Endophytic fungi isolated from coffee plants promote Arabidopsis thaliana growth and suppress soil-borne fungal pathogens.

Endophytic beneficial microorganisms are widely used in agriculture for promoting plant growth and enhancing plant defense mechanisms. This study aimed to characterize endophytic fungi isolated from the roots of coffee plants cultivated in organic agroforestry systems and evaluate their potential as biocontrol agents against fungal pathogens, as well as their ability to promote plant growth. Biocontrol activity was assessed using in vitro dual-culture assays on potato dextrose agar, measuring the inhibition of pathogen growth. Plant growth promotion was evaluated by co-cultivating Arabidopsis thaliana seedlings with fungal isolates on Murashige and Skoog medium. Isolates were further subjected to both qualitative and quantitative biochemical characterization. A total of 18 endophytic fungal strains were identified and classified in five genera: Colletotrichum, Fusarium, Simplicillium, Lasiodiplodia and Trichoderma. Among these, ten Trichoderma isolates demonstrated strong antagonistic activity against selected fungal pathogens and significantly enhanced the growth of Arabidopsis seedlings in vitro. These beneficial effects were associated with the production of siderophores and indole-3-acetic acid, as well as the apparent nitrogen availability -- likely mediated through interactions with nitrogen-fixing bacteria.