All the economically important crops are damaged by the pathogens

All the economically important crops are damaged by the pathogens, fungi is the most aggressive soilborne pathogens, which have been extremly investigated due to damage to our crops. The main pathogenic fungal genera are: Phythium, Botrytis, Rhizoctonia and Fusarium (Djonovi?, Vargas et al. 2007). Pesticides have been widely used to control these pathogens (Gerhardson 2002); But their applications have been resulted in environmental and human health concerns throuhout the world (Punja and Utkhede 2003; Buès, Bussières et al. 2004). So, chemical control of these pathogens is ineffective, unless highly selective fungicides are used.
Cell walls of Trichoderma spp. produce hydrolytic enzmes such as cellulase, chitinase etc., which play an important role in degradation of biomass (used in production of chemicals) (Schuster and Schmoll 2010). (Chet 1987) studied that, cell wall of phytopathogenic fungi are composed of ?-1,3-glucans and chitin, including cellulose in some oomycetes such as Pythium spp., but due to the presence of hydrolytic enzymes Trichoderma spp. intrefeare the activity of pathogen, thus acting as a ecofriendly biocontrol agent. Hydrolytic enzmes that are secreted by the Trichoderma spp. mainly inhibit the growth of pathogens (Asad, Ali et al. 2014). E.g. Trichoderma harzianum produce hydrolytic enzymes that inhibit the growth of Crinipellis perniciosa, the causative agent of cocoa (Theobroma cacao) disease (Marco, Valadares-Inglis et al. 2003). The most important factor for enzyme production is the type of carbon source available for the fungus. Production of hydrolytic enzymess are also dependent on light conditions, growth rate, and secretion stress (Martinez, Berka et al. 2008; Arvas, Pakula et al. 2011; Tisch and Schmoll 2013).
Trichoderma isolates produce hydrolytic enzymes such as chitinases, ?-1,3- and ?-1,6-glucanases, and proteases (?-1,3-glucan), chitin, or fungal cell walls as the carbon source (Elad, Chet et al. 1982; De La Cruz, Rey et al. 1993). Trichoderma reesei is the most widely employed cellulolytic producer of Cellulose- and hemicellulose-degrading enzymes and is used as a production host for enzymes in industrial applications. The large number of carbohydrate active enzymes produced by T. reesei (Häkkinen, Arvas et al. 2012) form a complex system that is regulated by a variety of environmental and physiological factors. The generation of high cellulase-producing mutants from the wild-type. Trichoderma reesei strain QM6 was found to be good producer of hypercellulolytic enzyme, (RUT-C30) (Peterson and Nevalainen 2012), although high levels of cellulase are also produced in other species from this genus (Baig, Mane et al. 2003; Watanabe, Akiba et al. 2006). The use of Trichoderma harzianum species in biotechnology has been explored by examining the biocontrol capacity of this species (Liu and Yang 2005; Yao, Yang et al. 2013). T. hamatum strains possess higher antimicrobial activity due to presence of specific ?-glucanase and chitinases, which play important roles as hydrolytic enzymes during cell wall degradation (Cheng, Song et al. 2015).(Cheng, Liu et al. 2017) studied that YYH13 strain of T. hamatum produce cellulase, due to its strong ability to degrade cellulosic biomass (De La Cruz, Rey et al. 1993; JESU´S DE LA CRUZ 1995). (Ahmed, Bashir et al. 2009) studied the production and purification of three cellulases from Trichoderma harzianum: exoglucanase (EXG), endoglucanase (EG) and ?-glucosidase (BGL). Small number of cellulases is present in T. reesei, T. virens and T. atroviride; But all thsese spp. are enriched in some hemicellulolytic components, such as GH27 ?-galactosidases, GH43 ?-arabinofuranosidases/?-xylosidases, GH67 and GH79 ?-methylglucuronidases and ?-fucosidases, cellulase and xylanase (Kubicek 2013)
Trichoderma spp. are able to use a wide range of compounds as carbon and nitrogen sources and secrete a variety of enzymes to breakdown plant polymers into simple sugars for energy and growth. Owing to the high cost of chemical inducers for these enzymes, there is a need to look out for organic inducers from agriculture wastes so as to increase the mass production of Trichoderma species. Studies of enzymes produced by Trichoderma are necessary to find more efficient and low-cost enzymes, which are useful in different steps of the hydrolytic process of biomass degradation.


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