Chapter 13 - The role of Trichoderma fungi in inducing defense mechanisms in plants

Abstract

Various interactions, both beneficial and harmful, occur between microorganisms and plants at many trophic levels. Plants must fend off attack from phytopathogenic microorganisms and other pests and recognize antagonists (beneficial microorganisms) colonizing the phyllosphere and rhizosphere in both natural and agricultural systems. Plants activate appropriate defense mechanisms, including induced systemic resistance and systemic acquired resistance, mediated by plant growth–promoting bacteria and fungi. Phytohormones such as ethylene, jasmonic acid, and salicylic acid play as key modulators in the induction of immune mechanisms in plants. In the early stages of root colonization by pathogenic or nonpathogenic microorganisms, they are involved in transmitting “alarm signals” triggering many metabolic changes in the plant, including increased production of metabolites and proteins such as pathogenesis proteins as well as peroxidases and phytoalexins, accumulation of hydrolases (chitinase and -1,3-glucanase), and deposition of structural polymers (lignins and glycoproteins).