The Jasmonate-Responsive SmMPK3-SmWRKY33 Module Positively Regulates Tanshinone Biosynthesis in Salvia miltiorrhiza.

Tanshinones, the major bioactive diterpenes in Salvia miltiorrhiza Bunge, are widely used to treat cardiovascular and cerebrovascular diseases. While jasmonates (JAs) are known to modulate tanshinones accumulation, the molecular link between JA signalling and tanshinone biosynthesis remains unclear. Here, we identify SmWRKY33, a JA-responsive WRKY transcription factor, as a key regulator of tanshinone biosynthesis through multiomic and genetic analyses. SmWRKY33 is highly expressed in the roots of S. miltiorrhiza. SmWRKY33 directly binds to the promoters of SmCPS1, SmKSL1, SmCYP76AH3, SmCYP71D373 and Sm2-ODD14, activating their transcription and promoting tanshinones accumulation. Notably, SmWRKY33 interacts with SmJAZ8, a JA signalling repressor, which suppresses its transcriptional activity on tanshinone biosynthetic genes. Additionally, SmMPK3 is responsive to JA signaling and functions as a positive regulator of tanshinone biosynthesis in S. miltiorrhiza. Furthermore, SmMPK3 directly associates with and phosphorylates SmWRKY33, a modification that enhances its transcriptional activity and DNA-binding capacity. Collectively, our findings elucidate how JA signalling integrates with MAPK phosphorylation to regulate specialised metabolism and provide molecular targets for metabolic engineering to enhance tanshinones production in S. miltiorrhiza.