The endophytic fungus Discosia artocreas DY-17 suppresses postharvest gray mold in tomato through direct antagonism and host defense-associated responses

Gray mold, caused by Botrytis cinerea , significantly reduces postharvest tomato quality, and biological control offers a safer and more sustainable alternative to synthetic fungicides. However, the postharvest biocontrol potential of Discosia artocreas remains largely unexplored. In this study, the endophytic fungal strain DY-17 was isolated from the leaves of Drynaria roosii Nakaike and identified as D. artocreas . Dual-culture assays showed that DY-17 inhibited B. cinerea mycelial growth by 83.40 ± 0.61% and exhibited broad-spectrum antifungal activity against 12 additional plant-pathogenic fungi. Scanning electron microscopy revealed that DY-17 caused B. cinerea mycelial abnormalities and inhibited spore production. In vivo experiments confirmed that DY-17 pretreatment effectively reduced gray mold development, decreased B. cinerea accumulation in tomato fruit, and reduced lesion area by 88.0% at 120 h. Whole-genome analysis identified diverse predicted biosynthetic gene clusters, including nonribosomal peptide synthetase, polyketide synthase, terpene, siderophore, and indole clusters, indicating the genetic potential of DY-17 to produce bioactive secondary metabolites. Furthermore, DY-17 pretreatment increased phenylalanine ammonia-lyase, polyphenol oxidase, β-1,3-glucanase, and chitinase activities, and enhanced the expression of defense-related genes SlPR2 and SlPR3 in tomato fruit. Combined transcriptome and metabolome analyses revealed DY-17-associated changes in plant hormone signal transduction, flavonoid and phenylpropanoid metabolism, redox-related metabolism, and organic acid and fatty acid metabolism in tomato. JA/ET-related signaling was a prominent component of these defense-associated responses, while additional hormone-related pathways were also altered. In conclusion, D. artocreas DY-17 suppresses postharvest gray mold through direct antagonism of B. cinerea combined with host defense-associated responses. This study provides a foundation for developing fungal biocontrol agents for the sustainable management of postharvest diseases.