Smoke-Isolated Karrikins Stimulated Tanshinones Biosynthesis in Salvia miltiorrhiza through Endogenous Nitric Oxide and Jasmonic Acid.

Although smoke-isolated karrikins (KAR₁) could regulate secondary metabolism in medicinal plants, the signal transduction mechanism has not been reported. This study highlights the influence of KAR₁ on tanshinone I (T-I) production in Salvia miltiorrhiza and the involved signal molecules. Results showed KAR₁-induced generation of nitric oxide (NO), jasmonic acid (JA) and T-I in S. miltiorrhiza hairy root. KAR₁-induced increase of T-I was suppressed by NO-specific scavenger (cPTIO) and NOS inhibitors (PBITU); JA synthesis inhibitor (SHAM) and JA synthesis inhibitor (PrGall), which indicated that NO and JA play essential roles in KAR₁-induced T-I. NO inhibitors inhibited KAR₁-induced generation of NO and JA, suggesting NO was located upstream of JA signal pathway. NO-induced T-I production was inhibited by SHAM and PrGall, implying JA participated in transmitting signal NO to T-I accumulation. In other words, NO mediated the KAR₁-induced T-I production through a JA-dependent signaling pathway. The results helped us understand the signal transduction mechanism involved in KAR₁-induced T-I production and provided helpful information for the production of S. miltiorrhiza hairy root.