of the mycelium, which causes alterations in the cells of the pathogen, resulting in changes like expansion, deformation, shortening, rounding, shrinking of protoplasm, and rupture of cell walls.
Trichoderma can effectively destroy the cell walls of harmful fungi by producing enzymes that break down chitin. This action helps them enter the interior of these fungi more easily. The chitinase generated by T. harzianum plays a crucial role in breaking down cell walls, facilitating the self-destruction of the mycelium, aiding in chitin absorption, allowing for fungal parasitism, and inhibiting spore germination, mycelial growth, and spore production.

Antibiosis effect of Trichoderma

Antibiosis primarily describes how Trichoderma can stop harmful fungi that attack plants from growing by releasing substances that fight them. Trichoderma has the capability to create many antimicrobial compounds, such as trichomycin, gelatinomycin, chlorotrichomycin, and peptides that kill bacteria. These compounds can serve as agents against bacteria, help in the growth of plants, and offer valuable resources for creating agricultural antibiotics.

Induced systemic resistance of Trichoderma

Mycoparasitism is an important biological method for managing Trichoderma. This process involves the direct invasion or destruction of the mycelium, which causes alterations in the cells of the pathogen, resulting in changes like expansion, deformation, shortening, rounding, shrinking of protoplasm, and rupture of cell walls.

Trichoderma can effectively destroy the cell walls of harmful fungi by producing enzymes that break down chitin. This action helps them enter the interior of these fungi more easily. The chitinase generated by T. harzianum plays a crucial role in breaking down cell walls, facilitating the self-destruction of the mycelium, aiding in chitin absorption, allowing for fungal parasitism, and inhibiting spore germination, mycelial growth, and spore production.

**Applications of Trichoderma in Agriculture**

Biological Control Agent

Species of Trichoderma function as natural enemies against a variety of plant diseases through methods such as mycoparasitism, antibiosis, and competing for nutrients.
It effectively manages fungal infections brought on by Fusarium, Rhizoctonia, Pythium, Sclerotinia, Phytophthora, and Botrytis. This serves as an environmentally friendly substitute for chemical-based fungicides.

Promotion of Plant Growth

It generates plant hormones (such as auxins) that encourage the growth of roots and shoots. This improves seed germination, strengthens seedlings, and increases overall plant mass.

Inducing Systemic Resistance

Trichoderma encourages systemic resistance within plants, helping them to better withstand both biotic and abiotic pressures.
It triggers defense mechanisms in plants by boosting the production of enzymes and secondary metabolites that aid in defense.

Solubilization of Phosphate and Nutrients

It aids in making phosphorus and other key nutrients more available for plants by solubilizing them. This boosts the efficiency of nutrient uptake, lessening reliance on chemical fertilizers.

Breakdown of Organic Matter

The species of Trichoderma decompose organic materials which improves soil health. It enhances the composting process by speeding up the breakdown of plant debris and organic waste.

Bioremediation

Trichoderma is employed in soil bioremediation processes to break down pesticide leftovers and other toxic substances. This enhances soil quality and structure, supporting sustainable farming practices.

Seed Treatment and Soil Application

Trichoderma blends are used for coating seeds to shield them from pathogens in the soil. They are applied as biofertilizers or biopesticides in both soil and leaf sprays.

Reference and Sources:

https://www.intechopen.com/chapters/1170606
https://pmc.ncbi.nlm.nih.gov/articles/PMC8875981/
https://www.sciencedirect.com/science/article/pii/B9780323917346000120

Trichoderma: Overview, Mechanism of Action and Applications