Biocontrol potential of endophytic fungal-derived 3-Hydroxy-1,2-dimethyl-4 (1H)-pyridone against Venturia inaequalis.

Apple scab, caused by the pathogenic fungus Venturia inaequalis, is one of the most devastating diseases affecting apple production worldwide. Scab is primarily controlled through frequent applications of chemical fungicides, which are costly and pose significant risks to human health and the environment. In this context, the present investigation aimed to explore the diversity of endophytic fungi associated with apple cultivars, their antimicrobial potential and organic bioactive compounds, which could be used as bio-control agents against scab. 51 isolates of endophytic fungi were extracted from scab-resistant and susceptible apple cultivars. Their morphological and molecular examination resulted in the identification of 26 fungal strains. In vitro antifungal examination of identified fungal strains against V. inaequalis confirmed antagonistic activity of Fusarium oxysporum and F. solani. Bioactive compound responsible for antagonistic activity was purified and structurally characterized as 3-Hydroxy-1,2-dimethyl-4(1H)-pyridone (HDMP). Molecular docking studies of HDMP revealed favorable binding affinities toward the fungal target proteins, CYP51 and succinate dehydrogenase. Additionally, on-field application of F. oxysporum showed promising results in controlling apple scab. Overall, present study identified the antagonistic fungal strains from the apple cultivars and the bioactive compound HDMP, offering a sustainable and eco-friendly approach to apple scab management.