Functional characterization of transcription factors GlZn₂Cys₆_82 regulating ganoderic acids in Ganoderma lucidum

Ganoderic acids (GAs), the major lanostane-type triterpenoids in Ganoderma lucidum (G. lucidum), possess diverse pharmacological activities but are produced at low levels, limiting their applications. Transcriptional regulation of GA biosynthesis remains poorly understood. In this study, we functionally characterized the GlZn₂Cys₆-type transcription factor GlZn₂Cys₆_82 and elucidated its role in GA biosynthesis. Overexpression of GlZn₂Cys₆_82 significantly increased total triterpenoids during the mycelial stage and promoted the accumulation of multiple individual GAs at the primordia stage, whereas silencing resulted in markedly reduced GA levels. qRT-PCR analyses revealed that GlZn₂Cys₆_82 positively regulates key biosynthetic genes, including HMGR, SQS, and LS, with SQS showing the strongest transcriptional induction. Subcellular localization assays demonstrated that GlZn₂Cys₆_82 is a nuclear protein, and yeast one-hybrid analyses confirmed its direct binding to the SQS promoter, establishing SQS as a downstream target. Comparative transcriptome profiling further showed that GlZn₂Cys₆_82 modulates genes involved in the mevalonate pathway and secondary metabolism. Collectively, our findings identify GlZn₂Cys₆_82 as a positive regulator of GA biosynthesis and provide a basis for metabolic engineering to increase GA production.