Molecular cloning of SoHPPR encoding a hydroxyphenylpyruvate reductase, and its expression in cell suspension cultures of Salvia officinalis

Rosmarinic acid (RA) is a naturally-derived compound present in medicinal plants, herbs and spices, and is well-known for its antioxidant, antibacterial and medicinal properties. It has been recently considered for use as a food preservative, nutraceutical, and for medicinal purposes. Undifferentiated cells (callus and cell suspensions) cultured in vitro are often used for the production of secondary metabolites, and for identifying biosynthetic pathways. In this work Salvia officinalis L. (common sage) cell suspension cultures were established, and a specific cell line was selected for the high antioxidant capacity of its methanolic extract, which was characterized by a high content of RA. Scavenger activity (DPPH test) and total RA content were evaluated during cell growth. Gene coding for Hydroxyphenylpyruvate reductase, the key-enzyme responsible for the RA metabolic biosynthesis, was cloned from common sage (SoHPPR). Its transcript expression level was monitored during cell suspension cultures, and showed a relationship with scavenger activity and RA yield. Our results suggest the potential use of this gene as a marker and target for the modulation of RA production in controlled conditions.