Screening of Native Trichoderma Isolates for Volatile Organic Compound Production and Antagonism Against Pythium spp.

Abstract

Screening of native Trichoderma isolates for volatile organic compound (VOC) production and antagonism against Pythium spp. was conducted to identify effective biocontrol candidates for suppression of soil-borne pathogens. Soil samples from diverse agricultural fields were used to isolate indigenous Trichoderma strains, which were subsequently characterized for growth behavior, sporulation capacity, and VOC emission profiles under in vitro conditions. Dual culture assays and sealed-plate techniques were employed to evaluate antagonistic activity against Pythium spp., focusing on mycelial inhibition, hyphal interaction, and suppression of pathogen growth through volatile-mediated effects. Results revealed significant variability among isolates in both VOC production and antagonistic potential. Highly effective isolates exhibited strong inhibition of Pythium mycelial growth, accompanied by marked morphological distortion and reduced sporulation of the pathogen. VOCs produced by selected Trichoderma strains played a critical role in pathogen suppression, indicating non-contact inhibitory mechanisms. Microscopic observations confirmed coiling, penetration, and lysis of pathogen hyphae in direct interaction assays, suggesting multiple modes of antagonism including competition, mycoparasitism, and antibiosis. The study highlights the importance of native Trichoderma diversity as a valuable resource for sustainable disease management. These findings support the development of environmentally friendly biocontrol strategies targeting Pythium-induced diseases in agricultural systems through the use of highly antagonistic VOC-producing Trichoderma strains.