Abstract:[Background] Melatonin is a small-molecule biogenic amine ubiquitous in animals and plants, which promotes the growth and environmental adaptation of organisms. Trichoderma act as important biocontrol strains and engineering strains of industrial products, which can produce diverse secondary metabolites. [Objective] Since the melatonin synthesis in Trichoderma strains remains unclear, we constructed a Trichoderma viride strain capable of synthesizing melatonin and characterized its physiological properties. [Methods] In this study, the genes hAANAT encoding human alkylamine N-acetyltransferase and hASMT encoding human acetylserotonin O-methyltransferase were heterologously expressed in T. viride Tv-1511. The yield of melatonin synthesized by the engineered strain was determined by high performance liquid chromatography (HPLC). Furthermore, the growth, stress resistance, and growth-promoting and biocontrol abilities of the engineered strain were determined by biochemical methods. [Results] A melatonin-producing strain of T. viride was obtained, which had better growth and sporulation characteristics, stronger stress tolerance, stronger antagonism to pathogens, and higher plant growth-promoting ability than the start strain. [Conclusion] Melatonin plays a positive role in the growth and stress resistance of T. viride. It is of great significance to construct the Trichoderma strains with melatonin-synthesizing ability by genetic modification.
