[Comparative metabolomics reveals the mechanism for the high GA₄ production in <i>Gibberella fujikuroi</i> CGMCC 17793].

With unique advantages, gibberellin GA₄ has broad application prospects. To explore the regulatory mechanism for the biosynthesis of GA₄, we combined liquid chromatography-mass spectrometry (LC-MS)-based metabolomics with principal component analysis (principal component analysis, PCA) and partial least squares-discriminant analysis (PLS-DA) to screen and identify the differential metabolites between the GA₄-producing strains S (industrial high-yield strain CGMCC 17793) and wild-type strain Y (NRRL 13620) of <i>Gibberella fujikuroi</i> fermented for the same time and the differential metabolites of strain S fermented for different time periods. KEGG and MBROLE 2.0 were used to analyze the metabolic pathways involving the differential metabolites. The results showed that compared with strain Y, strain S significantly upregulated and downregulated 107 and 66, 136 and 47, and 94 and 65 metabolites on days 3, 6, and 9, respectively. Compared with that on day 3 of fermentation, strain S upregulated 29 metabolites and downregulated 40 metabolites on day 6 and upregulated 52 metabolites and downregulated 67 metabolites on day 9. The differential metabolites between strain S and strain Y after fermentation for the same time were mainly enriched in amino acid metabolism, tricarboxylic acid (TCA) cycle, and terpenoid biosynthesis. The differential metabolites of strain S after fermentation for different time periods were mainly enriched in amino acid and sugar metabolism pathways. Pathway annotation results indicated that strain S increased the production of acetyl-CoA by promoting amino acid and sugar metabolism and TCA cycle, thereby enhancing the mevalonic acid pathway and increasing the content of isopentenyl pyrophosphate (IPP), a precursor for the synthesis of terpenoids, which ultimately led to increased GA₄ production. This study explored the metabolic rules of <i>Gibberella fujikuroi</i> GA₄, providing a theoretical basis for regulating <i>Gibberella fujikuroi</i> to improve GA₄ production.