Trichoderma asperellum strains confer tomato protection and induce its defense-related genes against the Fusarium wilt pathogen

Fusarium wilt of tomato (FW) caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a major challenge for tomato production worldwide. For sustainable management of FW, the potential of five strains of Trichoderma asperellum was evaluated under greenhouse conditions. The results indicated that FOL infected plants treated with T. asperellum strains significantly reduced disease incidence and severity compared with FOL-only infected plants. The reduction of wilt disease on plants treated with T. asperellum strains was accompanied by a significant reduction in FOL populations in tomato stems and rhizosphere. Moreover, the application of T. asperellum promoted tomato plant growth irrespective of the presence or absence of FOL. Two strains of T. asperellum (TS-12 and TS-39) that showed the best performance in minimizing disease development and increases in plant growth parameters were selected for elucidating their ability in triggering tomato defense mechanisms. The expression levels of defense-related genes, chitinase ( SlChi3 ), β-1,3-glucanase ( SlGluA ) and PR-1 ( SlPR-1a ) were significantly increased in the stems and roots of Trichoderma treated, FOL infected plants, compared with FOL-only infected ones. These results indicate that the application of T. asperellum strains TS-12 and TS-39 can be used as an alternative strategy to manage FW through their antagonistic activities and abilities to induce systemic resistance.