Enhanced antagonistic potential of gamma-irradiated Trichoderma spp. against Phytophthora capsici : An in vitro study

Enhancing the biocontrol efficacy of microorganisms is a crucial element in advancing sustainable agricultural practices, particularly in the management of soilborne fungal phytopathogens. Among the various methods employed to augment the effectiveness of biocontrol agents, gamma radiation has emerged as a particularly promising approach due to its ability to induce genetic mutations that can enhance antagonistic properties. In the present study, an efficient gamma irradiation technique was employed to induce genetic modifications in three biocontrol agents: Trichoderma guizhouense , T. koningiopsis , and T. asperellum. The efficacy of these genetically altered strains was then evaluated against the pathogen Phytophthora capsici. Mutant isolates were generated through exposure to varying doses of gamma radiation and were initially screened based on their growth rates. These were subsequently subjected to a series of in vitro antagonistic tests. The results demonstrated that five selected mutants Ta 200-1, Ta 250-2, Tg 200-1, Tg 250-2, and Ta 150-3 exhibited significantly enhanced antagonistic potential compared to their parent strains. Importantly, these mutants retained their improved traits even after ten rounds of subculturing, with growth inhibition percentages ranging from 72.11% to 68.11%. The findings from the in vitro antagonistic studies suggest that gamma irradiation represents an effective strategy for enhancing the antagonistic capabilities of Trichoderma species, thereby contributing to the development of more robust biocontrol agents in plant health management.