Functional Divergence of Diterpene Syntheses in the Medicinal Plant Salvia miltiorrhiza1[OPEN]

• Published in: Plant physiology (Bethesda) Vol. 169; no. 3; pp. 1607 - 1618
• Main Authors: Cui, Guanghong, Duan, Lixin, Jin, Baolong, Qian, Jun, Xue, Zheyong, Shen, Guoan, Snyder, John Hugh, Song, Jingyuan, Chen, Shilin, Huang, Luqi, Peters, Reuben J., Qi, Xiaoquan
• Format: Journal Article
• Language: English
• Published: American Society of Plant Biologists 15.06.2015
• Series: Focus on Metabolism
• Subjects: s - Focus Issue
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.15.00695

Positive selection and the divergent evolution by exon/intron patterns driving the fast divergence of copalyl diphosphate synthases underlie the biosynthesis of specialized diterpenes. The medicinal plant Salvia miltiorrhiza produces various tanshinone diterpenoids that have pharmacological activities such as vasorelaxation against ischemia reperfusion injury and antiarrhythmic effects. Their biosynthesis is initiated from the general diterpenoid precursor ( E , E , E )-geranylgeranyl diphosphate by sequential reactions catalyzed by copalyl diphosphate synthase ( CPS ) and kaurene synthase-like cyclases. Here, we report characterization of these enzymatic families from S. miltiorrhiza , which has led to the identification of unique pathways, including roles for separate CPS s in tanshinone production in roots versus aerial tissues (SmCPS1 and SmCPS2, respectively) as well as the unique production of ent -13-epi-manoyl oxide by SmCPS4 and S. miltiorrhiza kaurene synthase-like2 in floral sepals. The conserved SmCPS5 is involved in gibberellin plant hormone biosynthesis. Down-regulation of SmCPS1 by RNA interference resulted in substantial reduction of tanshinones, and metabolomics analysis revealed 21 potential intermediates, indicating a complex network for tanshinone metabolism defined by certain key biosynthetic steps. Notably, the correlation between conservation pattern and stereochemical product outcome of the CPS s observed here suggests a degree of correlation that, especially when combined with the identity of certain key residues, may be predictive. Accordingly, this study provides molecular insights into the evolutionary diversification of functional diterpenoids in plants.