CORE Metadata, citation and similar papers at core.ac.uk Provided by Journal of Applied and Natural Science AL SC R IEN TU C A E N F D O N U A N D D A E I T L I Journal of Applied and Natural Science 8 (2): 1100 - 1109 (2016) O P N P JANS A ANSF 2008 Advent of Trichoderma as a bio-control agent- A review Anita Puyam Department of Plant Pathology, Punjab Agricultural University, Ludhiana-141004 (Punjab), INDIA E-mail: [email protected] Received: September 10, 2015; Revised received: January 17, 2016; Accepted: April 30, 2016 Abstract: Trichoderma spp are free living filamentous fungi. They are cosmopolitan and versatile in nature. They have the potential to produce several enzymes that can degrade the cell wall materials. Also, they release a number of fungi toxic substances that can inhibit the growth of the fungal pathogens. Many mechanisms have been described on how Trichoderma exert beneficial effects on plants as a bio-control agent. But due to its versatile nature, its potential cannot be explored to its full extent. And it is a developing science in the field of bio-control with its new discoveries adding to the usefulness of the fungi as a bio-control agent. Its development as a bio-control agent passes through many phases and each phase adding novel ideas that will help in the development of an efficient bio-agent which in turn will help in the crop improvement and disease management. The studies on their various aspects responsible for bio-control will open a flood gate to the development of Trichoderma as an efficient and reliable bio-agent and provide a better scope for implementation in crop and disease management. The in vitro antagonistic activity of Trichoderma viride against phytopathogens (Sclerotium rolfsii, Fusarium oxysporum f.s.p. ciceri, Fusarium oxysporum f.s.p. udum) was studied and it was found to be potentially effective against F. oxysporum f.s.p. ciceri followed by F. oxysporum f.s.p. udum and Sclerotium rolfsii. Keywords: Antibiosis, Bio-control agent, Mycoparasitism INTRODUCTION the usefulness of this fungus (Lorito et al., 2010). Discovery of bio-control activity mediated by Trichoderma are free living fungi that are highly inter- mycoparasitism: Trichoderma spp. is known for their active in root, soil and foliar environment can parasi- ability to attack and control the plant pathogenic fungi. tize other fungi (Harman et al., 2004). They are asex- Mycoparasitism is one of the most important mecha- ual filamentous fungi who share its anamorph with the nisms that impart bio-control activity. The direct attack genus Hypocreae. They are facultative anaerobes. of one fungus on another or direct antagonism is They are versatile, highly rhizosphere competent, pro- known as mycoparasitism (Dix and Webster, 1995). fuse root colonizers and cosmopolitan in nature. They This concept dates back to the work of Weindling are also opportunistic avirulent plant symbionts. They (1932) who demonstrated the parasitism of Rhizocto- are known for prolific production of extracellular nia solani hyphae by the hyphae of Trichoderma proteins and fungitoxic substances. They have been virens in controlling citrus seedling disease. Other re- utilized extensively as model microorganisms to searchers also showed the mycoparasitism of Tricho- analyze and improve the understanding of the role that derma spp towards Pythium ultimum and Sclerotium these antagonistic fungi have been playing in biologi- rolfsii (Papavizas, 1985). Mycoparasitism is a sequen- cal interactions, for instance with crop plants and tial and complex process, involving three steps: phytopathogens (Marra et al., 2006). They have been chemotrophic growth and recognition; coiling and in- gaining momentum as an important biocontrol agent teraction of hyphae and secretion of specific lytic en- (BCA) in control of plant diseases in recent times due zymes (Dix and Webster, 1995). to its eco-friendly nature, minimizing the use of chemi- Chemotrophic growth and recognition: The chemi- cals, giving more cheaper and efficient disease control cal stimuli released by the target fungus are first sense method. Intensive researches have been going on the by Trichoderma through their specific signaling complex mechanisms, among which, the most mechanism. This mediates the growth of Trichoderma important being induction of host defense besides towards the target fungi. Apparently, Trichoderma producing large amount of heterologous proteins, releases low levels of extracellular exochitinase effecting plant metabolism and physiology. Because of induced by the cell-wall oligomers of the target fungi the certain beneficial effects, Trichoderma has been and endochitinase gene is activated when interact with gaining popularity as one of the most important bio- the target fungus. Ultimately, all these action induces control agent. Their journey towards bio-control passes the released of fungitoxic cell wall degrading enzymes through many phases with new discoveries adding to ISSN : 0974-9411 (Print), 2231-5209 (Online) All Rights Reserved © Applied and Natural Science Foundation www.ansfoundation.org Anita Puyam / J. Appl. & Nat. Sci. 8 (2): 1100 - 1109 (2016) 1101 (CWDEs) from Trichoderma viz. extracellular β-(1, 3)- by the Trichoderma colonization (Corke and Hunter, glucanase, proteases, lipases and chitinases (Viterbo et 1979).They can proliferate in the soil and out beat the al., 2007). growth of other soil micro-flora. They can compete for Coiling and interaction of hyphae: As Trichoderma nutrients, space, water or oxygen against other soil established contact, it starts coiling around and form micro-flora. They have the capacity to mobilise and appressoria for attachment mediated by carbohydrate take up soil nutrients compare to other organisms. (from the cell-wall of Trichoderma) and lectin (from Also, they are resistant to a variety of toxins produced the target fungus) complex (Howell, 2003). by other micro-organisms and other anti-microbial Secretion of specific lytic enzymes: Several fungi- substances produced by the plants due to the presence toxic CWDEs and peptaibol antibiotics are produced of ATP-binding cassetts (ABC) transporters that re- by the Trichoderma induced by the cell wall materials duce the toxic effects. This enhances the competitive of the target fungus. This induces a cascade of physio- ability against other micro-organisms.Competition for logical changes within the fungus. Due to action of carbon has also been involved in the determination of these CWDES holes are produced in the hyphae of the antagonism expressed by different strains of target fungus near the site of appressoria. The antago- Trichoderma sp. against several plant pathogens, espe- nistic hyphae grow along the host hyphae and secrete cially F. oxysporum (Sivan and Chet, 1989). Tjamos et different lytic enzymes such as glucanase, chitinase al. (1992) demonstrated that T.harzianum T-35 con- and pectinase that are involved in mycoparasitism. trols Fusarium oxysporum by competing for both This ultimately leads to the degeneration of the target rhizosphere colonization and nutrients. Some Tricho- fungus (Howell, 2003). derma spp produce highly efficient low molecular Discovery of bio-control activity mediated by weight ferric iron specific chelators termed as antibiosis: Weindling (1934) proposed “lethal princi- siderophores to mobilize or chelate environmental iron ple”. This gave a shift to the concept of mycopara- and stop the growth of other fungi (Chet and Inbar, sitism. According to which, besides showing myco- 1994). Chet et al. (1997) reported that starvation of parasitic activity, Trichoderma do produced certain pathogen due to limiting nutrients results in its death. lethal factors in the soil that inhibits the growth and the But, cruciality in viewing competion as primary role in development of the pathogenic fungi. Later, in 1941, bio-control is that T. koningii, which is an excellent he showed that the factor behind the lethal principle is root colonizer when treated against R. solani, there is Gliotoxin secreted by Trichoderma virens. This led to little or no bio-control (Howell, 2003). These findings the development of another mechanism behind the bio- again gave an enigma to the Trichoderma researchers control potential i.e. antibiosis. Trichoderma produces on how Trichoderma interact with the plant, the target low molecular weight diffusible compounds or antibi- pathogen and its environment. otics possessing antifungal and antibacterial proper- Discovery of the ability to improve plant resistance ties.These substances can penetrate the host cell, in- to diseases: Strains of Trichoderma added to the hibit cell wall synthesis of the target fungus (Lorito et rhizosphere protect plants against pathogens those that al., 1996).They also inhibit the growth, uptake of nutri- produce aerial infections, including viral, bacterial and ents, sporulation, production of metabolites of the tar- fungal pathogens, which point to the induction of resis- get fungus (Wilcox et al., 1992; Howell, 1998). Anti- tance mechanisms similar to the hypersensitive re- biosis is species specific i.e., different strains exhibit sponse (HR), Systemic acquired resistance (SAR) and different antifungal activity (Howell et al., 1993). Induced Systemic Resistance (ISR) in plants (Harman Howell and Stipanovic (1983) isolated gliovirin from et al., 2004). The concept of improving plant resis- T.virens that inhibited Pythium ultimum and Py- tance by Trichoderma is the most accepted phenomena thophthora.