This process of mycoparasitism limits growth and activity of plant pathogenic fungi. Different species of Trichoderma have the potential to control soil-borne plant pathogens more effectively than chemicals and they also exhibit plant-growth promoting activity (Harman & Bjorkman 1998). These fungi grow tropically toward hyphae of other fungi, coil about them in a lectin-mediated reaction, and degrade cell walls of the target fungi by the secretion of different lytic enzymes. We do not know if most of the benefits of Trichoderma occur because they directly attack and control disease-causing fungi, as has long been believed, or because they have direct effects upon plants. Many recent findings suggest that plant development and biochemistry are strongly affected by Trichoderma strains. Specific strains of Trichoderma colonize and penetrate plant root tissues and initiate a series of morphological and biochemical changes in the plant, considered to be part of the plant defense response, which in the end leads to induced systemic resistance in the entire plant. They can also compete with other microorganisms for example, they compete for key exudates
from seeds that stimulate the germination of propagules of plant-pathogenic fungi in soil and, more generally, compete with soil microorganisms for nutrients and/or space. Furthermore, they inhibit or degrade pectinases and other enzymes that are essential for plantpathogenic fungi. This review aims to give a broad overview on the qualities and versatility of Trichoderma species and to highlight intriguing findings as well as promising applications.