The novel technologies in all areas of agriculture have improved agricultural production, but some modern practices affect the environment. The recent challenge faced by advanced farming is to achieve higher yields in environment-friendly manner. Thus, there is an immediate need to find eco-friendly solutions such as wider application of biocontrol agents. Among various types of species being used as biocontrol agents, including fungi and bacteria, fungal genus Trichoderma produces different kinds of enzymes which play a major role in biocontrol activity like degradation of cell wall, tolerance to biotic or abiotic stresses, hyphal growth etc. The understanding of filamentous fungi belonging to the genus Trichoderma has continuously evolved since last two decades, from the simple concepts of biocontrol agents to their recently established role as symbionts with different beneficial effects to the plants. Recent findings from structural and functional genomics approaches suggest the additional use of these microbes as model to study mechanisms involved in multiple player interactions that is, microbes-microbes-plant-environment. In this work, historical development of Trichoderma spp., mode of action against different biological agents, potential applications and recent mass production techniques are summarized and discussed in detail with updated advances with their application in the agriculture and sustainable environment.

	Key words: Biocontrol agent, mycoparasitism, induced resistance, endophyte, mass production, bioremediation, bioreactors, agrochemicals

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Trichoderma: A significant fungus for agriculture and environment

Plant diseases are among the main constraints affecting the production and productivity of crops both in terms of quality and quantity. Use of chemicals continues to be the major tactic to mitigate the menace of crop diseases. However, because of the environmental concerns, health conscious attitude of human beings and other hazards associated with the use of chemicals, use of bio agents to suppress the disease causing activity of plant pathogens is gaining importance. The purposeful utilization of living organisms whether introduced or indigenous, other than the disease resistant host plants, to suppress the activities or populations of one or more plant pathogens is referred to as bio control. Biological control involves the use of beneficial organisms, their genes, and/or products, such as metabolites, that reduce the negative effects of plant pathogens and promote positive responses by the plant. In this direction, a number of commercial products have been registered both at national and inter-national levels based on different fungal and bacterial antagonists. These commercial products include, Biocon, Biogaurd, Ecofit, F- Stop, Soilgaurd etc with Tricoderma sp. as active ingredient, and Mycostop, Rhizoplus Subilex etc utilizing various Bacillus species as active ingredient. Biological control can achieve the objective of disease suppression through a number of ways such as antibiosis,

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Commercial Biocontrol Agents and Their Mechanism of Action in the Management of Plant Pathogens

The associations between plants and multipurpose plant growth-promoting fungi (PGPF) have been proven extremely to be beneficial to plants. This review describes new knowledge about the interactions between plants and their associated PGPF in determining improved plant growth and induced systemic resistance (ISR) to invading pathogens. It has been shown that fungi of heterogeneous classes and habitats function as PGPF. The well-known fungal genera Aspergillus, Fusarium, Penicillium, Piriformospora, Phoma, and Trichoderma are the most frequently reported PGPF. On comparing the results of different studies, it appears that plant-PGPF interactions can have positive effects on belowground and aboveground plant organs. The most commonly reported effects are significant improvement in germination, seedling vigor, biomass production, root hair development, photosynthetic efficiency, flowering, and yield. Some strains have the abilities to improve plant biochemical composition. It has now known that PGPF can also control numerous foliar and root pathogens by triggering ISR in the host plants. These capabilities are driven by their abilities to enhance nutrient uptake and phytohormone production as well as to reprogram plant gene expression, through differential activation of plant signaling pathways. The PGPF-triggered plant growth and ISR responses to pathogen attack may work through genetype-dependent manner in plants.

Plant Growth-Promoting Fungi (PGPF): Phytostimulation and Induced Systemic Resistance

Bio-protective microbial agents from rhizosphere eco-systems trigger plant defense responses provide protection against sheath blight disease in rice (Oryza sativa L.).

World population of 9.1 billion people in 2050 would require raising of overall food production by some 70% (FAO, 2009). The substantial increase in food grain production over the years has helped to meet the food security needs of the country, but the number of biotic and abiotic stress causes the yield losses up to a large extent. Biotic constraints include fungi, bacteria, virus, nematodes weeds, and insects which causes yield loss up to 31-42% (Agrios, 2005). Therefore pesticide consumption was also increases year by year as 45.39 thousand tons pesticides were consumed in the year 2012-13 (Krishijagran, 2015). Besides affecting the environment and non-target organisms, continuous and tremendous use of chemical pesticides creates high selection pressure on pathogens which force to mutation inside the pathogens and development of pesticide resistance races such as dodine and metalaxyl resistance in Venturia inequalis and Phytophthora infestans and respectively (Meszka et al., 2008, Matson et al., 2015). Pesticide resistance and environment threat due to injudicious use of chemical pesticides for disease management International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 02 (2018) Journal homepage: http://www.ijcmas.com

Review on Plant-Trichoderma-Pathogen Interaction

The efficiency of Trichoderma spp. in inducing acquired systemic disease resistance in tomato was conducted. Systemic induce resistant reaction was evaluated on chitinolytic and β-1,3glucanolytic activities produced by tomato plant (Sida cultivar) including disease severity of bacterial and gray leaf spot. Fifteen isolates of Trichoderma spp., T1, T9, T10, T13, T14, T17, T18, T19, T20, T24, T25, T30, T35, 90 and 103 were inoculated in soil of tomato potted plants. Tomato leaves were collected on 0, 5, 8, 11 and 14 days of interval after inoculation. Crude enzymes were extracted from leaf samples and determined for chitinase and β-1,3-glucanase activities. High chitinase activity was detected from Trichoderma isolates in descending order, T1, T9, T13, T18 and T18. For β-1,3-glucanase activities, The isolates T9, T13, T14 and T17 induced to tomato plant in this enzyme activity ranking from high to low, compared to uninoculated plants. Foliar disease resistant induction of Trichoderma spp. was tested under screened house condition. The Trichoderma isolate T9 (T. harzianum), T13 (T. asperellum), T17 (T. asperellum) and T18 (T. asperellum) were evaluated by cultivation in sterilized sorghum grains and inoculated in tomato pot plants. The test plants were inoculated with As. J. Food Ag-Ind. 2009, Special Issue, S99-S104 100 bacterial suspension of Xanthomonas campestris pv. vesicatoria (XCV). The result showed that T. harzianum (T9) induced resistance with the best reduction spot numbers (69.32 %.). Other isolates T13, T17 and T18 showed reduction in bacterial spot numbers of 34.66%, 37.41% and 44.77%, respectively. On Stemphylium gray leaf spot, these 4 isolates of Trichoderma spp. reduced number of spots in parenthesis as followed, T18 (19.23%), T9 (7.52%), T13 (3.8%) and T17 (3.69%). Trichoderma spp. are shown to have potential in inducing resistant of bacterial spot and gray leaf spot of tomato which varies among the range of isolates evaluated.

P. Chareerak

Papers

Induced systemic resistance of biocontrol fungus, Trichoderma spp. against bacterial and gray leaf spot in tomatoes.