Fungal endophytes isolated from wild tomato produced metabolites with antifungal activity against phytopathogenic fungi

Fungal endophytes are known to produce diverse metabolites with multiple applications. In this study, endophytic fungi isolated from Solanum pimpinellifolium, a wild and underutilized tomato, were evaluated for their antifungal potential against some phytopathogenic fungi namely Alternaria alternata, Fusarium oxysporum and Colletotrichum gloeosporioides. Among all isolates, an endophytic fungus identified as Penicillium sumatraense showed the prominent antifungal against all test pathogens. The metabolites of the fungus showed 56.92 %, mycelial growth inhibition against A. alternata. SEM study revealed that the fungal metabolites significantly affect the hyphal structure of the pathogen and showed rupturing and shrinkage of the fungal mycelia. The main metabolite present in the organic extract of the endophyte was purified by chromatographic methods and identified as (-)-(S)-curvularin by comparing its spectroscopic 1H NMR and ESI-MS and optical rotation data with those reported in literature. In-vitro study of (-)-(S)-curvularin against A. alternata showed significant fungistatic activity at concentration of 31.25 µg ml−1 with growth inhibition of 29.96 %. In-silico molecular docking study of (-)-(S)-curvularin was undertaken to observe the binding interaction with 3HNR enzyme of the targeted pathogen, A. alternata. The study indicated that this compound has greater binding affinity with receptor protein of the pathogen than commercially available fungicide indicating as a superior antifungal agent. Hence, exploration of endophytes from wild crop plants can unveil novel bioactive compounds that could be a better alternative than chemical fungicides to control plant pathogens. Our findings also agree with the assumption that special traits like disease resistance nature of wild crops may be due to its associated endophytes.