Genetic diversity and biocontrol efficacy of indigenous Trichoderma isolates against Fusarium wilt of pepper

Trichoderma species are recognized as biocontrol agents with great potential in inhibiting fungal pathogens that cause significant crop losses. In this study, 15 Trichoderma isolates were collected from various Egyptian locations. Internal transcribed spacer sequencing revealed four different Trichoderma species; Trichoderma harzianum, Trichoderma asperellum, Trichoderma longibrachiatum, and Trichoderma viride. The antagonistic activity of Trichoderma isolates against Fusarium oxysporum f. sp. capsici was evaluated in vitro. The effect of Trichoderma isolates on pepper growth plants in the presence of F. oxysporum was studied in planta. The inhibition of pathogen mycelial growth in vitro ranged between 35.71% and 85.75%. The isolates Ta3 and Tl had the highest antagonistic ability in vitro against F. oxysporum f. sp. capsici. However, Th7 and Th6 of T. harzianum isolates showed the highest values of disease severity reduction under greenhouse conditions. The genetic diversity of the Trichoderma isolates (Ta1, Ta2, Th1, Th2, Th3, Th4, Th5, and Tv) was investigated on the basis of ISSR and SCoT markers. SCoT primers generated a total of 28 bands, out of which 14 (50%) were polymorphic. ISSR primers gave 32 bands, and 11 of these bands (34.37%) were polymorphic.