Chetan Keswani

Unraveling the efficient applications of secondary metabolites of various Trichoderma spp.

Recent shift in trends of agricultural practices from application of synthetic fertilizers and pesticides to organic farming has brought into focus the use of microorganisms that carryout analogous function. Trichoderma spp. is one of the most popular genera of fungi commercially available as a plant growth promoting fungus (PGPF) and biological control agent. Exploitation of the diverse nature of secondary metabolites produced by different species of Trichoderma augments their extensive utility in agriculture and related industries. As a result, Trichoderma has achieved significant success as a powerful biocontrol agent at global level. The endorsement of Trichoderma spp. by scientific community is based on the understanding of its mechanisms of action against a large set of fungal, bacterial and in certain cases viral infections. However, it is still an agnostic view that there could be any single major mode of operation, although it is argued that all mechanisms operate simultaneously in a synchronized fashion. The central idea behind this review article is to emphasize the potentiality of applications of target specific secondary metabolites of Trichoderma for controlling phytopathogens as a substitute of commercially available whole organism formulations. With the aim to this point, we have compiled an inclusive list of secondary metabolites produced by different species of Trichoderma and their applications in diverse areas with the major emphasis on agriculture. Outlining the importance and diverse activities of secondary metabolites of Trichoderma besides its relevance to agriculture would generate greater understanding of their other important and beneficial applications apart from target specific biopesticides.

A Superstar in Biocontrol Enterprise: Trichoderma spp

The role of biocontrol agents (BCAs) is a well established fact and has become increasingly crucial in replacing the chemical pesticides for plant pathogen control. Currently, Trichoderma spp. share almost 70% of fungal BCAs market. Trichoderma is a potential biocontrol agent included in the gazette of India on 26th March 1999. Trichoderma harzianum is extensively used for its twin advantages of controlling several soil and seed borne phytopathogens in addition to its capacity to act as an effective biofertilizer. Competence of Trichoderma spp. to other fungal biocontrol agents owes to its relatively faster metabolic rates; secretion of anti-microbial secondary metabolites and physiological conformation are some of the key factors which contribute to its vigorous antagonistic effect in field conditions. On the other hand, Trichoderma spp. has also been exploited for commercial production of enzymes like cellulases, hemicellulases, proteases, and â-1, 3-glucanase. This article advertises the commercial potential of Trichoderma spp. discussing its status in various aspects viz., pest control, plant growth promotion, bioremediation and production processes.

Trichoderma spp.: Efficient Inducers of Systemic Resistance in Plants

Defense response in plants, triggered by biocontrol agents (BCAs), is an intensively investigated area. In recent past, various agriculturally important microorganisms have been identified and described as efficient inducer of systemic resistance in plant. Trichoderma spp. are established plant root colonizers and their biocontrol nature is primarily due to mycoparasitism and antibiosis mechanisms against various pathogens. Progress in research in plant immunity induced by beneficial microorganisms suggests that other than mycoparasitism and antibiosis, Trichoderma spp. are potent inducers of ISR in plants. There is need for more intensive studies aimed at gaining insight into the signal transduction pathways and defense responses elicited by Trichoderma. Furthermore, quick progress in molecular studies will lead to gain deeper insight into the regulation of complex interaction between plant and biocontrol agents and increase the efficiency of currently existing biocontrol strategies and plant disease management modules.

Agriculturally Important Microorganisms

Plants have been inoculated with plant growth-promoting microorganisms to enhance crop yield and performance over four decades. The two central aspects for success of inoculation are the effectiveness of the bacterial strain and the application technology. This chapter discusses characteristics of ideal carriers for bacterial inoculants [plant growth-promoting bacteria (PGPB) and plant growth-promoting rhizobacteria (PGPR)] and focuses on superior formulations for the future, mainly polymeric and encapsulated formulations and new emerging ideas in the fi eld of inoculation. Future research avenues are highlighted.

Formulation Technology of Biocontrol Agents: Present Status and Future Prospects

Recent shift in trends of agricultural practices from application of synthetic fertilizers and pesticides to organic farming has brought into focus the use of microorganisms those carryout analogous functions. Formulations of rhizomicroorganisms available in global markets range from talc-based and liquid and secondary metabolite-based formulations. The ideal conditions required for development of high efficiency formulations of biopesticides include selection of potent strains, shelf life, storage, application technology, quality control, biosafety, and registration. In this chapter, we will discuss the constraints associated with development and commercialization of bioinoculants. Moreover, special emphasis will be on the next generation of antimicrobial secondary metabolite formulations which will not only have a much longer shelf life but also a higher efficiency against soilborne phytopathogens particularly against bacteria; also, a consortium of antimicrobial metabolites against individual pathogens could be formulated and used regardless of geographic location where the incidence of that particular disease is high. This approach would be unsurpassed by current technology, as the formulation would specifically target a particular pathogen while remaining soil microbiota would remain unaffected.

Nanotechnology: Exploring potential application in agriculture and its opportunities and Constraints

Nanotechnology has emerged as the most innovative and revolutionary scientific field in decades that deals with matter in the range of nanoscale (1–100 nm). These nanoscale materials, commonly called as nanoparticles (NPs), exhibit unique physical, chemical and biological properties. The great potential of NPs has been explored to a large extent in multifarious fields such as medical, electronics, cosmetics and environmental remediation for societal benefits. However, the full potential of nanotechnology in agricultural sector is still budding and yet to be explored. After unsustainable approach of green revolution, recently nanoparticles based strategy is gaining considerable attention in agriculture owing to its unique properties, as compared to biopesticides leading to nano-revolution for maintaining sustainability in agriculture. Undoubtedly, nanotechnology in agriculture is the unexplored area which is expected to expand in the coming years. Besides expecting excellent applications of nanotechnology in agriculture, there are some biosafety issues which need to be addressed in future research endeavor. In this regard, the present review deals with both opportunities and constraints of nanotechnological applications in agriculture.

A Proteomic Approach to Understand the Tripartite Interactions Between Plant-Trichoderma-Pathogen: Investigating the Potential for Efficient Biological Control

Efficient biological control of plant diseases involves successful interactions among plant, biocontrol agents, and pathogens. Trichoderma spp. being the most popular and successful biocontrol agents are predominantly used to protect plants against a broad range of phytopathogens. However, a better understanding of the tripartite relationship established among Trichoderma-plant-pathogen is necessary in order to advance the practical applicability in agroecosystems and to unveil the cross talk involved in this beneficial association. Moreover, comprehensive knowledge of this three-way association is also required to identify the effective strain of Trichoderma to be used for efficient plant disease control. In this regard, several approaches have been adapted to study these tripartite interactions at molecular level such as transcriptomics, proteomics, and metabolomics. Although transcriptomic approach generates huge data, the study is incomplete without involving proteomic aspect, as it is directly responsible for cellular activity. Therefore, implication of proteomics in studying plant-pathogen interaction is now gaining noteworthy attention. Recently, proteomic approach has been found to contribute successfully in recognizing and characterizing the major proteins playing key role in inducing the defense mechanism in plants against pathogen attack. Nevertheless, empathizing proteomics of Trichoderma spp. can be used to discover novel determinants that would be helpful in developing new biocontrol formulation with enhanced biocontrol potential. Moreover, strain improvement using such determinants could also be achieved. In addition, proteomic study of the pathogen in this interaction is of great interest, as it would give insight into two aspects: firstly, the major factors contributing to the pathogenicity and secondly, targeting such factors for diminishing the pathogenicity. Therefore, in this chapter we focus our attention on highlighting the recent advances and findings regarding the proteomic approach used to study tripartite interaction between Trichoderma-plant-pathogen.

Beauveria bassiana: Biocontrol Beyond Lepidopteran Pests

Beauveria bassiana has been extensively employed since the last century for biocontrol of lepidopteran pests. B. bassiana has also been explored for diverse functions including bioremediation of toxic industrial effluents and heavy-metal polluted soils. Investigations on multifarious applications of chemically diverse secondary metabolites of this entomopathogenic fungus offer promising implications in pharmaceutical and agricultural sectors. In addition, the development of eco-friendly bioremediation strategies using abiotic stress-tolerant strains of B. bassiana will contribute to maintain the sustainability of agroecosystem.

Biocontrol Technology: Eco-Friendly Approaches for Sustainable Agriculture

Abstract Recent advances in structural and functional genomics are having penetrating impact on human and environmental health. As a potential alternative of hazardous chemical pesticides, agriculturally important microorganisms have gained popularity throughout the globe. There are various naturally occurring soil microbes that aggressively attack and destroy soil and seed-borne plant pathogens, hence referred as biocontrol agents that comprise members from bacterial, fungal, and viral genera. These biocontrol agents exhibit multiple beneficial characters such as plant growth promotion activity by secretion of various plant growth promoting hormones and by mobilization of many essential inorganic macro- and micronutrients, therefore commonly referred as biofertilizers. In addition to this, biocontrol efficacy in rhizospheric region imparts strong antagonistic potential against an array of plant pathogens by secretion of various antimicrobial secondary metabolites and hydrolytic enzymes (protease, pectinase, chitinase, lipase, etc.). The biocontrol activity is exercised directly by destruction of soil-borne pathogens or indirectly by inducing plant-mediated resistance responses. Role of biocontrol agents such as Trichoderma sp., Pseudomonas fluorescens, Beauveria bassiana, and Bacillus sp. for sustainable crop production has been investigated by multi-omics approach including functional genomics, transcriptomics, proteomics, metabolomics, and secretomics. Omics-based approaches have unraveled efficient application of genetic modifications for development of various target-specific formulations. This chapter focuses on the recent biotechnological advances in biocontrol of plant pathogens for sustainable agriculture.