Fungal endophytes isolated from Protium heptaphyllum and Trattinnickia rhoifolia as antagonists of Fusarium oxysporum

Chaetomugilins and Chaetoviridins—Promising Natural Metabolites: Structures, Separation, Characterization, Biosynthesis, Bioactivities, Molecular Docking and Molecular Dynamics

Fungi are recognized as luxuriant metabolic artists that generate propitious biometabolites. Historically, fungal metabolites have largely been investigated as leads for various therapeutic agents. Chaetomugilins and the closely related chaetoviridins are fungal metabolites, and each has an oxygenated bicyclic pyranoquinone core. They are mainly produced by various Chaetomaceae species. These metabolites display unique chemical features and diversified bioactivities. The current review gives an overview of research about fungal chaetomugilins and chaetoviridins regarding their structures, separation, characterization, biosynthesis, and bioactivities. Additionally, their antiviral potential towards the SARS-CoV-2 protease was evaluated using docking studies and molecular dynamics (MD) simulations. We report on the docking and predictive binding energy estimations using reported crystal structures of the main protease (PDB ID: 6M2N, 6W81, and 7K0f) at variable resolutions—i.e., 2.20, 1.55, and 1.65 Å, respectively. Chaetovirdin D (43) exhibited highly negative docking scores of −7.944, −8.141, and −6.615 kcal/mol, when complexed with 6M2N, 6W81, and 7K0f, respectively. The reference inhibitors exhibited the following scores: −5.377, −6.995, and −8.159 kcal/mol, when complexed with 6M2N, 6W81, and 7K0f, respectively. By using molecular dynamics simulations, chaetovirdin D’s stability in complexes with the viral protease was analyzed, and it was found to be stable over the course of 100 ns.

Identification of Antagonistic Compounds between the Palm Tree Xylariale Endophytic Fungi and the Phytopathogen Fusarium oxysporum

To discover microorganisms that naturally possess chemical weapons against the phytopathogen Fusarium oxysporum, the biological and chemical diversity of plant leaf endophytes was investigated. Endophytes were isolated from the palm tree Astrocaryum sciophyllum collected in pristine forests of French Guiana. Several Xylariaceae inhibited the growth of F. oxysporum and were further explored. Antifungal specialized metabolites were isolated from the Xylariaceae BSNB-0294 strain in confrontation with the phytopathogen and led to the identification of undescribed compounds, i.e., two depsipeptides named xylariaceins, two metabolites containing a 3-imidazolinone moiety, and four new compounds including a nitro-phenylpropanamide and three phenylalanine analogues named xylariains A-D. In parallel, the chemical investigation of the phytopathogen during the coculture led to the identification of an unknown compound, which we named focicin. The production of focicin was exacerbated during the competition. Matrix-assisted laser desorption/ionization coupled to time-of-flight mass spectometry (MALDI-TOF MS) imaging of the competition between BSNB-0294 (endophytic strain) and F. oxysporum f.sp. ciceris (phytopathogen) highlighted time-dependent chemical interactions between the two microorganisms.

Exploring the potentialities of beneficial endophytes for improved plant growth

Pathogen affects plant growth, host health and productivity. Endophytes, presumed to live inside the plant tissues, might be helpful in sustaining the future of agriculture. Although recent studies have proven that endophytes can be pathogenic, commensal, non-pathogenic, and/or beneficial, this review will focus on the beneficial category only. Beneficial endophytes produce a number of compounds which are useful for protecting plants from environmental conditions, enhancing plant growth and sustainability, while living conveniently inside the hosts. The population of endophytes is majorly controlled by location, and climatic conditions where the host plant grows. Often the most frequently isolated endophytes from the tissues of the plant are fungi, but sometimes greater numbers of bacteria are isolated. Beneficial endophytes stand a chance to replace the synthetic chemicals currently being used for plant growth promotion if carefully explored by researchers and embraced by policymakers. However, the roles of endophytes in plant growth improvement and their behavior in the host plant have not been fully understood. This review presents the current development of research into beneficial endophytes and their effect in improving plant growth.