Mycoparasitism as a mechanism of Trichoderma-mediated suppression of plant diseases

Trichoderma strain-dependent direct and indirect biocontrol of Fusarium head blight caused by Fusarium graminearum in wheat

Fusarium head blight (FHB), caused by Fusarium graminearum (Fg), is a major disease of wheat not only due to crop yield losses but also because of food safety concerns, since Fg produces toxic trichotecenes, such as deoxynivalenol (DON). Different Trichoderma strains have shown biocontrol efficacy against various Fusarium spp. in a wide variety of pathosystems. In this work, the efficacy of T. asperellum T25, T. harzianum T136 and T. simmonsii T137, was assessed against Fg ITEM 124 in in vitro tests, which included dual cultures, as well as cellulose and cellophane membrane assays. The three Trichoderma strains inhibited Fg growth to varying degrees. However, only T25 and T136 demonstrated control of FHB in wheat when applied to spikes. By quantitative real-time PCR (qPCR) we analysed the expression of eight plant defence-related marker genes in wheat spikes inoculated with Trichoderma, or not, and subsequently infected with Fg. Only wheat spikes pre-treated with T25 or T136 look to activate the salicylic acid-dependent defence, in response to pathogen infection. Expression of tri genes, involved in DON biosynthesis, was analysed by qPCR in dual-culture Trichoderma-Fg confrontations in two different media, and in the plant spikes. Confrontation results indicated that tri gene expression depends on the Trichoderma strain and the culture medium, but the three Trichoderma strains reduced the expression of tri5 in the plant. Results show that T. asperellum T25 reduced FHB disease index by more than 60 %, and was the most effective biocontrol agent, employing direct mechanisms to limit Fg growth and indirect mechanisms by priming local plant defences.

Soil Microbial Mechanisms to Improve Pear Seedling Growth by Applying Bacillus and Trichoderma-Amended Biofertilizers

Bacillus velezensis SQR9 or Trichoderma harzianum NJAU4742-amended bioorganic fertilizers might significantly improve the soil microbial community and crop yields. However, the mechanisms these microorganisms act are far away from distinctness. We combined amplicon sequencing with culturable approaches to investigate the effects of these microorganisms on pear tree growth, rhizosphere nutrients and microbial mechanisms. The SQR9 and T4742 treatments increased the total biomass of pear trees by 68% and 84%, respectively, compared to the conventional organic fertilizer treatment (CK). SQR9 tends to increase soil organic matter and available phosphorus, while T4742 more effectively enhances nitrogen, potassium, iron and zinc levels. These effects were primarily linked to changes in the microbial community. T4742 treatment enriched twice as many differential microbes as SQR9. SQR9 significantly enriched Urebacillus, Streptomyces and Mycobacterium, while T4742 increased the abundance of Pseudomonas, Aspergillus and Penicillium. In vitro experiments revealed that secondary metabolites secreted by B. velezensis SQR9 and T. harzianum NJAU4742 stimulate the growth of key probiotics associated with their respective treatments, enhancing soil fertility and plant biomass. The study revealed the specific roles of these bioorganic fertilizers in agricultural applications, providing new insights for developing effective and targeted bioorganic fertilizer products and promoting sustainable agriculture.

Co-inoculation of Trichoderma and tea root-associated bacteria enhance flavonoid production and abundance of mycorrhizal colonization in tea (Camellia sinensis)

Tea is one of the most popular nonalcoholic beverages, that contains several medicinally important flavonoids. Due to seasonal variation and various environmental stresses, the overall consistency of tea flavonoids affects the tea quality. To combat stress, plants stimulate symbiotic relationships with root-associated beneficial microbiomes that sustain nutrient allocation. Therefore, a study has been designed to understand the role of the tea root microbiome in sustaining tea leaf flavonoid production. To enumerate the microbiome, tea root and rhizoplane soil were collected from 3 years of healthy plants from Jalpaiguri district, West Bengal, India. A culture-independent approach was adopted to identify root and rhizosphere microbial diversity (BioSample: SAMN31404869; SRA: SRS15503027 [rhizosphere soil metagenome] BioSample: SAMN31404868;SRA:SRS15503030 [root metagenome]. In addition to diverse microbes, four mycorrhiza fungi, i.e., Glomus intraradices, Glomus irregulare, Paraglomus occultum and Scutellospora heterogama were predominant in collected root samples. A culture-dependent approach was also adopted to isolate several plant growth-promoting bacteria [Bacillus sp. D56, Bacillus sp. D42, Bacillus sp. DR15, Rhizobium sp. DR23 (NCBI Accession: OR821747-OR821750)] and one fungal [Trichoderma sp. AM6 (NCBI Accession:OM915414)] strain. A pot experiment was designed to assess the impact of that isolated microbiome on tea seedlings. After six months of microbiome inoculation, tea plants' physicochemical and transcriptional parameters were evaluated. The results confer that the microbiome-treated treatments [(T1-without any microbial inoculation; NCBI Accession: SAMN33591153), Trichoderma sp. AM6 (T2; NCBI Accession: SAMN33591155) and Trichoderma sp. AM6 +VAM containing tea root+synthetic microbial consortia (T5; NCBI Accession: SAMN33591154)] could enhance the total flavonoid content in tea seedlings by upregulating certain transcripts associated with the flavonoid biosynthesis pathway of tea.

The fungus Escovopsis (Ascomycota: Hypocreales): a critical review of its biology and parasitism of attine ant colonies

Two biological phenomena that contribute to increasing complexity in biological systems are mutualistic symbiotic interactions and the evolution of sociality. These two phenomena are also of fundamental importance to our understanding of the natural world. An organism that poses a threat to one or both of these is therefore also of great interest as it represents a challenge that mutualistic symbioses and social organisms have to overcome. This is the case with the fungus Escovopsis (Ascomycota: Hypocreales), which attacks the fungus garden of attine ants (Formicidae: Attina) such as the leaf cutters. This parasite has attracted much high-profile scientific interest for considerable time, and its study has been fruitful in understanding evolutionary, ecological and behavioural processes. Despite this, much of the biology and ecology of this organism remains unknown. Here we discuss this fungus and three sister genera (Escovopsioides, Luteomyces and Sympodiorosea) that until recently were considered as a single group. We first describe its position as the most highly specialised microbial symbiont in this system other than the mutualistic fungal cultivar itself and as that of greatest scientific interest. We then review the taxonomic history of the group and its macroevolution and biogeography. We examine what we know of its life cycle in the field - surprisingly little is known of how it is transmitted between colonies, but we explain what is known to date. We then review how it interacts with its host(s), first at the level of its direct interaction with the basidiomycete host fungi wherein we show the evidence for it being a mycoparasite; then at the colony level where empirical evidence points towards it being a parasite with a very low virulence or even merely a opportunist. Finally, we offer directions for future research.

Exploring the potential of Trichoderma secondary metabolites against Tetranychus urticae (Acari: Tetranychidae)

This study aimed to determine 1) the effects of fungal filtrates containing secondary metabolites from five different isolates of four different Trichoderma species (Trichoderma afroharzianum, T. guizhouense, T. harzianum, and T. virens) grown in different liquid media [malt extract broth (MEB), potato dextrose broth (PDB), yeast peptone glucose (YPG), minimal medium (MM), czapek-dox broth (CDB)] on Tetranychus urticae female, and 2) the effects of Trichoderma filtrates obtained from YPG liquid media on the different biological stages of T. urticae in Petri dish and pot experiments. Results showed that the Trichoderma filtrates produced in the YPG medium exhibited the highest mortality rate of 67.6-83.1 % against T. urticae females at 7 days post-application (dpa) compared to other media. In Petri dish experiments, the mortality rates of Trichoderma filtrates on egg, larva, protonymph and deutonymph stages of T. urticae at 7 dpa were 54.0-57.8 %, 71.5-76.0 %, 72.5-79.8 % and 72.8-80.8 %, respectively. Significant differences were observed between the Trichoderma species and control (P < 0.01) but not among the Trichoderma species (P > 0.05). Trichoderma afroharzianum (83 %) and T. virens (84 %) showed the highest mortality rate on T. urticae adult females at 7 dpa and statistically significant differences were observed among Trichoderma species. Pot experiments revealed that the number of viable T. urticae eggs and mobile stages was significantly lower for T. afroharzianum (110.3 eggs, 105.8 mobile stages) and T. virens (118.5 eggs, 115.3 mobile stages) compared to the control (518.9 eggs, 452.5 mobile stages) at 7 dpa. Significant differences were observed between Trichoderma species and control, but not between T. afroharzianum and T. virens. These findings suggest that Trichoderma secondary metabolites are highly effective against economically important pest such as T. urticae, demonstrating their potential as bio-acaricides. Future research should focus on identifying the specific acaricidal compound(s) within these filtrates.

From glycans to green biotechnology: exploring cell wall dynamics and phytobiota impact in plant glycopathology

Filamentous plant pathogens, including fungi and oomycetes, pose significant threats to cultivated crops, impacting agricultural productivity, quality and sustainability. Traditionally, disease control heavily relied on fungicides, but concerns about their negative impacts motivated stakeholders and government agencies to seek alternative solutions. Biocontrol agents (BCAs) have been developed as promising alternatives to minimize fungicide use. However, BCAs often exhibit inconsistent performances, undermining their efficacy as plant protection alternatives. The eukaryotic cell wall of plants and filamentous pathogens contributes significantly to their interaction with the environment and competitors. This highly adaptable and modular carbohydrate armor serves as the primary interface for communication, and the intricate interplay within this compartment is often mediated by carbohydrate-active enzymes (CAZymes) responsible for cell wall degradation and remodeling. These processes play a crucial role in the pathogenesis of plant diseases and contribute significantly to establishing both beneficial and detrimental microbiota. This review explores the interplay between cell wall dynamics and glycan interactions in the phytobiome scenario, providing holistic insights for efficiently exploiting microbial traits potentially involved in plant disease mitigation. Within this framework, the incorporation of glycobiology-related functional traits into the resident phytobiome can significantly enhance the plant's resilience to biotic stresses. Therefore, in the rational engineering of future beneficial consortia, it is imperative to recognize and leverage the understanding of cell wall interactions and the role of the glycome as an essential tool for the effective management of plant diseases.

Screening of Antagonistic Trichoderma Strains to Enhance Soybean Growth

This study investigates the isolation and screening of Trichoderma strains that exhibit antagonistic properties against soybean root-infecting Fusarium species, particularly F. oxysporum. From soybean rhizosphere soil, 37 antagonistic Trichoderma strains were identified using the plate confrontation method, demonstrating inhibitory effects ranging from 47.57% to 72.86% against F. oxysporum. Strain 235T4 exhibited the highest inhibition rate at 72.86%. Molecular identification confirmed that the strains belonged to eight species within the Trichoderma genus, with notable strains promoting soybean growth in greenhouse tests. In pot experiments, the application of Trichoderma significantly reduced the disease index of soybean plants inoculated with F. oxysporum, particularly with strain 223H16, which achieved an 83.78% control efficiency. Field applications further indicated enhanced soybean growth metrics, including increased pod numbers and plant height, when treated with specific Trichoderma strains. Additionally, Trichoderma application enriched the fungal diversity in the soybean rhizosphere, resulting in a significant reduction of Fusarium populations by approximately 50%. This study highlights the potential of Trichoderma species as biological control agents to enhance soybean health and productivity while improving soil fungal diversity.

Effective control of snake fruit (Salacca zalacca) rot using Trichoderma asperelloides SKRU-01: A safe approach to preserving fruit quality

Rot disease, caused by the fungal pathogen Peniophora salaccae SKRU002, affects the quality of snake fruit production. In the pursuit of sustainable disease management, biocontrol using Trichoderma asperelloides SKRU-01 offers a promising solution. This study evaluated the antagonistic potential of T. asperelloides SKRU-01 against P. salaccae SKRU002 in both in vitro assays and snake fruit trials, while also assessing its impact on fruit quality. In vitro dual culture assays revealed that T. asperelloides SKRU-01 inhibited P. salaccae SKRU002 growth by 62.5 % over 10 days through efficient nutrient colonization. Microscopic analysis confirmed that T. asperelloides SKRU-01 hyphae penetrated and wrapped around P. salaccae SKRU002, causing cytoplasmic lysis. Additionally, T. asperelloides SKRU-01 culture filtrates (20 % v/v) completely inhibited P. salaccae SKRU002 growth in both solid and liquid media. LC-QTOF/MS analysis identified 31 secondary metabolites, including toyocamycin and antimycin A1. In snake fruit trials, T. asperelloides SKRU-01 culture filtrates provided 100 % protection against disease incidence (DI) and severity (DS), comparable to Mancozeb®. The application of T. asperelloides SKRU-01 spores (107 spores/mL) reduced DI and DS to 0 % within 1-3 days post-pathogen inoculation, demonstrating both protective and curative effects. Furthermore, while P. salaccae SKRU002 significantly affected fruit quality-causing weight loss, color changes, and reductions in total soluble solids, phenolic content, titratable acidity, and antioxidant activity-the simultaneous application of T. asperelloides SKRU-01 mitigated these effects without compromising fruit quality. These findings indicate the antagonistic activity of T. asperelloides SKRU-01 and its metabolites against P. salaccae SKRU002, suggesting their potential as biofungicidal agents for managing rot disease in snake fruit.

Co-inoculation of Trichoderma viride with Azospirillum brasilense could suppress the development of Harpophora maydis-infected maize in Egypt

Plant diseases caused by fungal pathogens are responsible for severe damage to strategic crops worldwide. Late wilt disease (LWD) is a vascular disease that occurs late in maize development. Harpophora maydis, the causative agent of maize LWD, is responsible for significant economic losses in Egypt. Therefore, the aim of this study was to control LWD of maize using an alternative approach to reduce the use of chemical pesticides. A combination of Trichoderma viride, a fungal biocontrol agent, and Azospirillum brasilense, a bacterial endophytic plant growth promoter, was applied in vitro and in planta. T. viride showed high mycoparasitic potential against H. maydis via various antagonistic activities, including the production of lytic enzymes, secondary metabolites, volatile compounds, and siderophores. A. brasilense and T. viride filtrates were also shown to suppress H. maydis growth, in addition to their ability to produce gibberellic and indole acetic acids. A significant change in the metabolites secreted by T. viride was observed using GC/MS in the presence of H. maydis. A field experiment was conducted on susceptible and resistant hybrids of maize to evaluate the antagonistic activity of T. viride combined with A. brasilense on LWD incidence as well as plant growth promotion under field conditions. The data revealed a significant decrease in both disease incidence and severity in maize plants treated with T. viride and/or A. brasilense. Further, there was a noticeable increase in all plant growth and yield parameters. An anatomical examination of the control and inoculated maize roots was also reflective of plant responses under biotic stress. Taken together, the obtained results provide successful eco-friendly management strategies against LWD in maize.

Talaromyces purpureogenus CEF642N as a Promising Biocontrol Agent for Cotton Disease Control

Endophytic fungi live in healthy plant tissues and organs and are a major source of natural bioactive compounds. In this study, we found that an endophytic fungus, Talaromyces purpureogenus CEF642N, isolated from the healthy cotton roots, suppressed Verticillium dahliae by up to 53% after 15 days in a confrontation culture. Genome sequencing of CEF642N and mass spectrometry study of its metabolites were used to identify its primary antagonists. To further elucidate the antagonistic mechanism, transcriptome analysis and ultrastructure observation of the pathogen were performed. The antagonists were shown to act on the mitochondria and cell membranes of the pathogen. In addition, CEF642N also had mycoparasitic effects on V. dahliae. These results suggest that CEF642N has the potential to be an important biocontrol agent for efficiently managing Verticillium wilt, a severe disease affecting cotton.

Trichoderma brevicompactum 6311: Prevention and Control of Phytophthora capsici and Its Growth-Promoting Effect

Pepper Phytophthora blight caused by Phytophthora capsici results in substantial losses in global pepper cultivation. The use of biocontrol agents with the dual functions of disease suppression and crop growth promotion is a green and sustainable way of managing this pathogen. In this study, six biocontrol strains of Trichoderma with high antagonistic activity against P. capsici were isolated and screened from the rhizosphere soil of healthy peppers undergoing long-term continuous cultivation. Morphological identification and molecular biological identification revealed that strains 2213 and 2221 were T. harzianum, strains 5111, 6311, and 6321 were T. brevicompactum, and strain 7111 was T. virens. The results showed that T. brevicompactum 6311 had the greatest inhibitory effect against P. capsici. The inhibition rate of 6311 on the mycelial growth of P. capsici was 82.22% in a double-culture test, whereas it reached 100% in a fermentation liquid culture test. Meanwhile, the pepper fruit tests showed that 6311 was 29% effective against P. capsici on pepper, and a potting test demonstrated that the preventive and controlling effect of 6311 on pepper epidemics triggered by P. capsici was 55.56%. The growth-promoting effect, germination potential, germination rate, radicle-embryonic axis length, germination index, and fresh weight of peppers cultured in the 6311 fermentation broth were significantly increased compared with the results for the control group. Scanning electron microscopy revealed that 6311 achieved the parasitism of P. capsici, producing siderophores and the growth hormone indoleacetic acid (IAA) to achieve disease-suppressive and growth-promoting functions. Transcriptomic results indicated that genes encoding proteins involved in plant disease resistance, namely flavanone 3-hydroxylase (F3H) and growth transcription factor (AUX22), were generally upregulated after the application of 6311. This study demonstrated that 6311 exhibits significant bioprotective and growth-promoting functions.

Biological control of bacterial leaf blight (BLB) in rice-A sustainable approach

Bacterial leaf blight (BLB) in rice, caused by the pathogen Xanthomonas oryzae pv. oryzae, is a significant agricultural problem managed through chemical control and cultivating rice varieties with inherent resistance to the bacterial pathogen. Research has highlighted the potential of using antagonistic microbes which can suppress the BLB pathogen through the production of secondary metabolites like siderophores, rhamnolipids, and hydroxy-alkylquinolines offering a sustainable alternative for BLB management. Additionally, the induction of plant immunity and defense-related enzymes in rice further enhances the resistance against the disease. Therefore, implementation of biological controls can complement chemical treatments in contributing towards the sustainability of rice production systems by aiming at host immunity improvement and killing of pathogen. It is crucial to continue exploring and understanding the complex interactions between various beneficial microbes, the rice plants, and the BLB pathogen to optimize and implement effective biocontrol strategies in future.

Lessons from the field: Trichoderma in agriculture and human health

The use of Trichoderma in agriculture as both a biocontrol agent and biofertilizer hinges on its ability to colonize the rhizosphere, promote plant growth, endure adverse environments, compete for space and nutrients, and produce enzymes and secondary metabolites to mycoparasitize and infect other fungus. In humans, Trichoderma exhibits the capacity to infect various bodily tissues, leading to Trichodermosis. There has been a notable increase in cases ranging from superficial to fatal, invasive, and disseminated infections, particularly among immunocompromised individuals. Trichoderma species employ diverse strategies to colonize and survive in various environments, infecting phytopathogens; however, the mechanisms and virulence factors contributing to human infections remain poorly understood. In this mini review, we provide a brief overview and contextualization of the virulence mechanisms employed by Trichoderma in parasitizing other fungi, as well as those implicated in modulating plant immunity and inducing human infections. Furthermore, we discuss the similarity of these virulence factors capable of modulating the mammalian immune system and their potential implications for human infection.

Light Regulates Secreted Metabolite Production and Antagonistic Activity in Trichoderma

Secondary metabolism is one of the main mechanisms Trichoderma uses to explore and colonize new niches, and 6-pentyl-α-pyrone (6-PP) is an important secondary metabolite in this process. This work focused on standardizing a method to investigate the production of 6-PP. Ethanol and ethyl acetate were both effective solvents for quantifying 6-PP in solution and had limited solubility in potato-dextrose-broth media. The 6-PP extraction using ethyl acetate provided a rapid and efficient process to recover this metabolite. The 6-PP was readily produced during the development of Trichoderma atroviride growing in the dark, but light suppressed its production. The 6-PP was purified, and its spectrum by nuclear magnetic resonance and mass spectroscopy was identical to that of commercial 6-PP. Light also induced or suppressed other unidentified metabolites in several other species of Trichoderma. The antagonistic activity of T. atroviride was influenced by light, as suppression of plant pathogens was greater in the dark. The secreted metabolite production on potato-dextrose-agar was differentially regulated by light, indicating that Trichoderma produced several metabolites with antagonistic activity against plant pathogens. Light has an important influence on the secondary metabolism and antagonistic activity of Trichoderma, and this trait is of key relevance for selecting antagonistic Trichoderma strains for plant protection.

Effects of Two Trichoderma Strains on Apple Replant Disease Suppression and Plant Growth Stimulation

Fusarium oxysporum, the pathogen responsible for apple replant disease (ARD), is seriously threatening the apple industry globally. We investigated the antagonistic properties of Trichoderma strains against F. oxysporum HS2, aiming to find a biological control solution to minimize the dependence on chemical pesticides. Two of the thirty-one Trichoderma strains assessed through plate confrontation assays, L7 (Trichoderma atroviride) and M19 (T. longibrachiatum), markedly inhibited = F. oxysporum, with inhibition rates of 86.02% and 86.72%, respectively. Applying 1 × 106 spores/mL suspensions of these strains notably increased the disease resistance in embryonic mung bean roots. Strains L7 and M19 substantially protected Malus robusta Rehd apple rootstock from ARD; the plant height, stem diameter, leaf number, chlorophyll content, and defense enzyme activity were higher in the treated plants than in the controls in both greenhouse and field trials. The results of fluorescent labeling confirmed the effective colonization of these strains of the root soil, with the number of spores stabilizing over time. At 56 days after inoculation, the M19 and L7 spore counts in various soils confirmed their persistence. These results underscore the biocontrol potential of L7 and M19 against HS2, offering valuable insights into developing sustainable ARD management practices.

Isolation and Characterization of Biocontrol Microbes for Development of Effective Microbial Consortia for Managing Rhizoctonia bataticola Root Rot of Cluster Bean Under Hot Arid Climatic Conditions

Development of native microbial consortia is crucial for the sustainable management of plant diseases in modern agriculture. This study aimed to evaluate the antagonistic potential of various microbial isolates against Rhizoctonia bataticola, a significant soil-borne pathogen. A total of 480 bacteria, 283 fungi, and 150 actinomycetes were isolated and screened using in vitro dual plate assays. Among these, isolates 5F, 131B, 223B, and 236B demonstrated the highest antagonistic activity, with inhibition rates of 88.24%, 87.5%, 81.25%, and 81.25%, respectively. The selected isolates were further assessed for abiotic stress tolerance, revealing their ability to thrive under extreme conditions. Characterization of biocontrol and plant growth-promoting activities revealed the production of siderophores, hydrogen cyanide, ammonia, chitinase, and indole-3-acetic acid, along with the solubilization of zinc and phosphorus. Compatibility tests confirmed the potential of forming effective microbial consortia, which significantly reduced the percent disease index in cluster bean. The most effective consortium, comprising Trichoderma afroharzianum 5F, Pseudomonas fluorescens 131B, Bacillus licheniformis 223B, and Bacillus subtilis 236B, achieved a 76.5% disease control. Additionally, this consortium enhanced total phenol (92.1%), flavonoids (141.6%), and antioxidant defense enzyme activities including POX (188.5%), PPOX (116.3%), PAL (71.2%), and TAL (129.9%) in cluster bean plants over the infected control, leading to substantial improvements in systemic resistance of plants. This consortium also significantly enhanced plant height, fresh weight, dry weight, number of pods per plant, and seed yield over the infected control as well as mock control. This study underscores the potential of these robust microbial consortia as a sustainable and effective strategy for managing R. bataticola and enhancing crop productivity under extreme environmental conditions.

Polyphasic Characterization of the Biocontrol Potential of a Novel Strain of Trichoderma atroviride Isolated from Central Mexico

This work describes the characterization of Trichoderma atroviride strain CMU-08, isolated from Michoacán, Mexico. CMU-08 demonstrated robust growth and conidiation across a temperature range from 16 to 32 °C and a pH range from 4 to 9 on potato dextrose agar (PDA) and malt extract agar (MEA) media. The strain is an efficient antagonist of six species of phytopathogenic fungi and oomycetes in PDA, MEA, and Vogel minimal medium (VMM). Antagonist mechanisms of CMU-08 included direct mycoparasitism observed in dual-culture assays, as well as antibiosis attributed to growth inhibition via both volatile and non-volatile metabolites, with the effectiveness varying depending on the test phytopathogen and culture medium. Extracellular filtrates (ECFs) recovered from liquid cultures of CMU-08 under basal and induced conditions using Botrytis cinerea cell walls significantly inhibited their growth at a concentration of 750 µg/mL. Moreover, in detached tomato leaf assays, these ECFs reduced foliar damage caused by B. cinerea by 24-34%. The volatile organic compounds (VOCs) produced by CMU-08 also exhibited substantial efficacy, reducing foliar damage by up to 50% in similar tests. Despite showing no basal extracellular chitinase enzymatic activity, CMU-08 demonstrated significant induction of this activity in cultures supplemented with B. cinerea and Fusarium sp. cell walls. Four genes encoding extracellular chitinases (chit33, chit36, ech42, and locus 217415) showed different dynamics of transcriptional regulation during the dual-culture confrontation of strain CMU-08 with B. cinerea and Fusarium sp., varying according to the phytopathogen and the interaction stage. The CMU-08 strain shows physiological versatility and employs a variety of antagonist mechanisms toward different species of phytopathogenic microorganisms, making it a good candidate for developing a biocontrol product for field application.

Volatile Organic Compounds Produced by Co-Culture of Burkholderia vietnamiensis B418 with Trichoderma harzianum T11-W Exhibits Improved Antagonistic Activities against Fungal Phytopathogens

Recently, there has been a growing interest in the biocontrol activity of volatile organic compounds (VOCs) produced by microorganisms. This study specifically focuses on the effects of VOCs produced by the co-culture of Burkholderia vietnamiensis B418 and Trichoderma harzianum T11-W for the control of two phytopathogenic fungi, Botrytis cinerea and Fusarium oxysporum f. sp. cucumerium Owen. The antagonistic activity of VOCs released in mono- and co-culture modes was evaluated by inhibition assays on a Petri dish and in detached fruit experiments, with the co-culture demonstrating significantly higher inhibitory effects on the phytopathogens on both the plates and fruits compared with the mono-cultures. Metabolomic profiles of VOCs were conducted using the solid-liquid microextraction technique, revealing 341 compounds with significant changes in their production during the co-culture. Among these compounds, linalool, dimethyl trisulfide, dimethyl disulfide, geranylacetone, 2-phenylethanol, and acetophenone were identified as having strong antagonistic activity through a standard inhibition assay. These key compounds were found to be related to the improved inhibitory effect of the B418 and T11-W co-culture. Overall, the results suggest that VOCs produced by the co-culture of B. vietnamiensis B418 and T. harzianum T11-W possess great potential in biological control.

Accumulation of pathogens in soil microbiome can explain long-term fluctuations of legumes in a grassland community

All plant populations fluctuate in time. Apart from the dynamics imposed by external forces such as climate, these fluctuations can be driven by endogenous processes taking place within the community. In this study, we aimed to identify potential role of soil-borne microbial communities in driving endogenous fluctuations of plant populations. We combined a unique, 35-yr long abundance data of 11 common plant species from a species-rich mountain meadow with development of their soil microbiome (pathogenic fungi, arbuscular mycorrhizal fungi and oomycetes) observed during 4 yr of experimental cultivation in monocultures. Plant species which abundance fluctuated highly in the field (particularly legumes) accumulated plant pathogens in their soil mycobiome. We also identified increasing proportion of mycoparasitic fungi under highly fluctuating legume species, which may indicate an adaptation of these species to mitigate the detrimental effects of pathogens. Our study documented that long-term fluctuations in the abundance of plant species in grassland communities can be explained by the accumulation of plant pathogens in plant-soil microbiome. By contrast, we found little evidence of the role of mutualists in plant population fluctuations. These findings offer new insights for understanding mechanisms driving both long-term vegetation dynamics and patterns of species coexistence and richness.

Antifungal Activity and Possible Mechanism of Streptomyces nojiriensis 9-13 Against Mycogone sp., Causing Wet Bubble Disease on Agaricus bisporus

Wet bubble disease (WBD) in Agaricus bisporus caused by Mycogone species imposes a substantial economic loss to mushroom production in China. Currently, fungicide application is the main method to control WBD. However, excessive use of fungicides is challenged by the appearance of resistance and food safety. Therefore, it is necessary to explore safe and efficient strategies to control WBD. Strain 9-13, isolated from the rhizosphere soil of Taxus chinensis, showed strong inhibitory activity against three Mycogone species. According to morphological and biochemical characteristics and multilocus phylogenetic analysis, the strain was identified as Streptomyces nojiriensis. In addition, strain 9-13 extracts significantly inhibited mycelial growth and spore germination of M. perniciosa, M. rosea, and M. xinjiangensis in vitro. Strain 9-13 and its extracts also exhibited broad-spectrum antifungal activities against 12 selected plant pathogenic fungi. Scanning electron microscopic observations showed that the extracts destroyed mycelial structure, inducing mycelia to twist and shrink. Moreover, transmission electron microscopy revealed that the extracts resulted in severe plasmolysis, rupture of the cell membrane, and a decrease in cell inclusions, and the cell wall had a rough and uneven surface. Notably, the extracts obviously reduced disease severity and incidence of WBD by from 83.85 to 87.32% in fruiting bodies and 77.36% in mushroom beds and maintained fruiting time and color on harvested mushrooms. Collectively, these results clearly indicate that S. nojiriensis 9-13 is a promising biocontrol agent to control WBD on A. bisporus.

Carbon and Nitrogen Sources Influence Parasitic Responsiveness in Trichoderma atroviride NI-1

Parasitic species of Trichoderma use hydrolytic enzymes to destroy the host cell wall. Preferent carbon and nitrogen sources suppress the expression of genes related to parasitism. Here, different nutrients were evaluated in the parasitic isolated NI-1, which was identified as Trichoderma atroviride. The genes cbh1 and chb2 (cellobiohydrolases), bgl3.1 (endoglucanase), and pra1 and prb1 (proteinases) were poorly expressed during the interaction between NI-1 and Phytophthora capsici on PDA. However, gene expression improved on minimal medium with preferent and alternative carbon sources. Dextrin and glucose stimulated higher transcript levels than cellulose, sucrose, and glycerol. Also, ammonium stimulated a stronger parasitic responsiveness than the alternative nitrogen sources. During interaction against different phytopathogens, NI-1 detects their host differentially from a distance due to the cbh1 and cbh2 genes being only induced by P. capsici. The pra1 and ech42 genes were induced before contact with Botrytis cinerea and Rhizoctonia solani, while when confronted with P. capsici they were stimulated until contact and overgrowth. The prb1 and bgl3.1 genes were induced before contact against the three-host assayed. Overall, T. atroviride prefers to parasitize and has the capacity to distinguish between an oomycete and a fungus, but nutrient quality regulates its parasitic responsiveness.

Efficacy of Trichoderma spp. and Kosakonia sp. Both Independently and Combined with Fungicides against Botrytis cinerea on Strawberries

Background: The ascomycete Botrytis cinerea is a major pathogen of strawberry, often causing grey mold and significant yield losses. Its management has largely relied on chemical fungicides, which, while effective, can lead to resistant pathogens and harm to non-target organisms and pose health risks. Objectives: This study explored a strategy for minimizing chemical usage by combining biocontrol agents (BCAs) with half-strength fungicide input. Results: In vitro results of fungicide-amended culture plates indicated that the presence of 625 µg mL-1 Azoxystrobin exhibited no growth inhibition of T. atroviride T19 and T. harzianum T16 but increased conidial density of T16 by 90%. Copper (750 µg mL-1) did not suppress the growth of T. virens TVSC or T16 but rather promoted it by 9.5% and 6%, respectively. Additionally, copper increased T16 sporulation by 1.4-fold. Greenhouse trials demonstrated that combining T23 with half-strength Azoxystrobin was as effective as the full dosage in suppressing flower rot. Among the antagonists assessed, Kosakonia sp. exhibited the lowest incidence of fruit rot, whereas T23 resulted in a moderate incidence. Moreover, the combination of T16 or Kosakonia sp. with half-strength copper was almost as effective as the full dosage in reducing fruit rot. Conclusions: Our findings suggest integrating these BCAs in the sustainable management of grey mold in strawberries.

Genus-wide analysis of Trichoderma antagonism toward Pythium and Globisporangium plant pathogens and the contribution of cellulases to the antagonism

Parasitism is an important lifestyle in the Trichoderma genus but has not been studied in a genus-wide way toward Pythium and Globisporangium hosts. Our approach screened a genus-wide set of 30 Trichoderma species in dual culture assays with two soil-borne Pythium and three Globisporangium plant-parasitic species and used exo-proteomic analyses, with the aim to correlate Trichoderma antagonism with potential strategies for attacking Pythium and Globisporangium. The Trichoderma spp. showed a wide range of antagonism from strong to weak, but the same Trichoderma strain showed similar levels toward all the Pythium and Globisporangium species. The Trichoderma enzymes from strong (Trichoderma asperellum, Trichoderma atroviride, and Trichoderma virens), moderate (Trichoderma cf. guizhouense and Trichoderma reesei), and weak (Trichoderma parepimyces) antagonists were induced by the autoclaved mycelia of one of the screened Pythium species, Pythium myriotylum. The variable proportions of putative cellulases, proteases, and redox enzymes suggested diverse as well as shared strategies amongst the antagonists. There was a partial positive correlation between antagonism from microscopy and the cellulase activity induced by autoclaved P. myriotylum mycelia in different Trichoderma species. The deletion of the cellulase transcriptional activator XYR1 in T. reesei led to lower antagonism toward Pythium and Globisporangium. The antagonism of Pythium and Globisporangium appears to be a generic property of Trichoderma as most of the Trichoderma species were at least moderately antagonistic. While a role for cellulases in the antagonism was uncovered, cellulases did not appear to make a major contribution to T. reesei antagonism, and other factors are also likely contributing.IMPORTANCETrichoderma is an important genus widely distributed in nature with broad ecological impacts and applications in the biocontrol of plant diseases. The Pythium and Globisporangium genera of fungus-like water molds include many important soil-borne plant pathogens that cause various diseases. Most of the Trichoderma species showed at least a moderate ability to compete with or antagonize the Pythium and Globisporangium hosts, and microscopy showed examples of parasitism (a slow type of killing) and predation (a fast type of killing). Hydrolytic enzymes such as cellulases and proteases produced by Trichoderma likely contribute to the antagonism. A mutant deficient in cellulase activity had reduced antagonism. Interestingly, Pythium and Globisporangium species contain cellulose in their cell walls (unlike true fungi such as Trichoderma), and the cellulolytic ability of Trichoderma appears beneficial for antagonism of water molds.

Neg1 overexpression in Trichoderma harzianum T4 enhanced its ability to produce spores and antagonistic activity against phytopathogenic fungi

Trichoderma harzianum T4 is a soil fungus that plays an important role in the biological control of plant diseases. The aim of this study was to functionally characterize the β-1,6-glucanase gene Neg1 in T. harzianum T4 and to investigate the effect of its overexpression on biocontrol traits, especially antagonism against pathogenic fungi. We found that overexpression of Neg1 did not affect growth of T. harzianum but enhanced sporulation of T. harzianum T4 cultures. Generally, spores are closely related to the defense ability of defense fungi and can assist their proliferation and improve their colonization ability. Secondly, overexpression of Neg1 also increased the secretion level of various hydrolytic enzymes and enhanced the antagonistic ability against phytopathogenic fungi of Fusarium spp. The results suggest that Neg1 is a key gene for improving the biocontrol effect of T. harzianum T4, which contributes to a better understanding of the mechanism of action of T. harzianum T4 as a fungal biocontrol agent.

An insight into pathogenicity and virulence gene content of Xanthomonas spp. and its biocontrol strategies

The genus Xanthomonas primarily serves as a plant pathogen, targeting a diverse range of economically significant crops on a global scale. Xanthomonas spp. utilizes a collection of toxins, adhesins, and protein effectors as part of their toolkit to thrive in their surroundings, and establish themselves within plant hosts. The bacterial secretion systems (Type 1 to Type 6) assist in delivering the effector proteins to their intended destinations. These secretion systems are specialized multi-protein complexes responsible for transporting proteins into the extracellular milieu or directly into host cells. The potent virulence and systematic infection system result in rapid dissemination of the bacteria, posing significant challenges in management due to complexities and substantial loss incurred. Consequently, there has been a notable increase in the utilization of chemical pesticides, leading to bioaccumulation and raising concerns about adverse health effects. Biological control mechanisms through beneficial microorganism (Bacillus, Pseudomonas, Trichoderma, Burkholderia, AMF, etc.) have proven to be an appropriate alternative in integrative pest management system. This review details the pathogenicity and virulence factors of Xanthomonas, as well as its control strategies. It also encourages the use of biological control agents, which promotes sustainable and environmentally friendly agricultural practices.

Potential application of a fungal co-culture crude extract for the conservation of post-harvest fruits

Fungal plant pathogens are responsible for serious losses in many economically important crop species worldwide. Due to the use of fungicides and the fungi genome plasticity, multi-drug resistant strains are emerging as a new generation of pathogens, causing an expansive range of superficial and systemic plant infections, or new opportunistic fungal pathogens for humans. The group of antagonistic fungi Trichoderma spp. has been widely used to enhance plant growth and for the control of different pathogens affecting crops. Although Neurospora crassa is not a mycoparasitic fungus, its secretion of secondary metabolites with antimicrobial activity has been described. In this work, the effect of crude extract of the monoculture of Trichoderma asperellum T8a or the co-culture with N. crassa as an inhibitory treatment against the fungal pathogens Botrytis cinerea and Fusarium solani was evaluated. The findings demonstrate that the secondary metabolites contained in the T. asperellum crude extract have a clear fungistatic activity against B. cinerea and F. solani. Interestingly, this fungistatic activity highly increases when T. asperellum is co-cultivated with the non-pathogenic fungus N. crassa. Moreover, the co-culture crude extract also showed antifungal activity on post-harvest fruits, and no toxic effects on Murine fibroblast L929 (CCL-1) and murine macrophages RAW 264.7 (TIB-71) were observed. All these results together are solid evidence of the potential of the co-culture crude extract of T. asperellum and N. crassa, as an antifungal agent against phytopathogenic fungi, or post-harvest fruits during the transportation or commercialization time.

Trichoderma carraovejensis: a new species from vineyard ecosystem with biocontrol abilities against grapevine trunk disease pathogens and ecological adaptation

Trichoderma strains used in vineyards for the control of grapevine trunk diseases (GTDs) present a promising alternative to chemical products. Therefore, the isolation and characterization of new indigenous Trichoderma strains for these purposes is a valuable strategy to favor the adaptation of these strains to the environment, thus improving their efficacy in the field. In this research, a new Trichoderma species, Trichoderma carraovejensis, isolated from vineyards in Ribera de Duero (Spain) area, has been identified and phylogenetically analyzed using 20 housekeeping genes isolated from the genome of 24 Trichoderma species. A morphological description and comparison of the new species has also been carried out. In order to corroborate the potential of T. carraovejensis as a biological control agent (BCA), confrontation tests against pathogenic fungi, causing various GTDs, have been performed in the laboratory. The compatibility of T. carraovejensis with different pesticides and biostimulants has also been assessed. This new Trichoderma species demonstrates the ability to control pathogens such as Diplodia seriata, as well as high compatibility with powdered sulfur-based pesticides. In conclusion, the autochthonous species T. carraovejensis can be an effective alternative to complement the currently used strategies for the control of wood diseases in its region of origin.

Allochthonous Trichoderma Isolates Boost Atractylodes lancea Herb Quality at the Cost of Rhizome Growth

Atractylodes lancea is a perennial herb whose rhizome (AR) is a valuable traditional Chinese medicine with immense market demand. The cultivation of Atractylodes lancea faces outbreaks of root rot and deterioration in herb quality due to complex causes. Here, we investigated the effects of Trichoderma spp., well-known biocontrol agents and plant-growth-promoters, on ARs. We isolated Trichoderma strains from healthy ARs collected in different habitats and selected three T. harzianum strains (Th2, Th3 and Th4) with the strongest antagonizing effects on root rot pathogens (Fusarium spp.). We inoculated geo-authentic A. lancea plantlets with Th2, Th3 and Th4 and measured the biomass and quality of 70-day-old ARs. Th2 and Th3 promoted root rot resistance of A. lancea. Th2, Th3 and Th4 all boosted AR quality: the concentration of the four major medicinal compounds in ARs (atractylon, atractylodin, hinesol and β-eudesmol) each increased 1.6- to 18.2-fold. Meanwhile, however, the yield of ARs decreased by 0.58- to 0.27-fold. Overall, Th3 dramatically increased the quality of ARs at a relatively low cost, namely lower yield, showing great potential for practical application. Our results showed selectivity between A. lancea and allochthonous Trichoderma isolates, indicating the importance of selecting specific microbial patches for herb cultivation.

Extracellular vesicles from the mycoparasitic fungus Trichoderma harzianum

Trichoderma harzianum is a filamentous fungus that can act as a mycoparasite, saprophyte, or a plant symbiotic. It is widely used as a biological control agent against phytopathogenic fungi and can also be used for plant growth promotion and biofortification. Interaction between T. harzianum and phytopathogenic fungi involves mycoparasitism, competition, and antibiosis. Extracellular vesicles (EVs) have been described as presenting a central role in mechanisms of communication and interaction among fungus and their hosts. In this study, we characterized extracellular vesicles of T. harzianum produced during growth in the presence of glucose or S. sclerotiorum mycelia. A set of vesicular proteins was identified using proteomic approach, mainly presenting predicted signal peptides.

Molecular Insights into Plant-Microbe Interactions: A Comprehensive Review of Key Mechanisms

In most ecosystems, plants establish complex symbiotic relationships with organisms, such as bacteria and fungi, which significantly influence their health by promoting or inhibiting growth. These relationships involve biochemical exchanges at the cellular level that affect plant physiology and have evolutionary implications, such as species diversification, horizontal gene transfer, symbiosis and mutualism, environmental adaptation, and positive impacts on community structure and biodiversity. For these reasons, contemporary research, moving beyond observational studies, seeks to elucidate the molecular basis of these interactions; however, gaps in knowledge remain. This is particularly noticeable in understanding how plants distinguish between beneficial and antagonistic microorganisms. In light of the above, this literature review aims to address some of these gaps by exploring the key mechanisms in common interspecies relationships. Thus, our study presents novel insights into these evolutionary archetypes, focusing on the antibiosis process and microbial signaling, including chemotaxis and quorum sensing. Additionally, it examined the biochemical basis of endophytism, pre-mRNA splicing, and transcriptional plasticity, highlighting the roles of transcription factors and epigenetic regulation in the functions of the interacting organisms. These findings emphasize the importance of understanding these confluences in natural environments, which are crucial for future theoretical and practical applications, such as improving plant nutrition, protecting against pathogens, developing transgenic crops, sustainable agriculture, and researching disease mechanisms. It was concluded that because of the characteristics of the various biomolecules involved in these biological interactions, there are interconnected molecular networks in nature that give rise to different ecological scaffolds. These networks integrate a myriad of functionally organic units that belong to various kingdoms. This interweaving underscores the complexity and multidisciplinary integration required to understand plant-microbe interactions at the molecular level. Regarding the limitations inherent in this study, it is recognized that researchers face significant obstacles. These include technical difficulties in experimentation and fieldwork, as well as the arduous task of consolidating and summarizing findings for academic articles. Challenges range from understanding complex ecological and molecular dynamics to unbiased and objective interpretation of diverse and ever-changing literature.

Genome and transcriptome sequencing of Trichoderma harzianum T4, an important biocontrol fungus of Rhizoctonia solani, reveals genes related to mycoparasitism

Trichoderma harzianum is a well-known biological control strain and a mycoparasite of Rhizoctonia solani. To explore the mechanisms of mycoparasitism, the genome and transcriptome of T. harzianum T4 were both assembled and analyzed in this study. The genome of T. harzianum T4 was assembled into 106 scaffolds, sized 41.25 Mb, and annotated with a total of 8118 predicted genes. We analyzed the transcriptome of T. harzianum T4 against R. solani in a dual culture in three culture periods: before contact (BC), during contact (C), and after contact (AC). Transcriptome sequencing identified 1092, 1222, and 2046 differentially expressed genes (DEGs), respectively. These DEGs, which are involved in pathogen recognition and signal transduction, hydrolase, transporters, antibiosis, and defense-related functional genes, are significantly upregulated in the mycoparasitism process. The results of genome and transcriptome analysis indicated that the mycoparasitism process of T. harzianum T4 was very complex. T. harzianum successfully recognizes and invades host cells and kills plant pathogens by regulating various DEGs at different culture periods. The relative expression levels of the 26 upregulated DEGs were confirmed by RT-qPCR to validate the reliability of the transcriptome data. The results provide insight into the molecular mechanisms underlying T. harzianum T4's mycoparasitic processes, and they provide a potential molecular target for the biological control mechanism of T. harzianum T4.

Hydrogel capsules as new delivery system for Trichoderma koningiopsis Th003 to control Rhizoctonia solani in rice (Oryza sativa)

The incorporation of biological control agents (BCAs) such as Trichoderma spp. in agricultural systems favors the transition towards sustainable practices of plant nutrition and diseases control. Novel bioproducts for crop management are called to guarantee sustainable antagonism activity of BCAs and increase the acceptance of the farmers. The encapsulation in polymeric matrices play a prominent role for providing an effective carrier/protector and long-lasting bioproduct. This research aimed to study the influence of biopolymer in hydrogel capsules on survival and shelf-life of T. koningiopsis. Thus, two hydrogel capsules prototypes based on alginate (P1) and amidated pectin (P2), containing conidia of T. koningiopsis Th003 were formulated. Capsules were prepared by the ionic gelation method and calcium gluconate as crosslinker. Conidia releasing under different pH values of the medium, survival of conidia in drying capsules, storage stability, and biocontrol activity against rice sheath blight (Rhizoctonia solani) were studied. P2 prototype provided up to 98% survival to Th003 in fluid bed drying, faster conidia releasing at pH 5.8, storage stability greater than 6 months at 18 °C, and up to 67% of disease reduction. However, both biopolymers facilitate the antagonistic activity against R. solani, and therefore can be incorporated in novel hydrogel capsules-based biopreparations. This work incites to develop novel biopesticides-based formulations with potential to improve the delivery process in the target site and the protection of the active ingredient from the environmental factors.

Biocontrol of Diplodia bulgarica, the causal agent of apple canker, using Trichoderma zelobreve

Apple (Malus domestica Borkh) is one of the most consumed and nutritious fruits. Iran is one of the main producers of the apple in the world. Diplodia bulgarica is the major causal agent of apple tree decline in Iran. Biological control is a nature-friendly approach to plant disease management. Trichoderma zelobreve was isolated from apple trees infected with Diplodia bulgarica in West Azarbaijan province of Iran. The results showed that T. zelobreve strongly inhibited the colony growth of D. bulgarica. In vivo assay on detached branches of apple tree cv. Golden Delicious using T. zelobreve mycelial plug showed that canker length/stem length (CL/SL) and canker perimeter/stem perimeter (CP/SP) indices decreased by 76 and 69%, respectively, 21 days after inoculation. Additionally, wettable powder formulation (WPF) containing the antagonistic fungus "T. zelobreve" decreased CL and CP/SP by 75 and 67%, respectively, 6 months after inoculation. Moreover, canker progress curves and the area under the disease progress curve (AUDPC) supported these findings. The growth temperatures of the antagonist and pathogen were similar, indicating the adaptation of T. zelobreve for biocontrol of apple canker caused by D. bulgarica. The results also showed that T. zelobreve-based WPF stored at 25 °C assure excellent shelf life at least 4 months, allowing the bioproduct to be stored at room temperature, which is a great advantage and cost-effective option.

Trunk Injection Delivery of Biocontrol Strains of Trichoderma spp. Effectively Suppresses Nut Rot by Gnomoniopsis castaneae in Chestnut (Castanea sativa Mill.)

Gnomoniopsis castaneae is responsible for brown or chalky nut rot in sweet chestnut (Castanea sativa), causing heavy reductions in nut production. Controlling it is challenging, due to its inconspicuous infections, erratic colonization of host tissues and endophytic lifestyle. Fungicides are not applicable because they are prohibited in chestnut forests and strongly discouraged in fruit chestnut groves. Trichoderma species are safe and wide-spectrum biocontrol agents (BCAs), with a variety of beneficial effects in plant protection. This study tested selected strains of T. viride, T. harzianum and T. atroviride for their ability to suppress G. castaneae. Field experiments were conducted in four chestnut groves (two test plots plus two controls) at two sites with a different microclimate. As the size of the trees were a major drawback for uniform and effective treatments, the Trichoderma strains were delivered directly by trunk injection, using the BITE® (Blade for Infusion in TrEes) endotherapic tool. The BCA application, repeated twice in two subsequent years, significantly reduced nut rot incidence, with a more marked, presumably cumulative, effect in the second year. Our data showed the tested Trichoderma strains retain great potential for the biological control of G. castaneae in chestnut groves. The exploitation of Trichoderma spp. as biopesticides is a novelty in the forestry sector and proves the benefits of these microbes in plant disease protection.

Trichoderma Inoculation Alleviates Cd and Pb-Induced Toxicity and Improves Growth and Physiology of Vigna radiata (L.)

Heavy metals (HMs) pose a serious threat to agricultural productivity. Therefore, there is a need to find sustainable approaches to combat HM stressors in agriculture. In this study, we isolated Trichoderma sp. TF-13 from metal-polluted rhizospheric soil, which has the ability to resist 1600 and 1200 μg mL-1 cadmium (Cd) and lead (Pb), respectively. Owing to its remarkable metal tolerance, this fungal strain was applied for bioremediation of HMs in Vigna radiata (L.). Strain TF-13 produced siderophore, salicylic acid (SA; 43.4 μg mL-1) and 2,3-DHBA (21.0 μg mL-1), indole-3-acetic acid, ammonia, and ACC deaminase under HM stressed conditions. Increasing concentrations of tested HM ions caused severe reduction in overall growth of plants; however, Trichoderma sp. TF-13 inoculation significantly (p ≤ 0.05) increased the growth and physiological traits of HM-treated V. radiata. Interestingly, Trichoderma sp. TF-13 improved germination rate (10%), root length (26%), root biomass (32%), and vigor index (12%) of V. radiata grown under 25 μg Cd kg-1 soil. Additionally, Trichoderma inoculation showed a significant (p ≤ 0.05) increase in total chlorophyll, chl a, chl b, carotenoid content, root nitrogen (N), and root phosphorus (P) of 100 μg Cd kg-1 soil-treated plants over uninoculated treatment. Furthermore, enzymatic and nonenzymatic antioxidant activities of Trichoderma inoculated in metal-treated plants were improved. For instance, strain TF-13 increased proline (37%), lipid peroxidation (56%), catalase (35%), peroxidase (42%), superoxide dismutase (27%), and glutathione reductase (39%) activities in 100 μg Pb kg-1 soil-treated plants. The uptake of Pb and Cd in root/shoot tissues was decreased by 34/39 and 47/38% in fungal-inoculated and 25 μg kg-1 soil-treated plants. Thus, this study demonstrates that stabilizing metal mobility in the rhizosphere through Trichoderma inoculation significantly reduced the detrimental effects of Cd and Pb toxicity in V. radiata and also enhanced development under HM stress conditions.

Bioprotective yeasts: Potential to limit postharvest spoilage and to extend shelf life or improve microbial safety of processed foods

Yeasts are a widespread group of microorganisms that are receiving increasing attention from scientists and industry. Their diverse biological activities and broad-spectrum antifungal activity make them promising candidates for application, especially in postharvest biocontrol of fruits and vegetables and food biopreservation. The present review focuses on recent knowledge of the mechanisms by which yeasts inhibit pathogenic fungi and/or spoilage fungi and bacteria. The main mechanisms of action of bioprotective yeasts include competition for nutrients and space, synthesis and secretion of antibacterial compounds, mycoparasitism and the secretion of lytic enzymes, biofilm formation, quorum sensing, induced systemic resistance of fruit host, as well as the production of reactive oxygen species. Preadaptation of yeasts to abiotic stresses such as cold acclimatization and sublethal oxidative stress can improve the effectiveness of antagonistic yeasts and thus more effectively play biocontrol roles under a wider range of environmental conditions, thereby reducing economic losses. Combined application with other antimicrobial substances can effectively improve the efficacy of yeasts as biocontrol agents. Yeasts show great potential as substitute for chemical additives in various food fields, but their commercialization is still limited. Hence, additional investigation is required to explore the prospective advancements of yeasts in the field of biopreservation for food.

Endophytic fungi: Unravelling plant-endophyte interaction and the multifaceted role of fungal endophytes in stress amelioration

Endophytic fungi colonize interior plant tissue and mostly form mutualistic associations with their host plant. Plant-endophyte interaction is a complex mechanism and is currently a focus of research to understand the underlying mechanism of endophyte asymptomatic colonization, the process of evading plant immune response, modulation of gene expression, and establishment of a balanced mutualistic relationship. Fungal endophytes rely on plant hosts for nutrients, shelter, and transmission and improve the host plant's tolerance against biotic stresses, including -herbivores, nematodes, bacterial, fungal, viral, nematode, and other phytopathogens. Endophytic fungi have been reported to improve plant health by reducing and eradicating the harmful effect of phytopathogens through competition for space or nutrients, mycoparasitism, and through direct or indirect defense systems by producing secondary metabolites as well as by induced systemic resistance (ISR). Additionally, for efficient crop improvement, practicing them would be a fruitful step for a sustainable approach. This review article summarizes the current research progress in plant-endophyte interaction and the fungal endophyte mechanism to overcome host defense responses, their subsequent colonization, and the establishment of a balanced mutualistic interaction with host plants. This review also highlighted the potential of fungal endophytes in the amelioration of biotic stress. We have also discussed the relevance of various bioactive compounds possessing antimicrobial potential against a variety of agricultural pathogens. Furthermore, endophyte-mediated ISR is also emphasized.

Identification of mycoparasitism-related genes in Trichoderma harzianum T4 that are active against Colletotrichum musae

Trichoderma harzianum is a well-known biological control agent (BCA) that shows great potential in controlling many pathogenic fungi. To screen for genes associated with mycoparasitism, we sequenced and analyzed the transcriptome of T. harzianum T4 grown in dual culture with Colletotrichum musae. We analyzed differentially expressed genes (DEGs) of Trichoderma harzianum T4 in three different culture periods: before contact (BC), during contact (C) and after contact (AC). A total of 1453 genes were significantly differentially expressed compared to when T. harzianum T4 was cultured alone. During the three periods of double culture of T. harzianum T4 with C. musae, 74, 516, and 548 genes were up-regulated, respectively, and 11, 315, and 216 genes were down-regulated, respectively. The DEGs were screened using GO and KEGG enrichment analyses combined with differential expression multiples. Six gene categories related to mycoparasitism were screened: (a) pathogen recognition and signal transduction, (b) hydrolases, (c) ribosomal proteins and secreted proteins, (d) multidrug-resistant proteins and transporters, (e) heat shock proteins and detoxification, and (f) oxidative stress and antibiotics-related genes. The expression levels of 24 up-regulated genes during T. harzianum T4's antagonistic interaction with C. musae were detected via real-time fluorescence quantitative PCR (RT-qPCR). This study provided information on the transcriptional expression of T. harzianum T4 against C. musae. These results may help us to further understand the mechanism of mycoparasitism, which can provide a potential molecular target for improving the biological control capacity of T. harzianum T4.

Identification and Characterization of Peptaibols as the Causing Agents of Pseudodiploöspora longispora Infecting the Edible Mushroom Morchella

Pseudodiploöspora longispora (previously known as Diploöspora longispora) is a pathogenic fungus of Morchella mushrooms. The molecular mechanism underlying the infection of P. longispora in fruiting bodies remains unknown. In this study, three known peptaibols, alamethicin F-50, polysporin B, and septocylindrin B (1-3), and a new analogue, longisporin A (4), were detected and identified in the culture of P. longispora and the fruiting bodies of M. sextelata infected by P. longispora. The primary amino sequence of longisporin A is defined as Ac-Aib1-Pro2-Aib3-Ala4-Aib5-Aib6-Gln7-Aib8-Val9-Aib10-Glu11-Leu12-Aib13-Pro14-Val15-Aib16-Aib17-Gln18-Gln19-Phaol20. The peptaibols 1-4 greatly suppressed the mycelial growth of M. sextelata. In addition, treatment with alamethicin F-50 produced damage on the cell wall and membrane of M. sextelata. Compounds 1-4 also exhibited inhibitory activities against human pathogens including Aspergillus fumigatus, Candida albicans, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus, and plant pathogen Verticillium dahlia. Herein, peptaibols are confirmed as virulence factors involved in the invasion of P. longispora on Morchella, providing insights into the interaction between pathogenic P. longispora and mushrooms.

Accumulation of Health-Promoting Compounds in Upland Black Rice by Interacting Mycorrhizal and Endophytic Fungi

There is an increasing interest in finding eco-friendly and safe approaches to increase agricultural productivity and deliver healthy foods. Arbuscular mycorrhizal fungi (AMF) and endophytic fungi (EPF) are important components of sustainable agriculture in view of their ability to increase productivity and various plant secondary metabolites with health-promoting effects. In a pot experiment, our main research question was to evaluate the additive and synergistic effects of an AMF and four root-endophytic fungi on plant performance and on the accumulation of health-promoting secondary compounds. Plant growth varied between the treatments with both single inoculants and co-inoculation of an AMF and four EPF strains. We found that inoculation with a single EPF positively affected the growth and biomass production of most of the plant-endophyte consortia examined. The introduction of AMF into this experiment (dual inoculation) had a beneficial effect on plant growth and yield. AMF, Rhizophagus variabilis KS-02 co-inoculated with EPF, Trichoderma zelobreve PBMP16 increased the highest biomass, exceeding the growth rate of non-inoculated plants. Co-inoculated R. variabilis KS-02 and T. zelobreve PBMP16 had significantly greater beneficial effects on almost all aspects of plant growth, photosynthesis-related parameters, and yield. It also promoted root growth quality and plant nutrient uptake. The phenolic compounds, anthocyanin, and antioxidant capacity in rice seeds harvested from plants co-inoculated with AMF and EPF were dramatically increased compared with those from non-inoculated plants. In conclusion, our results indicated that EPF and AMF contributed to symbiosis in Maled Phai cultivar and were coordinately involved in promoting plant growth performance under a pot trial.

Mycorrhizas and Trichoderma fungi increase the accumulation of secondary metabolites in grain legume leaves and suppress foliar diseases in field-grown conditions of the humid forest of Cameroon

BACKGROUND

Arbuscular mycorrhizal and Trichoderma fungi alter the synthesis of secondary metabolites of plants and confer tolerance from pathogens attacks. However, there is less supportive evidence from on-field studies confirming the above-mentioned hypothesis, particularly for the humid forest zone of Cameroon where pathogens are important sources of yield losses for legumes such as soybean and common bean.

MATERIALS AND METHODS

We evaluated the impacts of mycorrhiza isolates of Rhizophagus intraradices (Ri) and Trichoderma asperellum (Ta) fungi and their co-inoculations (Ta x Ri) in the synthetizing of leaves secondary metabolites, foliar disease symptoms, growth, N and P uptake, and yields of three genotypes of soybean (TGx 1485-1D, TGx 1990-93 F, and TGx 1990-97 F) and common beans (NUA-99, DOR-701, and PNN) under field conditions of Cameroon.

RESULTS

We found that common bean plants showed a lower foliar infection rate but a higher increase in root colonization intensity, shoot dry weight, and N and P uptakes than soybeans when inoculated with Ri and Ta treatment. However, the grain yield of soybean soybean was higher (2000 kg ha 1) than the common bean plants for the Ri × Ta treatment. The soybean genotype TGx 1990-93F had increased root colonization intensity and the lowest foliar infection rate, making it stronger and tolerant to pathogen attacks when co-inoculated with Ri × Ta fungi (F). Bean plants inoculated with Ri and the co-inoculated with Ri × Ta demonstrated lower symptoms of foliar attack, and increased root colonization, particularly the PNN variety. The total amino acid and proline accumulations were higher for soybean than common bean plants due to fungi inoculations, and soybean genotypes accumulated more excellent contents of amino acid and proline in the control (10.1 mg g- 1 fwt) that significantly increased under the Ri × Ta inoculation (13.4 mg g- 1 fwt).

CONCLUSIONS

Common bean plants inoculated with Ta and Ri fungi accumulated higher phenolic compounds in their leaves that aided them in overcoming the pathogen attacks than soybean plants.

Potential of Trichoderma virens HZA14 in Controlling Verticillium Wilt Disease of Eggplant and Analysis of Its Genes Responsible for Microsclerotial Degradation

Verticillium dahliae is a soilborne fungal pathogen that causes vascular wilt diseases in a wide range of economically important crops, including eggplant. Trichoderma spp. are effective biological control agents that suppress a wide range of plant pathogens through a variety of mechanisms, including mycoparasitism. However, the molecular mechanisms of mycoparasitism of Trichoderma spp. in the degradation of microsclerotia of V. dahliae are not yet fully understood. In this study, the ability of 15 isolates of Trichoderma to degrade microsclerotia of V. dahliae was evaluated using a dual culture method. After 15 days, isolate HZA14 showed the greatest potential for microsclerotial degradation. The culture filtrate of isolate HZA14 also significantly inhibited the mycelial growth and conidia germination of V. dahliae at different dilutions. Moreover, this study showed that T. virens produced siderophores and indole-3-acetic acid (IAA). In disease control tests, T. virens HZA14 reduced disease severity in eggplant seedlings by up to 2.77%, resulting in a control efficacy of 96.59% at 30 days after inoculation. Additionally, inoculation with an HZA14 isolate increased stem and root length and fresh and dry weight, demonstrating plant growth promotion efficacy. To further investigate the mycoparasitism mechanism of T. virens HZA14, transcriptomics sequencing and real-time fluorescence quantitative PCR (RT-qPCR) were used to identify the differentially expressed genes (DEGs) of T. virens HZA14 at 3, 6, 9, 12, and 15 days of the interaction with microsclerotia of V. dahliae. In contrast to the control group, the mycoparasitic process of T. virens HZA14 exhibited differential gene expression, with 1197, 1758, 1936, and 1914 genes being up-regulated and 1191, 1963, 2050, and 2114 genes being down-regulated, respectively. Among these genes, enzymes associated with the degradation of microsclerotia, such as endochitinase A1, endochitinase 3, endo-1,3-beta-glucanase, alpha-N-acetylglucosaminidase, laccase-1, and peroxidase were predicted based on bioinformatics analysis. The RT-qPCR results confirmed the RNA-sequencing data, showing that the expression trend of the genes was consistent. These results provide important information for understanding molecular mechanisms of microsclerotial degradation and integrated management of Verticillium wilt in eggplant and other crops.

Pathogenic invasive microbes Trichoderma pleuroticola transform bacterial and fungal community diversity in Auricularia cornea crop production system

Pathogenic invasion of Trichoderma pleuroticola profoundly altered microflora in the Auricularia cornea crop production system, impacting diversity and composition in both artificial bed-log and fruiting bodies. A more complex ecological network between the diseased and healthy bodies. Researchers still have poor knowledge about how the important agricultural relationship between the composition of the microbiome of the artificial bed-log and the fruiting bodies is infected by the pathogenic invasive microbes T. pleuroticola, but this knowledge is crucial if we want to use or improve it. Here, we investigated 8 groups (48 biological samples) across 5 growth stages of the A. cornea production system using metagenomic technology. Diseased and healthy fruiting bodies exhibited distinct microbial compositions, while core members in artificial bed-logs remained stable. Core microbiota analysis highlighted Pseudomonas and Pandoraea bacterial genera, as well as Sarocladium, Cephalotrichum, Aspergillus, and Mortierella fungal genera as biomarker species after the bodies were treated with the pathogenic invasive microbes T. pleuroticola. In diseased bodies, these core members upregulated pathways including polymyxin resistance, L-arginine degradation II, superpathway of L-arginine and L-ornithine degradation, glucose degradation (oxidative), glucose and glucose-1-phosphate degradation, promoting fruit spoilage. Our data confirm that T. pleuroticola plays an important role in the early stages of disease development in the A. cornea crop generation system. The exposed volatile core microbiome may play an important role in accelerating T. pleuroticola-induced decay of fruiting bodies.

Transboundary milRNAs: Indispensable molecules in the process of Trichoderma breve T069 mycoparasitism of Botrytis cinerea

Despite the increasing number of fungal microRNA-like small RNAs (milRNAs) being identified and reported, profiling of milRNAs in biocontrol fungi and their roles in the mycoparasitism of pathogenic fungi remains limited. Therefore, in this study, we constructed a GFP fluorescence strain to evaluate the critical period of mycoparasitism in the interaction system between T. breve T069 and B. cinerea. The results showed that the early stage of Trichoderma mycoparasitism occurred 12 h after hyphal contact and was characterized by hyphal parallelism, whereas the middle stage lasted 36 h was characterized by wrapping. The late stage of mycoparasitism occurred at 72 h was characterized by the degradation of B. cinerea mycelia. We subsequently identified the sRNAs of T. breve T069 and B. cinerea during the critical period of mycoparasitism using high-throughput sequencing. In ltR1, 45 potential milRNA targets were identified for 243 genes, and 73 milRNAs targeted 733 genes in ltR3. Additionally, to identify potential transboundary miRNAs in T. breve T069, we screened for miRNAs that were exclusively expressed and had precursor structures in the T. breve T069 genome but were absent in the B. cinerea genome. Next, we predicted the target genes of B. cinerea. Our findings showed that 14 potential transboundary milRNAs from T. breve T069 targeted 41 genes in B. cinerea. Notably, cme-MIR164a-p5_1ss17CT can target 15 genes, including Rim15 (BCIN_15g00280), Nop53 (BCIN_12g03770), Skn7 (BCIN_02g08650), and Vel3 (BCIN_03g06410), while ppe-MIR477b-p3_1ss11TC targeted polyketide synthase (BCIN_03g04360, PKS3). The target gene of PC-5p-27397_41 was a non-ribosomal peptide synthetase (BCIN_01g03730, Bcnrps6). PC-3p-0029 (Tri-milR29) targeted chitin synthetase 7. These genes play crucial roles in normal mycelial growth and pathogenicity of B. cinerea. In conclusion, this study highlights the significance of milRNAs in Trichoderma mycoparasitism of B. cinerea. This discovery provides a new strategy for the application of miRNAs in the prevention and treatment of fungal pathogens.

Trichoderma hamatum and Its Benefits

Trichoderma hamatum (Bonord.) Bainier (T. hamatum) belongs to Hypocreaceae family, Trichoderma genus. Trichoderma spp. are prominently known for their biocontrol activities and plant growth promotion. Hence, T. hamatum also possess several beneficial activities, such as antimicrobial activity, antioxidant activity, insecticidal activity, herbicidal activity, and plant growth promotion; in addition, it holds several other beneficial properties, such as resistance to dichlorodiphenyltrichloroethane (DDT) and degradation of DDT by certain enzymes and production of certain polysaccharide-degrading enzymes. Hence, the current review discusses the beneficial properties of T. hamatum and describes the gaps that need to be further considered in future studies, such as T. hamatum's potentiality against human pathogens and, in contrast, its role as an opportunistic human pathogen. Moreover, there is a need for substantial study on its antiviral and antioxidant activities.

Trichoderma agriamazonicum sp. nov. (Hypocreaceae), a new ally in the control of phytopathogens

The genus Trichoderma comprises more than 500 valid species and is commonly used in agriculture for the control of plant diseases. In the present study, a Trichoderma species isolated from Scleronema micranthum (Malvaceae) has been extensively characterized and the morphological and phylogenetic data support the proposition of a new fungal species herein named Trichoderma agriamazonicum. This species inhibited the mycelial growth of all the nine phytopathogens tested both by mycoparasitism and by the production of VOCs, with a highlight for the inhibition of Corynespora cassiicola and Colletotrichum spp. The VOCs produced by T. agriamazonicum were able to control Capsicum chinense fruit rot caused by Colletotrichum scovillei and no symptoms were observed after seven days of phytopathogen inoculation. GC-MS revealed the production of mainly 6-amyl-α-pyrone, 1-octen-3-ol and 3-octanone during interaction with C. scovillei in C. chinense fruit. The HLPC-MS/MS analysis allowed us to annotate trikoningin KBII, hypocrenone C, 5-hydroxy-de-O-methyllasiodiplodin and unprecedented 7-mer peptaibols and lipopeptaibols. Comparative genomic analysis of five related Trichoderma species reveals a high number of proteins shared only with T. koningiopsis, mainly the enzymes related to oxidative stress. Regarding the CAZyme composition, T. agriamazonicum is most closely related to T. atroviride. A high protein copy number related to lignin and chitin degradation is observed for all Trichoderma spp. analyzed, while the presence of licheninase GH12 was observed only in T. agriamazonicum. Genome mining analysis identified 33 biosynthetic gene clusters (BGCs) of which 27 are new or uncharacterized, and the main BGCs are related to the production of polyketides. These results demonstrate the potential of this newly described species for agriculture and biotechnology.

Structures and Biological Activities of Secondary Metabolites from the Trichoderma genus (Covering 2018-2022)

Trichoderma, a genus with more than 400 species, has a long history of use as an industrial bioreactor, biofertilizer, and biocontrol agent. It is considered a significant source of secondary metabolites (SMs) that possess unique structural features and a wide range of bioactivities. In recent years, numerous secondary metabolites of Trichoderma, including terpenoids, polyketides, peptides, alkaloids, and steroids, have been identified. Most of these SMs displayed antimicrobial, cytotoxic, and antifungal effects. This review focuses on the structural diversity, biological activities, and structure-activity relationships (SARs) of the SMs isolated from Trichoderma covered from 2018 to 2022. This study provides insights into the exploration and utilization of bioactive compounds from Trichoderma species in the agriculture or pharmaceutical industry.

Trichoderma as a biological control agent: mechanisms of action, benefits for crops and development of formulations

Currently, the food and economic losses generated by the attack of phytopathogens on the agricultural sector constitute a severe problem. Conventional crop protection techniques based on the application of synthetic pesticides to combat these undesirable microorganisms have also begun to represent an inconvenience since the excessive use of these substances is associated with contamination problems and severe damage to the health of farmers, consumers, and communities surrounding the fields, as well as the generation of resistance by the phytopathogens to be combated. Using biocontrol agents such as Trichoderma to mitigate the attack of phytopathogens represents an alternative to synthetic pesticides, safe for health and the environment. This work explains the mechanisms of action through which Trichoderma exerts biological control, some of the beneficial aspects that it confers to the development of crops through its symbiotic interaction with plants, and the bioremedial effects that it presents in fields contaminated by synthetic pesticides. Also, detail the production of spore-based biopesticides through fermentation processes and formulation development.

Effect of Metarhizium anisopliae (MetA1) on growth enhancement and antioxidative defense mechanism against Rhizoctonia root rot in okra

Rhizoctonia solani is an important necrotrophic pathogenic fungus that causes okra root disease and results in severe yield reduction. Many biocontrol agents are being studied with the intent of improving plant growth and defense systems and reducing crop loss by preventing fungal infections. Recently, a member of the Hypocrealean family, Metarhizium anisopliae, has been reported for insect pathogenicity, endophytism, plant growth promotion, and antifungal potentialities. This research investigated the role of M. anisopliae (MetA1) in growth promotion and root disease suppression in okra. The antagonism against R. solani and the plant growth promotion traits of MetA1 were tested in vitro. The effects of endophytic MetA1 on promoting plant growth and disease suppression were assessed in planta. Dual culture and cell-free culture filtrate assays showed antagonistic activity against R. solani by MetA1. Some plant growth promotion traits, such as phosphate solubilization and catalase activity were also exhibited by MetA1. Seed primed with MetA1 increased the shoot, root, leaves, chlorophyll content, and biomass content compared to control okra plants. The plants challenged with R. solani showed the highest hydrogen peroxide (H2O2) and lipid peroxidation (MDA) contents in the leaves of okra. Whereas MetA1 applied plants showed a reduction of H2O2 and MDA by 5.21 and 14.96%, respectively, under pathogen-inoculated conditions by increasing antioxidant enzyme activities, including catalase (CAT), peroxidase (POD), glutathione S-transferase (GST), and ascorbate peroxidase (APX), by 30.11, 10.19, 5.62, and 5.06%, respectively. Moreover, MetA1 increased soluble sugars, carbohydrates, proline, and secondary metabolites, viz., phenol and flavonoid contents in okra resulting in a better osmotic adjustment of diseases infecting plants. MetA1 reduced disease incidence by 58.33% at 15 DAI compared to the R. solani inoculated plant. The results revealed that MetA1 improved plant growth, elevated the plant defense system, and suppressed root diseases caused by R. solani. Thus, MetA1 was found to be an effective candidate for the biological control program.

Light-Induced Changes in Secondary Metabolite Production of Trichoderma atroviride

Many studies aim at maximizing fungal secondary metabolite production but the influence of light during cultivation has often been neglected. Here, we combined an untargeted isotope-assisted liquid chromatography-high-resolution mass spectrometry-based metabolomics approach with standardized cultivation of Trichoderma atroviride under three defined light regimes (darkness (PD), reduced light (RL) exposure, and 12/12 h light/dark cycle (LD)) to systematically determine the effect of light on secondary metabolite production. Comparative analyses revealed a similar metabolite profile upon cultivation in PD and RL, whereas LD treatment had an inhibiting effect on both the number and abundance of metabolites. Additionally, the spatial distribution of the detected metabolites for PD and RL was analyzed. From the more than 500 detected metabolites, only 25 were exclusively produced upon fungal growth in darkness and 85 were significantly more abundant in darkness. The majority were detected under both cultivation conditions and annotation revealed a cluster of substances whose production followed the pattern observed for the well-known T. atroviride metabolite 6-pentyl-alpha-pyrone. We conclude that cultivation of T. atroviride under RL can be used to maximize secondary metabolite production.