Chapter 24 - Secondary metabolites and lytic tool box of trichoderma and their role in plant health

Abstract

With expanding population, unbridled use of chemicals, deteriorating environment and soil health, it is required that the management approaches for plant diseases which take a heavy toll on the crop produce each year should be sustainable, environment friendly and economical. Therefore, effective biological control measures which could be integrated with existing management tactics is the need of the hour. A miraculous ascomycetous fungi genus, Trichoderma (Teleomorph Hypocrea) holds the topmost rank in the list of fungal biocontrol agents (BCA) and therefore has fascinated scientists from all across the globe because of its biocontrol potential against many phytopathogenic fungi. The mechanisms underlying the biocontrol ability of this fungus include mycoparasitism, competition for nutrients and space, antibiosis, induction of systemic or local resistance in the host plants. This chapter reviews an array of secondary metabolites produced by Trichoderma spp. The major classes of secondary metabolites are: Non-Ribosomal Peptides (Peptaibols, Epipolythiodioxopiperazines, Siderophores), Polyketides (Pyrones, Koninginins), Terpenes/Terpenoids (Sesquiterpenes, Trichothecenes, Viridin), Anthraquinones. Different secondary metabolites isolated produced by Trichoderma spp. along with their brief history, structural and functional characteristics as well as their regulation mechanism has been discussed under subheadings in this chapter. The reader will also get an overview of the basic regulation mechanism of secondary metabolite synthesis that is governed by biosynthetic gene clusters that encode large multidomain and multimodular core enzymes. At the end the chapter also describes the various beneficial effects of this wonder genus on plants.