Taxonomy, metabolite diversity and antimicrobial activity of Tectaria coadunata (J.Sm.) C.Chr. fungal endophytes

Abstract

Endophytic fungi profoundly influence plant physiology and chemical ecology, yet their integrated functional roles remain underexplored, especially in ferns. Here, we reveal that Tectaria coadunata (J.Sm.) C.Chr. harbours a taxonomically rich and metabolically active endophytic mycobiome comprising ten genera with distinct ecological and evolutionary lineages. Morphological diagnostics combined with multilocus phylogenetics resolved all isolates with high confidence, delineating well-supported clades across Aspergillus, Calonectria, Diaporthe, Fusarium, Macrophomina, Neurospora, Nigrospora, Penicillium, Rhizoctonia, and Xylaria. LC-Q-TOF-MS/MS profiling uncovered extensive metabolic cross-communication between the host plant and endophytes. Nine phytochemicals previously attributed to T. coadunata were also present in fungal endophytes, while eleven additional metabolites, including potent polyketides, mellein, and mycotoxins were exclusively endophytic. Multivariate and network analyses revealed distinct chemical profiles among different fungal isolates and coordinated biosynthetic modules, underscoring functional heterogeneity of the community. All isolates exhibited antimicrobial activity, but Xylaria grammica had the least minimum inhibitory concentration of 15.63 µg/mL against Bacillus subtilis and methicillin-resistant Staphylococcus aureus. This pronounced activity, coupled with its broad-spectrum inhibition, positions X. grammica as a promising reservoir of pharmaceutically relevant molecules. Collectively, our findings establish T. coadunata as a reservoir of phylogenetically diverse, chemically productive, and bioactive endophytes. These combined taxonomic, metabolomic, and functional insights into endophytes from T. coadunata open new avenues for potential applications across various fields.