Variation of phenolic compounds and expression of phenylpropanoid biosynthetic genes in two medicinal and aromatic species of Salvia subg. Perovskia

Salvia yangii B.T.Drew (Perovskia atriplicifolia) and S. abrotanoides (Kar.) Sytsma (P. abrotanoides) are both rich in bioactive polyphenols and terpenoids and thus widely used in traditional medicine in Iran, Afghanistan and Pakistan. Targeted comparison of metabolic profiles of these two species revealed significant differences despite their close taxonomic relationship.

To get a better understanding into mechanisms regulating the biosynthesis of phenolics, roots and leaves of S. yangii and S. abrotanoides collected in three growth stages during the vegetative season were analyzed for non-volatile phenolics profile and key biosynthetic gene expression. The LC- MS analysis showed that in leaves non-volatile phenylpropanoids were exclusively represented by rosmarinic acid while in roots RA and its two derivatives: salviaflaside and salvianolic acid L were found. The accumulation of RA and its derivatives was observed in both – leaf and root tissue, during vegetation season.

To enable monitoring the expression of phenylpropanoid biosynthetic genes, partial cds of phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate:CoA ligase (4CL), tyrosine aminotransferase (TAT), hydroxyphenylpyruvate reductase (HPPR) and two isoforms of rosmarinic acid synthase (RAS1 and RAS2) in S. yangii and S. abrotanoides were amplified and sequenced. Quantitative real-time PCR analysis was used to investigate the expression pattern of amplified biosynthetic genes. We used a comparative analysis of phytochemical and gene expression profiling to elucidate transcriptional mechanisms underpinning biosynthesis of non-volatile phenylpropanoids in S. yangii and S. abrotanoides during a vegetative season.