In vitro Evaluation of Three Unexploited Fungi for Their Biocontrol Potential against Selected Phytopathogenic Fungi

Background: The increasing incidence of fungal phytopathogens poses a serious threat to the balance of our ecosystem. While chemical fungicides are commonly used for disease control, their excessive application leads to environmental contamination, the development of resistant pathogen strains and the disruption of beneficial soil microbiota. This has intensified the search for eco-friendly and sustainable biocontrol alternatives. Methods: In the present study, phytopathogenic fungi Penicillium citrinum, Bipolaris sorokiniana and Alternaria alternata were isolated from diseased Morus alba and Melia azedarach. Simultaneously, rare and underexplored non-pathogenic fungi, Purpureocillium sodanum, Talaromyces pinophilus and Aspergillus ochraceopetaliformis were isolated from the rhizospheric soil of healthy Morus alba trees growing near the Bhakhra riverbank. Fungal identification was conducted based on colony morphology, microscopic features and molecular analysis using 18S rRNA sequencing. The antagonistic potential of these non-pathogenic isolates was evaluated in vitro using dual culture assays against the phytopathogenic fungi. Result: Dual culture assays revealed significant antagonistic effects, with inhibition percentages ranging from 33.3% to 85.7%. Among the isolates, P. sodanum showed the highest inhibition (85.7%) against A. alternata, surpassing the commonly reported efficacy of standard Trichoderma strains. Enzymatic assays further indicated the production of hydrolytic enzymes, suggesting multiple mechanisms of pathogen suppression. This study presents Purpureocillium sodanum as a highly effective in vitro antagonist with superior inhibition compared to standard Trichoderma strains. These findings support its potential as a novel, eco-friendly biocontrol agent and warrant further investigation for broader agricultural applications.