Functional characterization of PcMYB25, a candidate regulator of Patchouli alcohol biosynthesis in Pogostemon cablin,...

Plant hormones often cause changes in secondary metabolites. Patchouli alcohol (PA) is a bioactive compound of the medicinal plant Pogostemon cablin. Similar to other secondary metabolites, its synthesis is also regulated by transcription factors. While the PA biosynthetic pathway has been characterized, its regulatory mechanisms remain incompletely understood.

Transcriptome analysis revealed that exogenous hormone application significantly altered the transcriptional landscape of Pogostemon cablin, particularly affecting genes involved in terpenoid metabolism. Through weighted gene co-expression network analysis (WGCNA), we identified the R2R3-MYB transcription factor gene PcMYB25 as a key candidate regulator. Transient overexpression analysis showed that overexpression of PcMYB25 significantly upregulated PcPTS expression and select upstream MVA pathway genes, and increased PA content by 85% compared to empty vector controls. In addition, yeast one-hybrid assays confirmed that PcMYB25 binds to the PcPTS promoter, and transcriptional activation assays demonstrated its strong transactivation activity.

We conclude that exogenous hormone treatment triggers an extensive transcriptional response in patchouli, and integrated co-expression analysis identifies PcMYB25 as a candidate regulatory factor involved in plant hormone signaling and the accumulation of PcPTS-derived PA and sesquiterpenoid compounds. These findings not only provide new insights into the transcriptional regulation of PA biosynthesis, but also lay the foundation for further genetic engineering strategies for PA production.