Trichoderma-based products and their widespread use in agriculture

Governing bodies throughout the world, particularly in Europe, are now implementing legislative mandates with the objective of decreasing dependence on pesticides in agriculture to increase consumer and environmental safety. In order to reduce the risks associated with pesticide applications and reduce dependency on their use, Directives will promote low pesticide-input by implementing integrated pest management (IPM), and provide the means to establish the necessary conditions and measures to employ these practices, as well as to ensure security of commercial products. One approach includes the use of biological control agents and their products as alternatives to synthetic agro-chemicals. Trichoderma spp. are widely studied fungi and are among the most commonly used microbial biological control agents (MBCAs) in agriculture. They are presently marketed as bio-pesticides, biofertilizers, growth enhancers and stimulants of natural resistance. The efficacy of this fungus can be attributed to their ability to protect plants, enhance vegetative growth and contain pathogen populations under numerous agricultural conditions, as well as to act as soil amendments/inoculants for improvement of nutrient ability, decomposition and biodegradation. The living fungal spores (active substance) are incorporated in various formulations, both traditional and innovative, for applications as foliar sprays, pre-planting applications to seed or propagation material, post-pruning treatments, incorporation in the soil during seeding or transplant, watering by irrigation or applied as a root drench or dip. Trichoderma-based preparations are marketed worldwide and used for crop protection of various plant pathogens or increase the plant growth and productivity in diverse cultivated environments such as fields, greenhouses, nurseries; in the production of a variety of horticultural, fruits, trees and ornamental crops. A survey was conducted of Trichoderma-containing products found on the international market to obtain an overall perspective of the: 1) geographical distribution, 2) product composition and identity of Trichoderma species selected, 3) contents combined with Trichoderma in the products - other microbial species or substances in the mix, 4) number of products available globally and geographically, 5) number of products registered or having use specifications, 6) product formulations and applications, 7) manufacturer claims - target use, target pests, product type and effects of applications. The largest distribution of Trichoderma bioproducts is found in Asia, succeeded by Europe, South- Central America and North America. The majority of the labels indicated fungicidal properties, but only 38% of the marketed merchandise are registered. Ten Trichoderma species are specifically indicated, but many labels indicate a generic Trichoderma sp. or spp. mix in the list of ingredients. The most common formulation is a wettable powder, followed by granules. Generally, Trichoderma are applied to the seed or propagation material at the time of planting, then the secondary use is during plant development. On the whole, the target use is for the control of soilborne fungal pathogens such as Rhizoctonia, Pythium and Sclerotinia, and a few foliar pathogens such as Botrytis and Alternaria; whereas the minor use indication is for plant growth promotion. The use of Trichoderma-based biological products will have an important role in agricultural production of the future, in light of changing worldwide perspectives by consumers and governing bodies

Trichoderma and its secondary metabolites improve yield and quality of grapes

Trichoderma is one of the most studied and applied fungal biocontrol agents. The benefits of these microorganisms to the plant include: suppression of pathogens, growth promotion, enhanced nutrient availability and induction of resistance. The biological activity is related to the variety of metabolites that they produce. These metabolites have been found to directly inhibit the pathogens, increase disease resistance and enhance plant growth. In this study, we have examined the effect of two Trichoderma strains and their secondary metabolites on Vitis vinifera in terms of induction of disease resistance, plant growth promotion and increase of polyphenols or antioxidant activity in the grapes. Applications of T. harzianum M10 or T. atroviride P1, as well as their respective major secondary metabolites, harzianic acid (HA) and 6-pentyl-a-pyrone (6PP), have been conducted in greenhouse by foliar spray or drenching. The treatments suppressed the development of powdery mildew caused by Uncinula necator. In a field experiment, a spore suspension of T. harzianum strain T22 or a 6PP solution was applied until fruit harvest. The results indicated that both T. harzianum T22 and 6PP are able to improve crop yield and increase the total amount of polyphenols and antioxidant activity in the grapes. The effects of the isolated natural compounds were comparable with those obtained by using the living fungus

Application of Trichoderma harzianum, 6-pentyl-α-pyrone and Plant Biopolymer Formulations Modulate Plant Metabolism and Fruit Quality of Plum Tomatoes

Many Trichoderma are successfully used to improve agriculture productivity due to their capacity for biocontrol and to stimulate plant growth and tolerance to abiotic stress. This research elucidates the effect of applications with Trichoderma harzianum strain T22 (T22), or biopolymer (BP) alone or in combination (BP + T22 or BP + 6-pentyl-α-pyrone (6PP); a Trichoderma secondary metabolite) on the crop performance, nutritional and functional quality of greenhouse tomato (Solanum lycopersicum L. cultivar Pixel). T22 elicited significant increases in total yield (+40.1%) compared to untreated tomato. The content of lycopene, an important antioxidant compound in tomatoes, significantly increased upon treatment with T22 (+ 49%), BP + T22 (+ 40%) and BP + 6PP (+ 52%) compared to the control. T22 treatments significantly increased the content of asparagine (+37%), GABA (+87%) and MEA (+102%) over the control; whereas BP alone strongly increased GABA (+105%) and MEA (+85%). The synthesis of these compounds implies that tomato plants are able to reuse the photorespiratory amino acids and ammonium for producing useful metabolites and reduce the pressure of photorespiration on plant metabolism, thus optimizing photosynthesis and growth. Finally, these metabolites exert many beneficial effects for human health, thus enhancing the premium quality of plum tomatoes

Trichoderma secondary metabolites active on plants and fungal pathogens

Beneficial microbes typically produce bioactive molecules that can affect the interactions of plants with their pathogens. Many secondary metabolites may also have antibiotic properties, which enable the producing microbe to inhibit and/or kill other microorganisms i.e. competing for a nutritional niche. Indeed, some of these compounds have been found to play an important role in the biocontrol of plant diseases by various beneficial microbes used world-wide for crop protection and bio-fertilization. In addition to direct toxic activity against plant pathogens, biocontrol-related metabolites may also increase disease resistance by triggering systemic plant defence activity, and/or enhance root and shoot growth. Fungi belonging to the Trichoderma genus are well known producers of secondary metabolites with a direct activity against phytopathogens and compounds that substantially affect the metabolism of the plant. The widescale application of selected metabolites to induce host resistance and/or to promote crop yield may become a reality in the near future and represents a powerful tool for the implementation of IPM strategies

Multiple roles and effects of a novel Trichoderma hydrophobin

Fungi belonging to the genus Trichoderma are among the most active and ecologically successful microbes found in natural environments, as they are able to use a variety of substrates and affect the growth of other microbes and virtually any plant species. We isolated and characterized a novel type II hydrophobin secreted by the biocontrol strain MK1 of Trichoderma longibrachiatum. The corresponding gene (Hytlo1) has a multiple role in the Trichoderma-plant-pathogen three-way interaction, while the purified protein displayed a direct antifungal as well as a MAMP and a plant growth promotion (PGP) activity. Leaf infiltration with the hydrophobin systemically increased resistance to pathogens and activated defence-related responses involving ROS, SOD, oxylipins, phytoalexins and PR-proteins formation or activity. The hydrophobin was found to enhance development of a variety of plants when applied at very low doses. It particularly stimulated root formation and growth, as demonstrated also by transient expression of the encoding gene in tobacco and tomato. Targeted knock-out of Hytlo1 significantly reduced both antagonistic and PGP effect of the WT strain. We conclude that this protein represents a clear example of a molecular factor developed by Trichoderma to establish a mutually beneficial interaction with the colonized plant

Modulation of Tomato Response to Rhizoctonia solani by Trichoderma harzianum and Its Secondary Metabolite Harzianic Acid

The present study investigated the transcriptomic and metabolomic changes elicited in tomato plants (Solanum lycopersicum cv. Micro-Tom) following treatments with the biocontrol agent Trichoderma harzianum strain M10 or its purified secondary metabolite harzianic acid (HA), in the presence or the absence of the soil-borne pathogen Rhizoctonia solani. Transcriptomic analysis allowed the identification of differentially expressed genes (DEGs) that play a pivotal role in resistance to biotic stress. Overall, the results support the ability of T. harzianum M10 to activate defense responses in infected tomato plants. An induction of hormone-mediated signaling was observed, as shown by the up-regulation of genes involved in the ethylene and jasmonate (ET/JA) and salicylic acid (SA)-mediated signaling pathways. Further, the protective action of T. harzianum on the host was revealed by the over-expression of genes able to detoxify cells from reactive oxygen species (ROS). On the other hand, HA treatment also stimulated tomato response to the pathogen by inducing the expression of several genes involved in defense response (including protease inhibitors, resistance proteins like CC-NBS-LRR) and hormone interplay. The accumulation of steroidal glycoalkaloids in the plant after treatments with either T. harzianum or HA, as determined by metabolomic analysis, confirmed the complexity of the plant response to beneficial microbes, demonstrating that these microorganisms are also capable of activating the chemical defenses

Combined Biostimulant Applications of Trichoderma spp. with Fatty Acid Mixtures Improve Biocontrol Activity, Horticultural Crop Yield and Nutritional Quality

The growing demand for safer foods reflects the public perception of the adverse consequences of chemicals used in agriculture. This research aimed at developing new biological formulations based on the combination of small microbial consortia containing two Trichoderma spp., with a medium–long chain fatty acids mixture (FAm). The bioactivity of these formulations was investigated on different vegetable crops in terms of biocontrol, growth promotion, yield and quality improvements. FAm application reduced Botrytis cinerea necrosis by up to 90% compared to the infected control plants and some of the assayed Trichoderma spp. + FAm combinations contained Rhizoctonia disease, reaching more than 90% reduction of tomato and lettuce plant mortality. An increasing yield, ranging to 25 and 90%, was recorded on treated tomato, lettuce and kohlrabi compared to untreated plants. A significant enrichment in carotenoids (+60%) and glucosinolates (+39%) was measured on biotreated plants compared to controls. Untargeted LC-MS analysis revealed a higher content of tomatine and dehydro-phytosphingosine, glycoalkaloids involved in defense responses, in Trichoderma spp. + FAm combination-treated plants. The combined biostimulant applications of Trichoderma spp. with FAm were able to improve the performances of different horticultural plant species, producing a premium quality marketable vegetable with higher antioxidant content