Abstract
<jats:p>Endophytic fungi associated with medicinal plants are increasingly recognized as potential sources of biological control agents for plant disease management. In this study, endophytic fungi were isolated from Strychnos lucida, an indigenous medicinal plant from Timor Island, and their antagonistic activity was evaluated in vitro. Eight fungal endophytes were obtained from root, stem, and leaf tissues and were preliminarily characterized based on morphological features, whereas species-level identification using ITS rDNA sequencing was conducted for the two most antagonistic isolates. All isolates significantly reduced pathogen growth (P < 0.05), with inhibition values ranging from 40.30–84.98% against Fusarium oxysporum and 41.03–94.70% against Colletotrichum capsici. Two isolates, S1-SL and S3-SL, showed high inhibitory activity (>80%). Molecular analysis based on ITS rDNA sequences identified these isolates as Fusarium cassiae and Trichoderma asperellum, respectively. To the best of our knowledge, the occurrence of F. cassiae as an endophyte associated with S. lucida has not been previously reported, suggesting a possible new host–endophyte association. Microscopic observations revealed mycoparasitic interactions characterized by hyphal coiling, penetration, and lysis of pathogen hyphae. These findings indicate that endophytic fungi from S. lucida represent promising candidates for biological control of plant pathogens, although further greenhouse and field studies are needed to validate their effectiveness under tropical dryland conditions. Keywords: Antifungal activity, biological control, medicinal plant-associated endophytes, plant microbe interaction, tropical dryland ecosystem.</jats:p>