TcMYB1, TcMYB4, and TcMYB8 participate in the regulation of lignan biosynthesis in Taiwania cryptomerioides Hayata

Taiwania (Taiwania cryptomerioides Hayata) is a conifer species that is rich in bioactive secondary metabolites. Lignans, which are the major extracts, are especially important, but the biosynthetic gene regulation and downstream biosynthesis pathways remain unclear. In a previous study, we identified three pinoresinol-lariciresinol reductase (PLR) genes in Taiwanina, and in the present study, the regulation of these PLR genes was investigated. Through next-generation transcriptome sequencing, gene co-expression network analysis was performed to predict the relationship between putative transcription factor genes and upstream biosynthetic genes. Three MYB genes were identified as putative lignan biosynthetic regulators and named TcMYB1, TcMYB4, and TcMYB8. The gene expression of TcMYBs and TcPLRs was further confirmed with real-time PCR. Finally, an Agrobacteria-mediated transient overexpression experiment was conducted, and the activation of proTcPLR3::YFP by TcMYBs suggested that TcMYB1, TcMYB4, and TcMYB8 are biosynthetic regulators of lignan. These lignan regulators can be used in further research and applied to achieve a higher lignan content.