Karrikins-induced accumulation of Salvianolic acid B is mediated by calcium–calmodulin, brassinolide and jasmonic acid in Salvia miltiorrhiza

Abstract

The effects of smoke-derived karrikins (KAR1) on the contents of endogenous signal molecules including (Ca2+)–calmodulin (CaM), brassinolide (BL) and Jasmonic acid (JA) and secondary metabolite Salvianolic acid B (SAB) in Salvia miltiorrhiza hairy roots have been investigated. The results showed that the burst of Ca2+–CaM, BL and JA were early responses of S. miltiorrhiza responding to KAR1. Treatments with exogenous CaCl2 and BL dramatically improved the level of JA, while JA inhibitor salicylhydroxamic acid/n-propylgallate (SHAM/PrGall) did not influence levels of Ca2+ and BL in S. miltiorrhiza hairy roots. Furthermore, pretreatments with the Ca2+ channel blockers LaCl3 (La3+) and Verapamil (VERA), and CaM antagonists [N-(6-amin-ohexyl)-5-chloro-1-naphthalene sulfonamide hydrochloride] (W7) and trifluoperazine (TFP) substantially reduced KAR1-induced BL accumulation, while the Ca2+ production induced by KAR1 was reduced by BL inhibitor Brassinazole (BRz). It suggested that Ca2+ and BL seem to have a parallel relationship and act as upstream signaling molecules to medicate the production of JA. The inhibitory effects of VERA, W7, BRz and SHAM toward SAB production induced by the KAR1 could be reversed by exogenous jasmonate methyl (JAMe), while the exogenous CaCl2 and BL had no similar effects. It proved that Ca2+–CaM, BL mediated the KAR1-induced increase of SAB dependent on the generation of JA in S. miltiorrhiza hairy roots. This study help us understand the regulatory mechanism of Ca2+–CaM, BL, JA on KAR1-induced accumulation of SAB in S. miltiorrhiza hairy roots.