Expression profiles of rosmarinic acid biosynthesis genes in two Salvia miltiorrhiza lines with differing water-soluble phenolic contents

Phenolic acids are among the important bioactive compounds found in Salvia miltiorrhiza Bunge. Rosmarinic acid (RA) has been identified as the core structure of most phenolic acids in this widely useful herb. This work describes a comparative analysis of the expression patterns of RA biosynthetic genes in relation to different accumulation patterns of phenolic acid contents in two danshen genotypes, DS1 (S. miltiorrhiza) and DS2 (S. miltiorrhiza f. alba C.Y.Li). Quantitative real-time PCR (qRT-PCR) showed that the transcriptional expression levels of most of the genes were significantly higher in DS1 than in DS2. The results indicated that the higher RA accumulation observed in DS1 might be a result of the up-regulation of several co-expressed genes in this metabolic pathway. SmPAL, SmC4H, Sm4CL and SmHPPD may serve as key genes in the regulation of RA accumulation in DS1. SmTAT might play a more important role in regulating the content of salvianolic acid B (SAB). Overall, our results provide new information on the expression profiles of biosynthetic genes in connection with phenolic acid accumulation at the molecular level in two danshen germplasm selections.