Characterization and expression profiling of tyrosine aminotransferase gene from Salvia miltiorrhiza (Dan-shen) in rosmarinic acid biosynthesis pathway.

A novel tyrosine aminotransferase gene (designated as SmTAT) involved in rosmarinic acid biosynthesis pathway is cloned from Salvia miltiorrhiza Bung. The full-length cDNA of SmTAT is 1,603 bp long with an open reading frame (ORF) of 1,233 bp encoding a polypeptide of 411 amino acid residues. The deduced amino acid sequence of the SmTAT gene shared high homology with other known TATs. Analysis of SmTAT genomic DNA reveals that it contains 6 exons, 5 introns. The analysis of SmTAT promoter region and terminator region was also presented. Semi-quantitative RT-PCR analysis reveals that the constitutive expression of SmTAT in stem is much higher than that in root, leaf. Further expression analysis reveals that the signaling components of defense/stress pathways, such as methyl jasmonate (MeJA), abscisic acid (ABA), salicylic acid (SA) and ultraviolet-B radiation (UV-B), up-regulate the SmTAT transcript levels over the control. This study provides useful information for further studying this gene and its function in rosmarinic acid biosynthetic pathway in S. miltiorrhiza, the roots of which so-called ''Danshen'' possess many pharmaceutical properties for human health.