SmCPK20 phosphorylates SmWRKY2 to regulate jasmonate-mediated tanshinone synthesis in Salvia miltiorrhiza

Jasmonates (JAs) are vital to plant defense and stress adaptation. In Salvia miltiorrhiza, JA significantly promotes tanshinone accumulation, a class of bioactive diterpenoids. Although transcriptional regulation of JA signaling is well characterized, the post-translational mechanisms governing JA-mediated tanshinone biosynthesis remain poorly understood. Here, we identify SmWRKY2 as a critical regulator of JA-induced tanshinone accumulation, which interacts with SmCPK20. SmCPK20 positively regulates JA-induced tanshinone accumulation. JA signaling activates SmCPK20, promoting phosphorylation of SmWRKY2 at Thr-256. This phosphorylation event significantly enhances SmWRKY2's binding to the SmCPS1 promoter and its transcriptional activation capacity, thereby promoting tanshinone accumulation. Furthermore, SmWRKY2 interacts with the JA signaling repressor SmJAZ3. SmJAZ3 inhibits the SmWRKY2-SmCPK20 interaction in the absence of JA. JA-triggered degradation of SmJAZ3 releases SmWRKY2, enabling SmCPK20-mediated phosphorylation and promoting tanshinone biosynthesis. Collectively, our results demonstrate that JA and Ca²⁺ signaling pathways cooperate to regulate plant secondary metabolism.