Lipopolysaccharide Enhances Tanshinone Biosynthesis via a Ca-Dependent Manner in Hairy Roots.

Tanshinones, the major bioactive components in Bunge (Danshen), are synthesized via the mevalonic acid (MVA) pathway or the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway and the downstream biosynthesis pathway. In this study, the bacterial component lipopolysaccharide (LPS) was utilized as a novel elicitor to induce the wild type hairy roots of HPLC analysis revealed that LPS treatment resulted in a significant accumulation of cryptotanshinone (CT) and dihydrotanshinone I (DTI). qRT-PCR analysis confirmed that biosynthesis genes such as and from the MVA pathway, and from the MEP pathway, and , and from the downstream pathway were markedly upregulated by LPS in a time-dependent manner. Furthermore, transcription factors WRKY1 and WRKY2, which can activate the expression of , and , were also increased by LPS. Since Ca signaling is essential for the LPS-triggered immune response, Ca channel blocker LaCl and CaM antagonist W-7 were used to investigate the role of Ca signaling in tanshinone biosynthesis. HPLC analysis demonstrated that both LaCl and W-7 diminished LPS-induced tanshinone accumulation. The downstream biosynthesis genes including and were especially regulated by Ca signaling. To summarize, LPS enhances tanshinone biosynthesis through WRKY1- and WRKY2-regulated pathways relying on Ca signaling. Ca signal transduction plays a key role in regulating tanshinone biosynthesis in .