Cell wall degradation by glucanase activity: Trichoderma pleuroticola and Pythium ultimum interaction

Abstract

During mycoparasitism, Trichoderma fungi secrete various cellulases and glucanases. This study aimed to investigate the role of endo-glucanase and exo-glucanase enzymes in the biological control of the soil-borne pathogen Pythium ultimum by Trichoderma. To enhance enzyme production, Trichoderma spores were irradiated with a γ-ray dose of 250 Gy, and the resulting mutants were compared to the wild-type strain. Using proteomics and cellulase enzyme assays, we assessed the antagonistic activity of wild-type and mutant Trichoderma isolates against P. ultimum in dual culture tests. After 48 h of fermentation, cellulase activity in the culture supernatants was measured using different substrates. Extracellular proteins were characterized using SDS-PAGE and two-dimensional electrophoresis to identify the most prominent catalytic components involved in enzyme production. The Trichoderma isolates (wild-type and mutant) were identified as Trichoderma pleuroticola based on the sequence analysis of the ITS1-5.8 S-ITS2 and TEF-1α regions. The mutant isolates, particularly NAS109-M21, demonstrated significantly increased enzyme activity compared to the wild-type. NAS109-M21 exhibited 2.5 times higher exo-glucanase activity and three times higher endoglucanase activity. In dual culture assays, this mutant strain showed a 65 % reduction in P. ultimum growth, which is five times greater than the wild-type. Furthermore, SDS-PAGE and 2D electrophoresis revealed sharper bands for endo-glucanase, exoglucanase, and β-glucosidase in the mutant strain. These findings suggest that gamma irradiation can induce mutations in T. pleuroticola, leading to enhanced enzyme production and improved biocontrol potential against Pythium ultimum in soil.