Hydrogen Peroxide and Nitric Oxide are Involved in Salicylic Acid-Induced Salvianolic Acid B Production in Salvia miltiorrhiza Cell Cultures

Hydrogen peroxide (H(2)O(2)) and nitric oxide (NO) are key signaling molecules in cells whose levels are increased in response to various stimuli and are involved in plant secondary metabolite synthesis. In this paper, the roles of H(2)O(2) and NO on salvianolic acid B (Sal B) production in salicylic acid (SA)-induced Salvia miltiorrhiza cell cultures were investigated. The results showed that H(2)O(2) could be significantly elicited by SA, even though IMD (an inhibitor of NADPH oxidase) or DMTU (a quencher of H(2)O(2)) were employed to inhibit or quench intracellular H(2)O(2). These elicited H(2)O(2) levels significantly increased NO production by 1.6- and 1.46 fold in IMD+SA and DMTU+SA treatments, respectively, and induced 4.58- and 4.85-fold Sal B accumulation, respectively. NO was also markedly elicited by SA, in which L-NNA (an inhibitor of NO synthase) and cPTIO (a quencher of NO) were used to inhibit or quench NO within cells, and the induced NO could significantly enhance H(2)O(2) production by 1.92- and 1.37-fold in L-NNA+SA and cPTIO+SA treatments, respectively, and 3.27- and 1.50-fold for Sal B accumulation, respectively. These results indicate that elicitation of SA for either H(2)O(2) or NO was independent, and the elicited H(2)O(2) or NO could act independently or synergistically to induce Sal B accumulation in SA-elicited cells.