Application potential of three marine Trichoderma spp.

Abstract:

[Objective] To explore the application potential of three marine Trichoderma spp. as biocontrol agents and bio-fertilizer. [Methods] Three Trichoderma spp. with high antimicrobial activity and spore germination were selected by isolating, screening and mutagenesis. Several indicators related with application potential of these strains were tested. Sporulation capacity was measured after optimizing culture medium, temperature and initial pH. Antimicrobial activity was evaluated based on inhibition spectrum, superparasitism and related antifungal genes. Special culture method was used to determine the secretion of cellulase, phytase and siderophore, and the ability to release phosphorus and potassium. High performance liquid chromatography was used to quantify indole-3-acetic acid production. [Results] We obtained three Trichoderma spp. with the spore germinations of 3.45×10⁸, 3.10×10⁸ and 2.55×10⁸ CFU/cm², respectively. Moreover, these mutants formed chlamydospores, and strain XG20-1 had the highest chlamydospore germination of 3.56×10⁸ CFU/mL. All three strains showed a broad inhibition spectrum against 6 fungal phytopathogen and the superparasitism to Alternaria solani. Moreover, Tex1, Nag1 and Eg1 genes were found in all strains, with cellulose, phytase and siderophore detected. Indole-3-acetic acid productions in three strains were 2.61, 1.57 and 1.92 mg/L, respectively, and all three strains had the capacity of releasing phosphorus and potassium. [Conclusion] Three Trichoderma spp. had high antimicrobial activities against plant pathogenic fungi through integrated mechanism, high spore-bearing yields and growth-promoting effects on plants, which showed their potential application as biocontrol agents and bio-fertilizer.

Key words:marine Trichoderma spp.;pathogen inhibition and related gene;a variety of enzyme activity;P-releasing and K-releasing