The Transcriptional Regulator TRG1 Plays a Role in Regulating Peptaibol Biosynthesis in Trichoderma longibrachiatum

Trichoderma species are valued as potent biocontrol agents, largely attributable to their production of peptaibols, structurally diverse secondary metabolites known for antibacterial activity, induction of apoptosis, and enhancement of plant disease resistance. To better understand the regulatory mechanisms underlying peptaibol synthesis, this study characterized the transcription regulator gene TRG1, identified within a non-ribosomal peptide synthetase (NRPS) gene cluster in T. longibrachiatum SMF2. A ΔTRG1 knockout mutant was successfully generated via homologous recombination. Phenotypic comparison with the wild-type strain revealed that the ΔTRG1 mutant maintained comparable growth rate, colony morphology, and sporulation capacity. However, it showed significantly reduced antagonistic activity against the phytopathogen Botrytis cinerea, as well as diminished efficacy in controlling gray mold on detached rose leaves. High-performance liquid chromatography (HPLC) analysis provided direct evidence that peptaibol yield in the mutant decreased by approximately 2.5-fold relative to the wild type. Collectively, these results demonstrate that TRG1 acts as a key positive transcriptional regulator essential for high-level peptaibol biosynthesis, likely through modulation of NRPS gene expression. Thus, TRG1 represents a promising molecular target for bioengineering approaches aimed at improving the biocontrol performance of Trichoderma strains.