Metabolites of Tilletia laevis Suppress Fusarium solani Growth Through Metabolic Disruption and Oxidative Stress Responses

Fusarium solani is a major soil-borne pathogen responsible for root rot diseases, posing a significant threat to agricultural productivity. The development of environmentally sustainable alternatives to chemical fungicides is therefore urgently needed. This study evaluated the antifungal activity of fermentation broths and extracellular metabolites derived from Tilletia laevis fungi at different developmental stages against F. solani under in vitro conditions. Six test agents, including carbendazim (one positive fungicide control), caffeic acid, phenylacetylglycine, and 6-hydroxypyridine-2-carboxylic acid (candidate bioactive metabolites), were evaluated for mycelial growth inhibition, EC50 values, and physiological responses. All treatments exhibited concentration-dependent inhibitory effects, with carbendazim showing the highest activity (EC50 = 21.26 mg L−1). Among the metabolites, 6-hydroxypyridine-2-carboxylic acid and phenylacetylglycine demonstrated notable antifungal efficacy, particularly at higher concentrations. Fermentation broths from the promycelial stage showed stronger inhibition than those from the teliospore stage, indicating stage-specific metabolite activity. Biochemical analyses of F. solani mycelia revealed significant changes in soluble protein, soluble sugar, and antioxidant enzyme activities (SOD and POD), suggesting that antifungal effects are mediated through metabolic disruption and oxidative stress. These findings highlight the potential of T. laevis-derived metabolites as eco-friendly biofungicides and provide a theoretical basis for sustainable management of soil-borne diseases. Further studies are required to identify active compounds and validate their efficacy under field conditions.