Effect of yeast elicitor on the secondary metabolism of Ti-transformed Salvia miltiorrhiza cell suspension cultures

Abstract

Salvia miltiorrhiza contains two groups of biologically active secondary metabolites termed phenolic compounds (e.g. rosmarinic acid) and tanshinones (e.g. cryptotanshinone). Their roles in plant defense responses were examined using a simplified system consisting of a yeast elicitor and a Ti C58 transformed S. miltiorrhiza cell line. Both dosage and time course studies were carried out on the effects of yeast elicitor on the formation of rosmarinic acid and cryptotanshinone. It was found that the yeast elicitor reduced the constituent level of rosmarinic acid (from ca. 5% to ca. 3.0% of dry cell weight) whereas the level of cryptotanshinone was enhanced greatly (from a negligible amount to ca. 20 mg/l). These results suggest that in S. miltiorrhiza, rosmarinic acid and cryptotanshinone may take part in plant passive and active defense responses, respectively, against pathogen attack. Cryptotanshinone was identified as a phytoalexin in S. miltiorrhiza for the first time. Results of the treatment of cell cultures with 2-aminoindan-2-phosphonic acid, a highly specific and potent inhibitor of phenylalanine ammonia-lyase (EC 4.3.1.5), indicated that this compound did not inhibit yeast elicitor induced tanshinone formation, but did inhibit rosmarinic acid biosynthesis.