A transcriptional regulator gene TRG1 of Trichoderma longibrachiatum is involved in the regulation of peptaibols synthesis

Trichoderma species are recognized for their robust biocontrol capacity, primarily due to the production of peptaibols, potent secondary metabolites that exhibit antibacterial properties, induce cell apoptosis, and enhance plant disease resistance. To elucidate the regulatory mechanism of peptaibol synthesis, we investigated the role of a transcription regulator gene TRG1 (designated as TLTRG1), which we identified within a non-ribosomal peptide synthetase (NRPS) gene cluster of T. longibrachiatum SMF2. We successfully created a{Delta} TRG1 gene knockout mutantusing homologous recombination. Phenotypic analysis indicated that the{Delta} TRG1 mutant maintained wild-type growth rate, colony morphology, and spore production. However,{Delta} TRG1 exhibited a significantly reduced inhibition rate against the plant pathogen Botrytis cinerea and a lower efficacy in controlling gray mold on detached rose leaves. High-performance liquid chromatography (HPLC) analysis provided direct molecular evidence, showing that peptaibol production in the mutant was 2.5 times lower than that of the wild-type strain. These findings conclusively establish that TRG1 functions as a key positive transcriptional regulator essential for high-yield peptaibol biosynthesis by modulating NRPS gene expression. This gene represents a critical molecular target for bioengineering strategies aimed at enhancing the biocontrol efficacy of Trichoderma strains. The Importance sectionTrichoderma species are known to produce peptaibols, which exhibit antibacterial properties, induce cell apoptosis, and enhance plant disease resistance. However, the mechanisms underlying the biosynthesis and regulation of peptaibols remain unclear. In this study, we investigated the role of a transcription regulator gene located within a non-ribosomal peptide synthetase (NRPS) gene cluster of T. longibrachiatum SMF2, which we designated as TLTRG1 (TRG1). Phenotypic analysis indicated the inhibition rate of {Delta}TRG1 against Botrytis cinerea and its effectiveness in controlling gray mold were significantly reduced compared to the WT strain. High-performance liquid chromatography (HPLC) analysis revealed that the production of peptaibols in the mutant was significantly decreased. These findings suggest that the TRG1 gene may play a crucial role in regulating the expression of NRPS genes, thereby affecting the biosynthesis of peptaibols. Therefore, it can be concluded that the gene TRG1 is a molecular target for bioengineering strains with enhanced biocontrol efficacy.