PatSWC4, a methyl jasmonate-responsive MYB (v-myb avian myeloblastosis viral oncogene homolog)-related transcription factor, positively regulates patchoulol biosynthesis in Pogostemon cablin

Abstract

Patchoulol, the major active ingredient in Pogostemon cablin (Blanco) Benth., has considerable clinical and industrial value. A number of genes that participate in the patchoulol biosynthesis pathway have been identified; however, little is known about the transcription factors involved in regulating patchoulol synthesis. In this study, PatSWC4, a homologous protein of Arabidopsis SWC4 belonging to the MYB (v-myb avian myeloblastosis viral oncogene homolog)-related transcription factor family, was identified and characterized. Subcellular localization showed that PatSWC4 protein localized in the nucleus. The highest expression level of PatSWC4 gene was found in old leaves of P. cablin and it was significantly induced by methyl jasmonate (MeJA). Additionally, yeast one-hybrid (Y1H) and dual-luciferase (dual-LUC) assays revealed that PatSWC4 could bind to the promoter of PatPTS gene to increase its transcriptional activity. Yeast two-hybrid (Y2H) assays also confirmed the interaction between PatSWC4 and PatJAZ4 proteins, indicating that PatSWC4 might function in the JA response network. Moreover, transient overexpression of PatSWC4 gene in P. cablin leaves markedly increased the production of patchoulol, and qRT-PCR analysis further revealed that genes in the patchoulol biosynthesis pathway were significantly upregulated at the transcriptional level. Ultimately, we proposed a work model depicting how JA signaling regulates PatPTS via the interaction between PatSWC4 and PatJAZ4, thereby regulating the biosynthesis of patchoulol. Our findings not only help to elucidate the regulatory mechanism governing JA-induced patchoulol biosynthesis, but also lay a foundation for future studies on improving patchoulol production through genetic and metabolic engineering.