The diversity of anti-microbial secondary metabolites produced by fungal endophytes: an interdisciplinary perspective

Survey of potential fungal antagonists of Coffee Leaf Rust (Hemileia vastatrix) on Coffea arabica in Hawai'i, USA

Hemileia vastatrix, causal agent of coffee leaf rust (CLR), is an aggressive pathogen of coffee plants worldwide. Conventional fungicides play a major role in the suppression of this disease, but a recent shift toward eco-friendly farming practices has occurred and additional novel, effective, and sustainable strategies for CLR control are needed. Naturally occurring fungal antagonists could be well-positioned to meet this demand, but these fungi need to be isolated and tested for efficacy to identify organisms with potential. In this study, a survey of fungi associated with CLR lesions in four districts of Hawai'i Island, HI, USA (Kona, Ka'ū, Hāmākua, and Hilo) was conducted. Coffee leaves infected with CLR were collected from 22 locations and over 600 lesions were plated on ½ APDA and CTC 4T media. DNA was extracted from purified isolates and the internal transcribed spacer region (ITS) was sequenced and analyzed by BLASTn. In total, 194 isolates comprising 50 taxa were recovered. Several of the genera are known antagonists of CLR or other plant pathogens, including Simplicillium, Akanthomyces, Cladosporium, Fusarium, and Clonostachys. The wide diversity of fungi associated with CLR lesions provide a wealth of possibilities for identifying potential CLR antagonists that could serve as a valuable tool for coffee farmers as part of an integrated pest management plan.

A derivative of trihydroxynaphthalenone and a pyrone metabolite from the endophytic fungus Talaromyces purpurpgenus

A newly discovered trihydroxynaphthalenone derivative, epoxynaphthalenone (1) involving the condensation of ortho-hydroxyl groups into an epoxy structure, and a novel pyrone metabolite characterized as pyroneaceacid (2), were extracted from Talaromyces purpurpgenus, an endophytic fungus residing in Rhododendron molle. The structures of these compounds were elucidated through a comprehensive analysis of their NMR and HRESIMS data. The determination of absolute configurations was accomplished using electronic circular dichroism (ECD) calculations and CD spectra. Notably, these recently identified metabolites exhibited a moderate inhibitory activity against xanthine oxidase (XOD).

Uncovering the antifungal activities of wild apple-associated bacteria against two canker-causing fungi, Cytospora mali and C. parasitica

Cytospora canker has become a devastating disease of apple species worldwide, and in severe cases, it may cause dieback of entire trees. The aim of this study was to characterize the diversity of cultivable bacteria from the wild apple microbiota and to determine their antifungal ability against the canker-causing pathogenic fungi Cytospora mali and C. parasitica. Five bacterial strains belonging to the species Bacillus amyloliquefaciens, B. atrophaeus, B. methylotrophicus, B. mojavensis, and Pseudomonas synxantha showed strong antagonistic effects against pathogenic fungi. Therefore, since the abovementioned Bacillus species produce known antifungal compounds, we characterized the antifungal compounds produced by Ps. synxantha. Bacteria grown on nutritional liquid medium were dehydrated, and the active compound from the crude extract was isolated and analysed via a range of chromatographic processes. High-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance analyses revealed a bioactive antifungal compound, phenazine-1-carboxylic acid (PCA). The minimum inhibitory concentration (MIC) demonstrated that PCA inhibited mycelial growth, with a MIC of 10 mg mL-1. The results suggested that PCA could be used as a potential compound to control C. mali and C. malicola, and it is a potential alternative for postharvest control of canker disease.

A review on endophytic fungi: a potent reservoir of bioactive metabolites with special emphasis on blight disease management

Phytopathogenic microorganisms have caused blight diseases that present significant challenges to global agriculture. These diseases result in substantial crop losses and have a significant economic impact. Due to the limitations of conventional chemical treatments in effectively and sustainably managing these diseases, there is an increasing interest in exploring alternative and environmentally friendly approaches for disease control. Using endophytic fungi as biocontrol agents has become a promising strategy in recent years. Endophytic fungi live inside plant tissues, forming mutually beneficial relationships, and have been discovered to produce a wide range of bioactive metabolites. These metabolites demonstrate significant potential for fighting blight diseases and provide a plentiful source of new biopesticides. In this review, we delve into the potential of endophytic fungi as a means of biocontrol against blight diseases. We specifically highlight their significance as a source of biologically active compounds. The review explores different mechanisms used by endophytic fungi to suppress phytopathogens. These mechanisms include competing for nutrients, producing antifungal compounds, and triggering plant defense responses. Furthermore, this review discusses the challenges of using endophytic fungi as biocontrol agents in commercial applications. It emphasizes the importance of conducting thorough research to enhance their effectiveness and stability in real-world environments. Therefore, bioactive metabolites from endophytic fungi have considerable potential for sustainable and eco-friendly blight disease control. Additional research on endophytes and their metabolites will promote biotechnology solutions.

Biosynthesis of resveratrol by an endophytic Priestia megaterium PH3 via the phenylpropane pathway

Resveratrol (RES) is a secondary metabolite synthesized by plants in response to environmental stress and pathogen infection, which is of great significance for the industrial production of RES by fermentation culture. In this study, we aimed to explore the biosynthesis pathway of RES and its key enzymes in the Priestia megaterium PH3, which was isolated and screened from peanut fruit. Through Liquid Chromatography-Mass Spectrometry (LC-MS) analysis, we quantified the RES content and distribution in the culture medium and determined that Priestia megaterium PH3 mainly secreted RES extracellularly. Furthermore, the highest production of RES was observed in YPD, yielding an impressive 127.46 ± 6.11 μg/L. By optimizing the fermentation conditions, we achieved a remarkable RES yield of 946.82 ± 24.74 μg/L within just 2 days, which represents the highest reported yield for a natural isolate produced in such a short time frame. Our investigation revealed that the phenylpropane pathway is responsible for RES synthesis in this bacterium, with cinnamate 4-hydroxylase (C4H) identified as the main rate-limiting enzyme. Overall, our findings highlight the robust RES production capabilities of Priestia megaterium PH3, offering novel insights and potential applications for bacterial fermentation in RES production. KEY POINTS: • RES synthesized by the bacterium was confirmed through the phenylpropane pathway. • The key rate-limiting enzyme for biosynthesis-RES is C4H. • RES reached 946.82 ± 24.74 μg/L after fermentation for 2 days.

New steroid produced by Periconia pseudobyssoides K5 isolated from Toona sureni (Meliaceae) and its heme polymerization inhibition activity

A new ergostane-type steroid named (22E)-3α,6α,9α-ergosta-7,22-diene-3,6,9-triol (1), along with six known steroids 5α,8α-epidioxy-24-ethyl-cholest-6-en-3β-ol (2), ergosterol-5,8-peroxide (3), cerevisterol (4), isocyathisterol (5), 6β-hydroxystigmast-4-en-3-one (6), 6β-hydroxy-4-campesten-3-one (7), were isolated from the fermented unpolished rice media by Periconia pseudobyssoides K5 (Periconiaceae), an endophytic fungus from medicinal plant Toona sureni (Meliaceae). The fermentation takes at 28 ± 2 °C for 30 days. The structure of new steroid (1) was elucidated by extensive spectroscopic measurements (IR, HR-ESI-TOFMS, and 1D and 2D NMR) analyses. The isolated compounds (1-7) were evaluated for heme polymerization inhibition assay (HPIA). The IC50 HPIA value of 1 is 8.24 ± 0.03 mg/ml.

Bioactive Metabolites of Serratia sp. NhPB1 Isolated from Pitcher of Nepenthes and its Application to Control Pythium aphanidermatum

Plant-associated bacteria have already been considered as the store house of bioactive compounds that confer the plant growth promotion and disease protection. Hence, the unique plant parts have already been expected to harbor diverse microbial communities with multi-beneficial properties. Based on this, the current study has been designed to identify the potential of Serratia sp. NhPB1 isolated from the pitcher of Nepenthes plant for its activity against the infamous pathogen Pythium aphanidermatum. The in vitro antifungal, plant growth promoting and enzymatic activities of the isolate indicated its promises for agricultural application. The isolate NhPB1 was also demonstrated to have positive effect on Solanum lycopersicum and Capsicum annuum, due to its plant beneficial metabolites. From the results of LC-MS/MS analysis, the isolate has also been revealed to have the ability to synthesize bioactive compounds including salicylic acid, cyclodipeptides, acyl homoserine lactone, indole-3-acetic acid, and serrawettin W1. These identified compounds and their known biological properties make the isolate characterized in the study to have significant promises as an eco-friendly solution for the improvement of agricultural productivity.

Endophytic insect pathogenic fungi-host plant-herbivore mutualism: elucidating the mechanisms involved in the tripartite interactions

Various techniques used by crop plants to evade insect pests and pathogen attacks have been documented. Among these, plant defense strategies induced by endophytic insect pathogenic fungi are arguably one of the most discussed. Endophytic fungi frequently colonize plants and inhabit their internal tissues for a portion of their lifespan without producing visible symptoms of the disease. This phenomenon is widespread and diverse in both natural and agricultural ecosystems, and is present in almost all plant organs. Many fungi can obtain nutrients by infecting and killing insects, and this ability has been developed numerous times in different fungal lineages. These species mainly consist of those in the order Hypocreales (Ascomycota), where the generalist insect pathogens, Beauveria sp. (Cordycipitaceae) and Metarhizium sp. (Clavicipitaceae) are two of the most studied endophytic entomopathogenic fungal genera. However, most fungi that kill insects do not survive in the tissues of living plants. The data published thus far show a high degree of variability and do not provide consistent explanations for the underlying mechanisms that may be responsible for these effects. This implies that available knowledge regarding the colonization of plant tissues by endophytic insect pathogenic fungi, the effects of colonization on plant metabolism, and how this contributes to a decrease in herbivore and pathogens damage is limited. To adequately utilize fungal-based products as biological control agents, these products must be effective and the reduction of pests and infection must be consistent and similar to that of chemical insecticides after application. This article discusses this possibility and highlights the benefits and the specific techniques utilized by endophytically challenged plants in invading insect pests and disease pathogens.

Bacterial and Fungal Biocontrol Agents for Plant Disease Protection: Journey from Lab to Field, Current Status, Challenges, and Global Perspectives

Plants are constantly exposed to various phytopathogens such as fungi, Oomycetes, nematodes, bacteria, and viruses. These pathogens can significantly reduce the productivity of important crops worldwide, with annual crop yield losses ranging from 20% to 40% caused by various pathogenic diseases. While the use of chemical pesticides has been effective at controlling multiple diseases in major crops, excessive use of synthetic chemicals has detrimental effects on the environment and human health, which discourages pesticide application in the agriculture sector. As a result, researchers worldwide have shifted their focus towards alternative eco-friendly strategies to prevent plant diseases. Biocontrol of phytopathogens is a less toxic and safer method that reduces the severity of various crop diseases. A variety of biological control agents (BCAs) are available for use, but further research is needed to identify potential microbes and their natural products with a broad-spectrum antagonistic activity to control crop diseases. This review aims to highlight the importance of biocontrol strategies for managing crop diseases. Furthermore, the role of beneficial microbes in controlling plant diseases and the current status of their biocontrol mechanisms will be summarized. The review will also cover the challenges and the need for the future development of biocontrol methods to ensure efficient crop disease management for sustainable agriculture.

Epigenetic manipulation for secondary metabolite activation in endophytic fungi: current progress and future directions

Fungal endophytes have emerged as a promising source of secondary metabolites with significant potential for various applications in the field of biomedicine. The biosynthetic gene clusters of endophytic fungi are responsible for encoding several enzymes and transcriptional factors that are involved in the biosynthesis of secondary metabolites. The investigation of fungal metabolic potential at genetic level faces certain challenges, including the synthesis of appropriate amounts of chemicals, and loss of the ability of fungal endophytes to produce secondary metabolites in an artificial culture medium. Therefore, there is a need to delve deeper into the field of fungal genomics and transcriptomics to explore the potential of fungal endophytes in generating secondary metabolites governed by biosynthetic gene clusters. The silent biosynthetic gene clusters can be activated by modulating the chromatin structure using chemical compounds. Epigenetic modification plays a significant role by inducing cryptic gene responsible for the production of secondary metabolites using DNA methyl transferase and histone deacetylase. CRISPR-Cas9-based genome editing emerges an effective tool to enhance the production of desired metabolites by modulating gene expression. This review primarily focuses on the significance of epigenetic elicitors and their capacity to boost the production of secondary metabolites from endophytes. This article holds the potential to rejuvenate the drug discovery pipeline by introducing new chemical compounds.

Clonostachys rosea, a marine algal endophyte, as an alternative source of chrysin and its anticancer effect

Endophytic fungi were isolated from the marine green alga Chaetomorpha antennina and identified as Clonostachys rosea through molecular analysis. C. rosea was grown in a tryptophan medium for 21 days and after that, the metabolites were extracted by ethyl acetate. The ethyl acetate extract showed a high cytotoxic effect on MCF-7 cells. GC-MS analysis of the ethyl acetate extract revealed the presence of many compounds, and chrysin was one of the major compounds among them. Hence, further studies were concentrated on chrysin, as it was assumed to be the major attributor to the potent cytotoxicity, based on its high anticancer efficacies reported earlier. The fungal ethyl acetate extract had been analysed for chrysin using HPTLC and compared its Rf value with authentic chrysin and it was matched. Further, the purified fungal chrysin was structurally elucidated using techniques like LC-MS and NMR analyses. Quantification revealed that C. rosea produced 1050 mg/L of chrysin. This surplus production of chrysin was the major significance of the study. The purified fungal chrysin was found to be highly cytotoxic to MCF-7 cells with a low IC50 value 35.5 ± 0.6 µM. Furthermore, DNA fragmentation and apoptosis analysis indicated the selective inhibition of MCF-7 by DNA damage. Thus, the present study implies that C. rosea is an alternative source and new method for surplus production of chrysin in the tryptophan medium. All results indicate that the marine algae endophytic C. rosa produces chrysin, and for the first time, an excess amount of production was revealed by the study.

Coffee-Associated Endophytes: Plant Growth Promotion and Crop Protection

Endophytic microbes are a ubiquitous group of plant-associated communities that colonize the intercellular or intracellular host tissues while providing numerous beneficial effects to the plants. All the plant species are thought to be associated with endophytes, majorly constituted with bacteria and fungi. During the last two decades, there has been a considerable movement toward the study of endophytes associated with coffee plants. In this review, the main consideration is given to address the coffee-associated endophytic bacteria and fungi, particularly their action on plant growth promotion and the biocontrol of pests. In addition, we sought to identify and analyze the gaps in the available research. Additionally, the potential of endophytes to improve the quality of coffee seeds is briefly discussed. Even though there are limited studies on the subject, the potentiality of coffee endophytes in plant growth promotion through enhancing nitrogen fixation, availability of minerals, nutrient absorption, secretion of phytohormones, and other bioactive metabolites has been well recognized. Further, the antagonistic effect against various coffee pathogenic bacteria, fungi, nematodes, and also insect pests leads to the protection of the crop. Furthermore, it is recognized that endophytes enhance the sensory characteristics of coffee as a new field of study.

In vivo and In vitro evaluation of the antifungal activity of the PGPR Bacillus amyloliquefaciens RaSh1 (MZ945930) against Alternaria alternata with growth promotion influences on Capsicum annuum L. plants

Alternaria alternata that threatens pepper production and causes major economic harm is responsible for the leaf spot/blight disease. Chemical fungicides have been widely employed; unfortunately, fungicidal resistance is a current concern. Therefore, finding new environmentally friendly biocontrol agents is a future challenge. One of these friendly solutions is the use of bacterial endophytes that have been identified as a source of bioactive compounds. The current study investigates the in vivo and in vitro fungicidal potential of Bacillus amyloliquefaciens RaSh1 (MZ945930) against pathogenic A. alternata. In vitro, the results revealed that RaSh1 exhibited strong antagonistic activity against A. alternata. In addition to this, we inoculated pepper (Capsicum annuum L.) plants with B. amyloliquefaciens RaSh1 and infected them with A. alternata. As a result of A. alternata infection, which generated the highest leaf spot disease incidence (DI), the plant's growth indices and physio-biochemical characteristics significantly decreased, according to our findings. Our results also showed the abnormal and deformed cell structure using light and electron microscopy of A. alternata-infected leaves compared with other treatments. However, DI was greatly reduced with B. amyloliquefaciens RaSh1 application (40%) compared to pepper plants infected with A. alternata (80%), and this led to the largest increases in all identified physio-biochemical parameters, including the activity of the defense-related enzymes. Moreover, inoculation of pepper plants with B. amyloliquefaciens RaSh1 decreased electrolyte leakage by 19.53% and MDA content by 38.60% as compared to A. alternata infected ones. Our results show that the endophyte B. amyloliquefaciens RaSh1 has excellent potential as a biocontrol agent and positively affects pepper plant growth.

An insight into endophytic antimicrobial compounds: an updated analysis

Resistance in micro-organisms against antimicrobial compounds is an emerging phenomenon in the modern era as compared to the traditional world which brings new challenges to discover novel antimicrobial compounds from different available sources, such as, medicinal plants, various micro-organisms, like, bacteria, fungi, algae, actinomycetes, and endophytes. Endophytes reside inside the plants without exerting any harmful impact on the host plant along with providing ample of benefits. In addition, they are capable of producing diverse antimicrobial compounds similar to their host, allowing them to serve as useful micro-organism for a range of therapeutic purposes. In recent years, a large number of studies on the antimicrobial properties of endophytic fungi have been carried out globally. These antimicrobials have been used to treat various bacterial, fungal, and viral infections in humans. In this review, the potential of fungal endophytes to produce diverse antimicrobial compounds along with their various benefits to their host have been focused on. In addition, classification systems of endophytic fungi as well as the need for antimicrobial production with genetic involvement and some of the vital novel antimicrobial compounds of endophytic origin can further be utilized in the pharmaceutical industries for various formulations along with the role of nanoparticles as antimicrobial agents have been highlighted.

Recent Advances in Using Natural Antibacterial Additives in Bioactive Wound Dressings

Wound care is a global health issue with a financial burden of up to US $96.8 billion annually in the USA alone. Chronic non-healing wounds which show delayed and incomplete healing are especially problematic. Although there are more than 3000 dressing types in the wound management market, new developments in more efficient wound dressings will require innovative approaches such as embedding antibacterial additives into wound-dressing materials. The lack of novel antibacterial agents and the misuse of current antibiotics have caused an increase in antimicrobial resistance (AMR) which is estimated to cause 10 million deaths by 2050 worldwide. These ongoing challenges clearly indicate an urgent need for developing new antibacterial additives in wound dressings targeting microbial pathogens. Natural products and their derivatives have long been a significant source of pharmaceuticals against AMR. Scrutinising the data of newly approved drugs has identified plants as one of the biggest and most important sources in the development of novel antibacterial drugs. Some of the plant-based antibacterial additives, such as essential oils and plant extracts, have been previously used in wound dressings; however, there is another source of plant-derived antibacterial additives, i.e., those produced by symbiotic endophytic fungi, that show great potential in wound dressing applications. Endophytes represent a novel, natural, and sustainable source of bioactive compounds for therapeutic applications, including as efficient antibacterial additives for chronic wound dressings. This review examines and appraises recent developments in bioactive wound dressings that incorporate natural products as antibacterial agents as well as advances in endophyte research that show great potential in treating chronic wounds.

Uniting the Role of Endophytic Fungi against Plant Pathogens and Their Interaction

Endophytic fungi are used as the most common microbial biological control agents (MBCAs) against phytopathogens and are ubiquitous in all plant parts. Most of the fungal species have roles against a variety of plant pathogens. Fungal endophytes provide different services to be used as pathogen control agents, using an important aspect in the form of enhanced plant growth and induced systemic resistance, produce a variety of antifungal secondary metabolites (lipopeptides, antibiotics and enzymes) through colonization, and compete with other pathogenic microorganisms for growth factors (space and nutrients). The purpose of this review is to highlight the biological control potential of fungal species with antifungal properties against different fungal plant pathogens. We focused on the introduction, biology, isolation, identification of endophytic fungi, and their antifungal activity against fungal plant pathogens. The endosymbionts have developed specific genes that exhibited endophytic behavior and demonstrated defensive responses against pathogens such as antibiosis, parasitism, lytic enzyme and competition, siderophore production, and indirect responses by induced systemic resistance (ISR) in the host plant. Finally, different microscopic detection techniques to study microbial interactions (endophytic and pathogenic fungal interactions) in host plants are briefly discussed.

Metabolites of endophytic fungi isolated from leaves of Bauhinia variegata exhibit antioxidant activity and agonist activity on peroxisome proliferator-activated receptors α, β/δ and γ

Diabetes mellitus is a metabolic disorder that affects millions of people worldwide and is linked to oxidative stress and inflammation. Thiazolidinediones (TZD) improve insulin sensitization and glucose homeostasis mediated by the activation of peroxisome proliferator-activated receptors γ (PPARγ) in patients with type 2 diabetes. However, their use is associated with severe adverse effects such as loss of bone mass, retention of body fluids, liver and heart problems, and increased risk of bladder cancer. Partial PPARγ agonists can promote the beneficial effects of thiazolidinediones with fewer adverse effects. Endophytic fungi colonize plant tissues and have a particularly active metabolism caused by the interaction with them, which leads to the production of natural products with significant biological effects that may be like that of the colonized plant. Here, we identify seven endophytic fungi isolated from Bauhinia variegata leaves that have antioxidant activities. Also, one of the extracts presented pan-agonist activity on PPAR, and another showed activity in PPARα and PPARβ/δ. A better understanding of this relationship could help to comprehend the mechanism of action of antioxidants in treating diabetes and its complications. Moreover, compounds with these capabilities to reduce oxidative stress and activate the receptor that promotes glucose homeostasis are promising candidates in treatment of diabetes.

Two sydowic acid derivatives and a sulfonyl metabolite from the endophytic fungus Aspergillus sydowii

Two new sydowic acid derivatives, a pair of enantiomers, involving (+)-sydowiccal (1a) and (-)-sydowiccal (1b), a new sulfonyl metabolite of 2-methoxy-5-methyl-3-(methylsulfonyl)phenol (2), as well as three known sydowic acid derivatives, were isolated from Aspergillus sydowii, an endophytic fungus of Rhododendron mole. The structures of these new compounds were elucidated by analyzing their NMR and HRESIMS data, and the absolute configurations of enantiomers were determined on the basis of the CD spectrum. Three new metabolites showed weak anti-inflammation on nitric oxide (NO) production in LPS-induced RAW 264.7 cells.

Five new secondary metabolites from an endophytic fungus Phomopsis sp. SZSJ-7B

Two previously undescribed lactones, phomolides A and B (1 and 2), and three new sesquiterpenoids, phomenes A-C (3-5), together with one known compound, colletotricholide A (6), were isolated from the endophytic fungus Phomopsis sp. SZSJ-7B. Their chemical structures, including the absolute configurations, were comprehensively established by extensive analyses of NMR, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism powered by theoretical calculations, and X-ray diffractions. Moreover, the cytotoxic and antibacterial activities of compounds 1-6 were also evaluated, and the results demonstrated that compound 2 showed significant antibacterial effects towards methicillin-resistant Staphylococcus aureus and S. aureus strains with minimum inhibitory concentration as low as 6.25 μg/ml, which was comparable to that of the clinical drug vancomycin. Moreover, all compounds showed no cytotoxic activity.

Endophytes and their potential in biotic stress management and crop production

Biotic stress is caused by harmful microbes that prevent plants from growing normally and also having numerous negative effects on agriculture crops globally. Many biotic factors such as bacteria, fungi, virus, weeds, insects, and nematodes are the major constrains of stress that tends to increase the reactive oxygen species that affect the physiological and molecular functioning of plants and also led to the decrease in crop productivity. Bacterial and fungal endophytes are the solution to overcome the tasks faced with conventional farming, and these are environment friendly microbial commodities that colonize in plant tissues without causing any damage. Endophytes play an important role in host fitness, uptake of nutrients, synthesis of phytohormone and diminish the injury triggered by pathogens via antibiosis, production of lytic enzymes, secondary metabolites, and hormone activation. They are also reported to help plants in coping with biotic stress, improving crops and soil health, respectively. Therefore, usage of endophytes as biofertilizers and biocontrol agent have developed an eco-friendly substitute to destructive chemicals for plant development and also in mitigation of biotic stress. Thus, this review highlighted the potential role of endophytes as biofertilizers, biocontrol agent, and in mitigation of biotic stress for maintenance of plant development and soil health for sustainable agriculture.

Metabolites of medicine food homology-derived endophytic fungi and their activities

Medicine food homology (MFH) substances not only provide essential nutrients as food but also have corresponding factors that can prevent and help treat nutritional imbalances, chronic disease, and other related issues. Endophytic fungi associated with plants have potential for use in drug discovery and food therapy. However, the endophytic fungal metabolites from MFH plants and their effects have been overlooked. Therefore, this review focuses on the various biological activities of 108 new metabolites isolated from 53 MFH-derived endophytic fungi. The paper explores the potential nutritional and medicinal value of metabolites of MFH-derived endophytic fungi for food and medical applications. This research is important for the future development of effective, safe, and nontoxic therapeutic nutraceuticals for the prevention and treatment of human diseases.

Exploring the Potential Applications of Paecilomyceslilacinus 112

Microorganisms are widely used to obtain biostimulants that can facilitate the assimilation of nutrients, ensuring high crop yield and quality. A particular category of biostimulants are protein hydrolyzates (PH), obtained from microbial cultures grown on a nutrient medium. In the present study, Paecilomyces lilacinus 112, an endophytic fungus isolated from soil, was tested to determine its effect on the growth promotion of tomato seedlings in greenhouse conditions. Additionally, other beneficial features of the P.lilacinus isolate were evaluated via several tests: antagonism against plant pathogenic fungi, production of secondary useful metabolites, and solubilization of vital micronutrients. Out of the tested pathogens, P.lilacinus exhibited the highest antifungal activity against a Cladosporium isolate (inhibition of 66.3%), followed by Rhizoctonia. solani (52.53%), and Sclerotinia sclerotiorum (50.23%). Paecilomyceslilacinus 112 was able to secrete hydrolytic enzymes and siderophores, and solubilize zinc and phosphorus. In the tomato treatment, the application of PH obtained from fungal cultivation on a feather medium led to the following increases in plant growth parameters: 3.54-fold in plant biomass; 3.26-fold in plant height, 1.28-fold in plant diameter; 1.5-fold in the number of branches/plant; and 1.43-fold in the number of leaves/plant, as compared to water treatment. The application of this isolate can be of benefit to bioeconomy because keratin wastes are valorized and returned, in agriculture, contributing to renewable natural resources.

Fungal Endophytes to Combat Biotic and Abiotic Stresses for Climate-Smart and Sustainable Agriculture

The agricultural sustainability concept considers higher food production combating biotic and abiotic stresses, socio-economic well-being, and environmental conservation. On the contrary, global warming-led climatic changes have appalling consequences on agriculture, generating shifting rainfall patterns, high temperature, CO2, drought, etc., prompting abiotic stress conditions for plants. Such stresses abandon the plants to thrive, demoting food productivity and ultimately hampering food security. Though environmental issues are natural and cannot be regulated, plants can still be enabled to endure these abnormal abiotic conditions, reinforcing the stress resilience in an eco-friendly fashion by incorporating fungal endophytes. Endophytic fungi are a group of subtle, non-pathogenic microorganisms establishing a mutualistic association with diverse plant species. Their varied association with the host plant under dynamic environments boosts the endogenic tolerance mechanism of the host plant against various stresses via overall modulations of local and systemic mechanisms accompanied by higher antioxidants secretion, ample enough to scavenge Reactive Oxygen Species (ROS) hence, coping over-expression of defensive redox regulatory system of host plant as an aversion to stressed condition. They are also reported to ameliorate plants toward biotic stress mitigation and elevate phytohormone levels forging them worthy enough to be used as biocontrol agents and as biofertilizers against various pathogens, promoting crop improvement and soil improvement, respectively. This review summarizes the present-day conception of the endophytic fungi, their diversity in various crops, and the molecular mechanism behind abiotic and biotic resistance prompting climate-resilient aided sustainable agriculture.

Secondary Metabolism Gene Diversity and Cocultivation toward Isolation and Identification of Potent Bioactive Compounds Producing Bacterial Strains from Thailand's Natural Resources

Thailand was proposed to be rich unexplored source of microorganisms, especially bacterial strains. There should be bacteria with high secondary metabolite production potential in the natural resources that are still unidentified. Moreover, they might not produce secondary metabolites in standard laboratory culture condition after isolation, in which coculture condition would help us pursuing the bacteria to produce bioactive metabolites. Here, we aimed to identify new bacterial strains with high secondary metabolite production potential from Thailand's natural resources. To achieve the goal, we performed bacteria isolation, phylogenetic analysis, degenerate PCR of secondary metabolism genes, cocultivation, antibacterial analysis, and HPLC chemical profiling. We isolated distinct 40 bacterial strains, which have over 98% 16S rRNA sequence similarity with known species. There were 22, 31, and 29 strains giving positive PCR amplification of NRPS, PKS, and TPS genes, respectively. Among them, Bacillus licheniformis RSUCC0101 had the highest number of PCR products, 26. In standard single culture condition, crude extracts prepared from Bacillus safensis RSUCC0021 and Bacillus amyloliquefaciens RSUCC0282 could inhibit the growth of Staphylococcus aureus ATCC25923. Furthermore, the cocultivation and HPLC analyses showed that the extracts prepared from 3 pairs of culture between Staphylococcus sp. RSUCC0020, Micrococcus luteus RSUCC0053, Staphylococcus sp. RSUCC0087, and Staphylococcus pasteuri RSUCC0090 could inhibit the growth of Staphylococcus aureus ATCC25923 and produced distinct chemical profiles from their single culture condition. Our study led to the isolation and identification of several promising bacterial strains for production of secondary metabolites that might be useful in biomedical applications.

Prospecting potential of endophytes for modulation of biosynthesis of therapeutic bioactive secondary metabolites and plant growth promotion of medicinal and aromatic plants

Medicinal and aromatic plants possess pharmacological properties (antidiabetes, anticancer, antihypertension, anticardiovascular, antileprosy, etc.) because of their potential to synthesize a wide range of therapeutic bioactive secondary metabolites. The concentration of bioactive secondry metabolites depends on plant species, local environment, soil type and internal microbiome. The internal microbiome of medicinal plants plays the crucial role in the production of bioactive secondary metabolites, namely alkaloids, steroids, terpenoids, peptides, polyketones, flavonoids, quinols and phenols. In this review, the host specific secondry metabolites produced by endophytes, their therapeutic properties and host-endophytes interaction in relation to production of bioactive secondry metaboloites and the role of endophytes in enhancing the production of bioactive secondry metabolites is discussed. How biological nitrogen fixation, phosphorus solubilization, micronutrient uptake, phytohormone production, disease suppression, etc. can play a vital role in enhacing the plant growth and development.The role of endophytes in enhancing the plant growth and content of bioactive secondary metabolites in medicinal and aromatic plants in a sustainable mode is highlighted.

The hidden world within plants: metatranscriptomics unveils the complexity of wood microbiomes

The importance of plants as complex entities influenced by genomes of the associated microorganisms is now seen as a new source of variability for a more sustainable agriculture, also in the light of ongoing climate change. For this reason, we investigated through metatranscriptomics whether the taxa profile and behaviour of microbial communities associated with the wood of 20-year-old grapevine plants are influenced by the health status of the host. We report for the first time a metatranscriptome from a complex tissue in a real environment, highlighting that this approach is able to define the microbial community better than referenced transcriptomic approaches. In parallel, the use of total RNA enabled the identification of bacterial taxa in healthy samples that, once isolated from the original wood tissue, displayed potential biocontrol activities against a wood-degrading fungal taxon. Furthermore, we revealed an unprecedented high number of new viral entities (~120 new viral species among 180 identified) associated with a single and limited environment and with potential impact on the whole holobiont. Taken together, our results suggest a complex multitrophic interaction in which the viral community also plays a crucial role in raising new ecological questions for the exploitation of microbial-assisted sustainable agriculture.

Biological and Agronomic Traits of the Main Halophytes Widespread in the Mediterranean Region as Potential New Vegetable Crops

Salinity is one of the oldest and most serious environmental problems in the world. The increasingly widespread salinization of soils and water resources represents a growing threat to agriculture around the world. A strategy to cope with this problem is to cultivate salt-tolerant crops and, therefore, it is necessary to identify plant species that are naturally adapted to high-salinity conditions. In this review, we focus our attention on some plant species that can be considered among the most representative halophytes of the Mediterranean region; they can be potential resources, such as new or relatively new vegetable crops, to produce raw or minimally processed (or ready-to-eat) products, considering their nutritional properties and nutraceuticals. The main biological and agronomic characteristics of these species and the potential health risks due to mycotoxigenic fungi have been analyzed and summarized in a dedicated section. The objective of this review is to illustrate the main biological and agronomical characteristics of the most common halophytic species in the Mediterranean area, which could expand the range of leafy vegetables on the market.

Production of Non-Volatile Metabolites from Sooty Molds and Their Bio-Functionalities

In the current study, eleven sooty mold isolates were collected from different tropical host plants. The isolates were identified under Capnodium, Leptoxyphium and Trichomerium, based on morphology and phylogeny. For the secondary metabolite analysis, the isolates were grown on Potato Dextrose Broth (PDB). The well-grown mycelia were filtered and extracted over methanol (MeOH). The metabolites in the growth medium (or filtrate) were extracted over ethyl acetate (EtOAc). The antifungal activities of each crude extract were tested over Alternaria sp., Colletotrichum sp., Curvularia sp., Fusarium sp. and Pestalotiopsis sp. The metabolites were further tested for their total phenolic, flavonoid and protein content prior to their antioxidant and anti-fungal potential evaluation. The MeOH extracts of sooty molds were enriched with proteins and specifically inhibited Curvularia sp. The total phenolic content and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) activity was largely recovered from the filtrate corresponding to the inhibition of Alternaria sp.; while the flavonoid and free radical reduction suggested a relative induction of growth of the Fusarium sp., Colletotrichum sp. and Pestalotiopsis sp. Hence, this study reveals the diversity of sooty molds in Thailand by a modern phylogenetic approach. Furthermore, the preliminary screening of the isolates reveals the potential of finding novel compounds and providing insights for the future research on secondary metabolites of bio-trophic fungi and their potential usage on sustainable agriculture.

Plants and endophytes – a partnership for the coumarin production through the microbial systems

Plant-based secondary metabolite production system is well established. However, host–endophyte interaction in the production of secondary metabolite is a new less exploited area that is overcoming barriers and evolving as one of the prospective fields. Endophytes such as bacteria or fungi have the ability to produce some of the secondary metabolites that mimic the plant metabolites therefore escaping the host defence system. Coumarin is one such metabolite with immense biological functions. Most of the studies have demonstrated coumarin production from fungal endophytes but not bacterial endophytes. Herein, we present an overview of all the coumarin derivatives produced from endophytic sources and their biosynthetic pathways. Furthermore, the review also throws light on the isolation of these coumarins and different derivatives with respect to their biological activity. The biotransformation of coumarin derivatives by the action of endophytic fungi is also elaborated. The present review provides an insight on the challenges faced in the coumarin production through fungal endophytes.

Fungal Endophytes and Their Role in Agricultural Plant Protection against Pests and Pathogens

Virtually all examined plant species harbour fungal endophytes which asymptomatically infect or colonize living plant tissues, including leaves, branches, stems and roots. Endophyte-host interactions are complex and span the mutualist-pathogen continuum. Notably, mutualist endophytes can confer increased fitness to their host plants compared with uncolonized plants, which has attracted interest in their potential application in integrated plant health management strategies. In this review, we report on the many benefits that fungal endophytes provide to agricultural plants against common non-insect pests such as fungi, bacteria, nematodes, viruses, and mites. We report endophytic modes of action against the aforementioned pests and describe why this broad group of fungi is vitally important to current and future agricultural practices. We also list an extensive number of plant-friendly endophytes and detail where they are most commonly found or applied in different studies. This review acts as a general resource for understanding endophytes as they relate to potential large-scale agricultural applications.

A Metabolomic Study of Epichloë Endophytes for Screening Antifungal Metabolites

Epichloë endophytes, fungal endosymbionts of Pooidae grasses, are commonly utilized in forage and turf industries because they produce beneficial metabolites that enhance resistance against environmental stressors such as insect feeding and disease caused by phytopathogen infection. In pastoral agriculture, phytopathogenic diseases impact both pasture quality and animal production. Recently, bioactive endophyte strains have been reported to secrete compounds that significantly inhibit the growth of phytopathogenic fungi in vitro. A screen of previously described Epichloë-produced antifeedant and toxic alkaloids determined that the antifungal bioactivity observed is not due to the production of these known metabolites, and so there is a need for methods to identify new bioactive metabolites. The process described here is applicable more generally for the identification of antifungals in new endophytes. This study aims to characterize the fungicidal potential of novel, ‘animal friendly’ Epichloë endophyte strains NEA12 and NEA23 that exhibit strong antifungal activity using an in vitro assay. Bioassay-guided fractionation, followed by metabolite analysis, identified 61 metabolites that, either singly or in combination, are responsible for the observed bioactivity. Analysis of the perennial ryegrass-endophyte symbiota confirmed that NEA12 and NEA23 produce the prospective antifungal metabolites in symbiotic association and thus are candidates for compounds that promote disease resistance in planta. The “known unknown” suite of antifungal metabolites identified in this study are potential biomarkers for the selection of strains that enhance pasture and turf production through better disease control.

Metabolites Produced by Fungi against Fungal Phytopathogens: Review, Implementation and Perspectives

Many fungi, especially endophytes, have been found to produce multiple benefits in their plant hosts, with many of these benefits associated with the protection of plants against fungal diseases. This fact could be used in the development of new bio-products that could gradually reduce the need for chemical fungicides, which have been associated with multiple health and environmental problems. However, the utilization of the living organism may present several issues, such as an inconsistency in the results obtained and more complicated management and application, as fungal species are highly influenced by environmental conditions, the type of relationship with the plant host and interaction with other microorganisms. These issues could be addressed by using the bioactive compounds produced by the fungus, in cases where they were responsible for positive effects, instead of the living organism. Multiple bioactive compounds produced by fungal species, especially endophytes, with antifungal properties have been previously reported in the literature. However, despite the large amount of these metabolites and their potential, extensive in-field application on a large scale has not yet been implemented. In the present review, the main aspects explaining this limited implementation are analyzed, and the present and future perspectives for its development are discussed.

Model Application of Entomopathogenic Fungi as Alternatives to Chemical Pesticides: Prospects, Challenges, and Insights for Next-Generation Sustainable Agriculture

In the past few decades, the control of pests and diseases of cultivated plants using natural and biological measures has drawn increasing attention in the quest to reduce the level of dependence on chemical products for agricultural production. The use of living organisms, predators, parasitoids, and microorganisms, such as viruses, bacteria, and fungi, has proven to be a viable and sustainable pest management technique. Among the aforementioned, fungi, most importantly the insect-pathogenic species, have been in use for more than 150years. These include the most popular strains belonging to the genera Beauveria, Metarhizium, Isaria, Hirsutella, and Lecanicillium. Their application is usually through an inundative approach, which inherently involves exposure of the fungal spores to unfavorable humidity, temperature, and solar radiation conditions. These abiotic factors reduce the persistence and efficacy of these insect-pathogenic fungi. Despite these limitations, over 170 strains have been formulated as mycopesticides and are available for commercial use. In the last few decades, numerous studies have suggested that these species of entomopathogenic fungi (EPF) offer far more benefits and have broader ecological functions than hitherto presumed. For instance, aside from their roles as insect killers, it has been well established that they also colonize various host plants and, hence, provide other benefits including plant pathogen antagonism and plant growth promotion and serve as sources of novel bioactive compounds and secondary metabolites, etc. In this light, the potential of EPF as alternatives or perhaps as supplements to chemical pesticides in plant protection is discussed in this review. The paper highlights the numerous benefits associated with endophytic fungal entomopathogen and host plant associations, the mechanisms involved in mediating plant defense against pests and pathogens, and the general limitations to the use of EPF in plant protection. A deeper understanding of these plant host-fungus-insect relationships could help unveil the hidden potentials of fungal endophytes, which would consequently increase the level of acceptance and adoption by users as an integral part of pest management programs and as a suitable alternative to chemical inputs toward sustainable crop production.

Identification, semisynthesis, and anti-inflammatory evaluation of 2,3-seco-clavine-type ergot alkaloids from human intestinal fungus Aspergillus fumigatus CY018

Intestinal commensal fungi are vital to human health, and their secondary metabolites play a key role in the reciprocal relationship. In the present study, the first example of 2,3-seco ergot alkaloids belonging to clavine-type were isolated from the fermentation of human intestinal fungus Aspergillus fumigatus CY018, including two pairs of diastereoisomers, secofumigaclavines A (3) and B (4) and secofumigaclavines C (5) and D (6), one analogue features a highly unsaturated skeleton, secofumigaclavine E (7), along with two known ones, fumigaclavines C (1) and D (2). Their structures were identified based on extensive spectroscopic data in a combination of quantum chemical calculations. Moreover, a single-step operation of semi-synthetic reaction based on riboflavin (RF)-dependent photocatalysis was performed to obtain the novel 2,3-seco ergot alkaloids 3 and 5 from their biosynthetic precursors 1 and 2. All the isolated compounds were evaluated for their anti-inflammatory activity. Among them, secofumigaclavine B (4) could bind to MD2 with a low micromole level of the equilibrium dissociation constant measured by surface plasmon resonance (SPR), and suppress TLR4-mediated NF-κB signaling pathway in RAW264.7 cells, resulting in its anti-inflammatory effect. Molecular dynamics revealed that amino acid residue Tyr131 played a key role in the interaction of secofumigaclavine B (4) with MD2. These findings suggested that secofumigaclavine B (4) could be considered as a potential candidate for the development of MD2 inhibitors.

Cure lies in nature: medicinal plants and endophytic fungi in curbing cancer

Success of targeted cancer treatment modalities has generated an ambience of plausible cure for cancer. However, cancer remains to be the major cause of mortality across the globe. The emergence of chemoresistance, relapse after treatment and associated adverse effects has posed challenges to the present therapeutic regimes. Thus, investigating new therapeutic agents of natural origin and delineating the underlying mechanism of action is necessary. Since ages and still in continuum, the phytochemicals have been the prime source of identifying bioactive agents against cancer. They have been exploited for isolating targeted specific compounds to modulate the key regulating signaling pathways of cancer pathogenesis and progression. Capsaicin (alkaloid compound in chilli), catechin, epicatechin, epigallocatechin and epigallocatechin-3-gallate (phytochemicals in green tea), lutein (carotenoid found in yellow fruits), Garcinol (phenolic compound present in kokum tree) and many other naturally available compounds are also very valuable to develop the drugs to treat the cancer. An alternate repository of similar chemical diversity exists in the form of endophytic fungi inhabiting the medicinal plants. There is a high diversity of plant associated endophytic fungi in nature which are potent producers of anti-cancer compounds and offers even stronger hope for the discovery of an efficient anti-cancer drug. These fungi provide various bioactive molecules, such as terpenoids, flavonoids, alkaloids, phenolic compounds, quinines, steroids etc. exhibiting anti-cancerous property. The review discusses the relevance of phytochemicals in chemoprevention and as modulators of miRNA. The perspective advocates the imperative role of anti-cancerous secondary metabolites containing repository of endophytic fungi, as an alternative route of drug discovery.

Penpolonin A-E, cytotoxic α-pyrone derivatives from Penicillium polonicum

Five new α-pyrone derivatives, named penpolonin A-E (1-5), together with two known compounds (6-7) were acquired from the endophytic fungus Penicillium polonicum isolated from the roots of Camptotheca acuminata Decne. Their structures were established by combination of NMR and HRESIMS data and the absolute configurations of 1-5 were determined by NMR calculations and comparison of experimental and calculated ECD data. Compounds 3 and 7 exhibited moderate cytotoxicity against Hep-2, TU212 human laryngeal cancer cells with IC₅₀ values ranging from 31.6 to 45.1 μg/ml, compound 4 showed weak cytotoxicity against the Hep-2 and TU212 cell lines with IC₅₀ values of 69.2 and 68.7 μg/ml.

A Technical System for the Large-Scale Application of Metabolites From Paecilomyces variotii SJ1 in Agriculture

Compared with endophytes, metabolites from endophytes (MEs) have great potential in agriculture. However, a technique for industrializing the production of MEs is still scarce. Moreover, the establishment of effective methods for evaluating the quality of MEs is hampered by the fact that some compounds with beneficial effects on crops have not been clearly identified. Herein, a system was established for the production, quality control and application of MEs by using the extract from Paecilomyces variotii SJ1 (ZNC). First, the extraction conditions of ZNC were optimized through response surface methodology, after which each batch (500 L) met the consumption requirements of crops in 7,467 hectares. Then, chromatographic fingerprinting and enzyme-linked immunosorbent assay were applied to evaluate the similarity and specificity of unknown effective components in ZNC, ensuring a similarity of more than 90% and a quantitative accuracy of greater than 99.9% for the products from different batches. Finally, the bioactivity of industrially produced ZNC was evaluated in the field, and it significantly increased the potato yields by 4.4–10.8%. Overall, we have established a practical technical system for the large-scale application of ZNC in agriculture.

Changes in Bacterial Endophyte Community Following Aspergillus flavus Infection in Resistant and Susceptible Maize Kernels

Aspergillus flavus (A. flavus)-mediated aflatoxin contamination in maize is a major global economic and health concern. As A. flavus is an opportunistic seed pathogen, the identification of factors contributing to kernel resistance will be of great importance in the development of novel mitigation strategies. Using V3–V4 bacterial rRNA sequencing and seeds of A. flavus-resistant maize breeding lines TZAR102 and MI82 and a susceptible line, SC212, we investigated kernel-specific changes in bacterial endophytes during infection. A total of 81 bacterial genera belonging to 10 phyla were detected. Bacteria belonging to the phylum Tenericutes comprised 86–99% of the detected phyla, followed by Proteobacteria (14%) and others (<5%) that changed with treatments and/or genotypes. Higher basal levels (without infection) of Streptomyces and Microbacterium in TZAR102 and increases in the abundance of Stenotrophomonas and Sphingomonas in MI82 following infection may suggest their role in resistance. Functional profiling of bacteria using 16S rRNA sequencing data revealed the presence of bacteria associated with the production of putative type II polyketides and sesquiterpenoids in the resistant vs. susceptible lines. Future characterization of endophytes predicted to possess antifungal/ anti-aflatoxigenic properties will aid in their development as effective biocontrol agents or microbiome markers for maize aflatoxin resistance.

Fungal Endophytes of Tahiti Lime (Citrus citrus × latifolia) and Their Potential for Control of Colletotrichum acutatum J. H. Simmonds Causing Anthracnose

Colletotrichum acutatum is one of the causal agents of anthracnose in several crops, and of post-flowering fruit drop (PFD) in citrus and key lime anthracnose (KLA). The pathogen normally attacks flowers, causing lesions only in open flowers. Under very favorable conditions, however, it can also affect flower buds and small fruits, causing complete rotting of the fruit and a premature fall, resulting in major economic crop losses. We isolated endophytic fungi from Tahiti lime to evaluate its diversity, verify its antagonistic capacity against the phytopathogen Colletotrichum acutatum C-100 in dual tests, and evaluate the ability of various endophytic agents to control flowers with induced anthracnose. 138 fungal isolates were obtained from 486 fragments of branches, leaves, and fruit; from which 15 species were identified morphologically. A higher isolation frequency was found in branches and leaves, with a normal level of diversity compared to other citrus species. Of the 15 morphospecies, 5 were trialed against C. acutatum in antagonism tests, resulting in a finding of positive inhibition. 2 endophytic fungi from the antagonism tests demonstrated high inhibition of the phytopathogen, and were thus used in in vivo tests with Tahiti lime flowers, applied in a spore solution. Spore solutions of two molecularly identified species, Xylaria adscendens, and Trichoderma atroviride, reduced the lesions caused by the phytopathogen in these in vivo tests. The finding that these endophytes react antagonistically against C. acutatum may make them good candidates for further biological control research in an agroindustry that requires environmental sustainability.

Eremophilane Sesquiterpenes and Benzene Derivatives from the Endophyte Microdiplodia sp. WGHS5

Three new eremophilane sesquiterpenes phomadecalins G-I (1-3) and two new benzene derivatives microdiplzenes A and B (12 and 13), together with nine known eremophilane sesquiterpenes (4-11 and 14) were isolated from an endophytic fungus, Microdiplodia sp. WGHS5. Their structures were elucidated by the interpretation of HR-ESI-MS and NMR data; meanwhile, the absolute configurations of new compounds were determined on the base of ECD calculations. All compounds were evaluated for the antimicrobial activities and antiproliferative effect on human gastric cancer cell lines (BGC-823).

Biocontrol Potential of Grapevine Endophytic and Rhizospheric Fungi Against Trunk Pathogens

Grapevine Trunk Diseases (GTDs) are a major challenge to the grape industry worldwide. GTDs are responsible for considerable loss of quality, production, and vineyard longevity. Seventy-five percent of Chilean vineyards are estimated to be affected by GTDs. GTDs are complex diseases caused by several fungi species, including members of the Botryosphaeriaceae family and Phaeomoniella chlamydospora, considered some of the most important causal agents for these diseases in Chile. In this study, we isolated 169 endophytic and 209 rhizospheric fungi from grapevines grown under organic and conventional farming in Chile. Multiple isolates of Chaetomium sp., Cladosporium sp., Clonostachys rosea, Epicoccum nigrum, Purpureocillium lilacinum, and Trichoderma sp. were evaluated for their potential of biocontrol activity against Diplodia seriata, Neofusicoccum parvum, and Pa. chlamydospora. Tests of antagonism were carried out using two dual-culture-plate methods with multiple media types, including agar containing grapevine wood extract to simulate in planta nutrient conditions. Significant pathogen growth inhibition was observed by all isolates tested. Clonostachys rosea showed 98.2% inhibition of all pathogens in the presence of grapevine wood extract. We observed 100% pathogen growth inhibition when autoclaved lignified grapevine shoots were pre-inoculated with either C. rosea strains or Trichoderma sp. Overall, these results show that C. rosea strains isolated from grapevines are promising biocontrol agents against GTDs.

Endophytic Fungi: From Symbiosis to Secondary Metabolite Communications or Vice Versa?

Endophytic fungi (EF) are a group of fascinating host-associated fungal communities that colonize the intercellular or intracellular spaces of host tissues, providing beneficial effects to their hosts while gaining advantages. In recent decades, accumulated research on endophytic fungi has revealed their biodiversity, wide-ranging ecological distribution, and multidimensional interactions with host plants and other microbiomes in the symbiotic continuum. In this review, we highlight the role of secondary metabolites (SMs) as effectors in these multidimensional interactions, and the biosynthesis of SMs in symbiosis via complex gene expression regulation mechanisms in the symbiotic continuum and via the mimicry or alteration of phytochemical production in host plants. Alternative biological applications of SMs in modern medicine, agriculture, and industry and their major classes are also discussed. This review recapitulates an introduction to the research background, progress, and prospects of endophytic biology, and discusses problems and substantive challenges that need further study.

Paecilomyces and Its Importance in the Biological Control of Agricultural Pests and Diseases

Incorporating beneficial microorganisms in crop production is the most promising strategy for maintaining agricultural productivity and reducing the use of inorganic fertilizers, herbicides, and pesticides. Numerous microorganisms have been described in the literature as biological control agents for pests and diseases, although some have not yet been commercialised due to their lack of viability or efficacy in different crops. Paecilomyces is a cosmopolitan fungus that is mainly known for its nematophagous capacity, but it has also been reported as an insect parasite and biological control agent of several fungi and phytopathogenic bacteria through different mechanisms of action. In addition, species of this genus have recently been described as biostimulants of plant growth and crop yield. This review includes all the information on the genus Paecilomyces as a biological control agent for pests and diseases. Its growth rate and high spore production rate in numerous substrates ensures the production of viable, affordable, and efficient commercial formulations for agricultural use.

Bioactive compounds guided diversity of endophytic fungi from Baliospermum montanum and their potential extracellular enzymes

Baliospermum montanum (Willd.) Muell. Arg, a medicinal plant distributed throughout India from Kashmir to peninsular-Indian region is extensively used to treat jaundice, asthma, and constipation. In the current study, 203 endophytic fungi representing twenty-nine species were isolated from tissues of B. montanum. The colonization and isolation rate of endophytes were higher in stem followed by seed, root, leaf and flower. The phytochemical analysis revealed 70% endophytic isolates showed alkaloids and flavonoids, 13% were positive for phenols, saponins and terpenoids. Further, these endophytes produced remarkable extracellular enzymes such as amylase, cellulase, phosphates, protease and lipase. The most promisive three endophytic fungi were identified by ITS region and secreted metabolites were identified by gas chromatography-mass spectrometry (GC-MS/MS). The GC-MS profile detected twenty-five bioactive compounds from ethyl acetate extracts. Among endophytic fungi, Trichoderma reesei isolated from flower exhibited nine bioactive compounds namely, 2-Cyclopentenone, 2-(4-chloroanilino)-4-piperidino, Oxime-methoxy-Phenyl, Methanamine N-hydroxy-N-methyl, Strychane, Cyclotetrasiloxane, Octamethyl and 1-Acetyl-20a-hydroxy-16-methylene. The endophyte, Aspergillus brasiliensis isolated from root and Fusarium oxysporum isolated from seed produced nine and seven bioactive compounds, respectively. Overall, a significant contribution of bioactive compounds was noticed from the diverse endophytic fungi associated with B. montanum and could be explored for development of novel drug with commercial values.

Identification and dereplication of endophytic Colletotrichum strains by MALDI TOF mass spectrometry and molecular networking

The chemical diversity of biologically active fungal strains from 42 Colletotrichum, isolated from leaves of the tropical palm species Astrocaryum sciophilum collected in pristine forests of French Guiana, was investigated. The collection was first classified based on protein fingerprints acquired by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) correlated with cytotoxicity. Liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS) data from ethyl acetate extracts were acquired and processed to generate a massive molecular network (MN) using the MetGem software. From five Colletotrichum strains producing cytotoxic specialized metabolites, we predicted the occurrence of peptide and cytochalasin analogues in four of them by MN, including a similar ion clusters in the MN algorithm provided by MetGem software. Chemoinformatics predictions were fully confirmed after isolation of three pentacyclopeptides (cyclo(Phe-Leu-Leu-Leu-Val), cyclo(Phe-Leu-Leu-Leu-Leu) and cyclo(Phe-Leu-Leu-Leu-Ile)) and two cytochalasins (cytochalasin C and cytochalasin D) exhibiting cytotoxicity at the micromolar concentration. Finally, the chemical study of the last active cytotoxic strain BSNB-0583 led to the isolation of four colletamides bearing an identical decadienamide chain.

Secondary Metabolites in the Treatment of Diabetes Mellitus: A Paradigm Shift

Diabetes mellitus (DM) is a chronic, polygenic and non-infectious group of diseases that occurs due to insulin resistance or its low production by the pancreas and is also associated with lifelong damage, dysfunction and collapse of various organs. Management of diabetes is quite complex having many bodily and emotional complications and warrants efficient measures for prevention and control of the same. As per the estimates of the current and future diabetes prevalence, around 425 million people were diabetic in 2017 which is anticipated to rise up to 629 million by 2045. Various studies have vaguely proven the fact that several vitamins, minerals, botanicals and secondary metabolites demonstrate hypoglycemic activity in vivo as well as in vitro. Flavonoids, anthocyanin, catechin, lipoic acid, coumarin metabolites, etc. derived from herbs were found to elicit a significant influence on diabetes. However, the prescription of herbal compounds depend on various factors, including the degree of diabetes progression, comorbidities, feasibility, economics as well as their ADR profile. For instance, cinnamon could be a more favorable choice for diabetic hypertensive patients. Diabecon®, Glyoherb® and Diabeta Plus® are some of the herbal products that had been launched in the market for the favorable or adjuvant therapy of diabetes. Moreover, Aloe vera leaf gel extract demonstrates significant activity in diabetes. The goal of this review was to inscribe various classes of secondary metabolites, in particular those obtained from plants, and their role in the treatment of DM. Recent advancements in recognizing the markers which can be employed for identifying altered metabolic pathways, biomarker discovery, limitations, metabolic markers of drug potency and off-label effects are also reviewed.

Endophytic fungus, Chaetomium globosum, associated with marine green alga, a new source of Chrysin

The marine ecosystem is an extraordinary reserve of pharmaceutically important, bioactive compounds even in this “synthetic age”. Marine algae-associated endophytic fungi have gained prominence as an important source of bioactive compounds. This study was conducted on secondary metabolites of Chaetomium globosum-associated with marine green alga Chaetomorpha media from the Konkan coastline, India. Its ethyl acetate extract (CGEE) exhibited an IC₅₀ value of 7.9 ± 0.1 µg/mL on MCF-7 cells. CGEE exhibited G2M phase cell cycle arrest, ROS production and MMP loss in MCF-7 cells. The myco-components in CGEE contributing to the cytotoxicity were found by Gas Chromatography/Mass Spectrometry analyses. Chrysin, a dihydroxyflavone was one of the forty-six myco-components which is commonly found in honey, propolis and passionflower extracts. The compound was isolated and characterized as fungal chrysin using HPLC, UV–Vis spectroscopy, LC–MS, IR and NMR analyses by comparing with standard chrysin. The purified compound exhibited an IC₅₀ value of 49.0 ± 0.6 µM while that of standard chrysin was 48.5 ± 1.6 µM in MCF-7 cells. It induced apoptosis, G1 phase cell cycle arrest, MMP loss, and ROS production. This is the first report of chrysin from an alternative source with opportunities for yield enhancement.

Bridging the Gap: Plant-Endophyte Interactions as a Roadmap to Understanding Small-Molecule Communication in Marine Microbiomes

Probing the composition of the microbiome and its association with health and disease states is more accessible than ever due to the rise of affordable sequencing technology. Despite advances in our ability to identify members of symbiont communities, untangling the chemical signaling that they use to communicate with host organisms remains challenging. In order to gain a greater mechanistic understanding of how the microbiome impacts health, and how chemical ecology can be leveraged to advance small-molecule drug discovery from microorganisms, the principals governing communication between host and symbiont must be elucidated. Herein, we review common modes of interkingdom small-molecule communication in terrestrial and marine environments, describe the differences between these environments, and detail the advantages and disadvantages for studies focused on the marine environment. Finally, we propose the use of plant-endophyte interactions as a stepping stone to a greater understanding of similar interactions in marine invertebrates, and ultimately in humans.

Discovery of New Secondary Metabolites by Epigenetic Regulation and NMR Comparison from the Plant Endophytic Fungus Monosporascus eutypoides

Overexpression of the histone acetyltransferase and the ¹H NMR spectroscopic experiments of the endophytic fungus Monosporascus eutypoides resulted in the isolation of two new compounds, monosporasols A (1) and B (2), and two known compounds, pestaloficin C (3) and arthrinone (4). Their planar structures and absolute configurations were determined by spectroscopic analysis including high resolution electrospray ionization mass spectroscopy (HRESIMS), one-dimensional (1D) and two-dimensional (2D) NMR, and calculated electronic circular dichroism data. Compounds 1–2 were screened in cytotoxic bioassays against HeLa, HCT-8, A549 and MCF-7 cells. Our work highlights the enormous potential of epigenetic manipulation along with the NMR comparison as an effective strategy for unlocking the chemical diversity encoded by fungal genomes.