Trichoderma Mechanism

Mechanism of action of Trichoderma

Trichoderma spp. are biocontrol agents effective against fungal phytopathogens. They can act indirectly, by competing for nutrients and space . Biocontrol may additionally result from an immediate interaction among the pathogen itself and the biocontrol agent, as in mycoparasitism. Trichoderma biocontrol agents can promote plant growth and stimulate the plant defense mechanisms (Papavizas, 1985; Howell, 2003; Vinale et al., 2008). The mechanisms can be described as: 3.1.1.1) Competition

Bio control agents and the pathogens compete with one another for the nutrients and space to get established in the environment. This process of competition is considered to be an indirect interaction between the pathogen

It is a complex process which includes chemotropism and recognition; attachment and coiling; cell wall penetration; and digestion of host cell. Initially, the mycoparasite grows directly towards its host and coils around it or attaches to it with the aid of forming hook-like structures and apressoria. Following these interactions, Trichoderma spp. sometimes penetrate the host mycelium, apparently by partially degrading its cell walls (Elad et al., 1984) Subsequently, it is far assumed that Trichoderma spp. utilize the intracellular contents of the host. The key enzymes suggested in the lysis of phytopathogenic fungal cell walls during mycoparasitic action are Chitinases and b-1,3-glucanases proteins secreted by Trichoderma spp. (De la Cruz et al., 1992, Sivan & Chet 1989). The molecular level induction of mycoparasitism was first reported in 1994 (Carsolio et al., 1999), based on the study of regulation of an endochitinase-encoding gene (ech42). Ech42 was expressed during the mycoparasitic interaction between T. harzianum and Rhizoctonia solani. Mycoparasitic Trichoderma species are used commercially as biological control agents against plant-pathogenic fungi inclusive of Rhizoctonia solani, Botrytis cinerea, Sclerotium rolfsii, Sclerotinia sclerotiorum, Pythium spp., and Fusarium spp. in, amongst others, the United States, India, Israel, New Zealand, and Sweden as a promising alternative to chemical pesticides (Howell,