Isolation and identification of Trichoderma strains, and antifungal effects and solid-state fermentation recipe optimization from Xinjiang wild fruit forest

Abstract:

[Background] The Xinjiang wild apple are suffering serious diseases, and Trichoderma is an important plant disease biocontrol fungus, so it can be used to prevent and control wild apple diseases in Xinjiang. [Objective] In order to isolate and identify the Trichoderma isolates from wild fruit forests in Xinjiang, determine their antifungal ability against two pathogens of wild apples (Malus sieversii), and provide the biocontrol fungal resources for the preparation of “Special Trichoderma Biofertilizer for Xinjiang wild apple”. [Methods] Trichoderma strains were isolated by plate dilution method from the rhizosphere of 4 herbaceous plants in Xinjiang wild fruit forest. Species identification was performed by morphology and molecular biology, and the antifungal ability of Trichoderma isolates was tested by plate confrontation tests, and the solid-state fermentation formula of Trichoderma strains was optimized. [Results] The results show that 2 Trichoderma species (total 42 strains) were isolated, including 34 T. asperellum isolates and 8 T. atroviride isolates. The inhibitory rates of T. asperellum T01 (TasT01) against Colletotrichum gloeosporioides (Cgl) and Alternaria alternaria f. sp. mali (Aal) were 58.60% and 57.14%, respectively; and the inhibitory rates of T. atroviride (TatT35) to Cgl and Aal were 43.86% and 36.90%, respectively. Further microscopic observation showed that TasT01 could inhibit the growth of both pathogens through hypha coiling. The solid-state fermentation formula of TatT35 strain was 90% rice husk, 10% wheat bran, 0.5% (NH₄)₂SO₄. And the spore concentration could reach 1.0×10⁸/g spores. [Conclusion] TasT01 and TatT35 have good inhibitory effects on the two pathogens of Xinjiang wild apple, and the spore concentration significantly increased after the solid-state fermentation formula was optimized. The results provide a reference for biological control of fungal diseases of Xinjiang wild apple.