New insights into rosmarinic acid biosynthesis based on molecular studies

•Rosmarinic acid is an important plant secondary metabolite.•This review summarizes the knowledge on the genetic background of rosmarinic acid.•PAL, TAT, C4H, 4CL, HPPR and RAS to varying degree but all affect the rosmarinic acid formation. The knowledge about rosmarinic acid has been growing continuously since it has been first elucidated. It has various types of biological activities and it proved to be an excellent therapeutic agent. Large amount of rosmarinic acid is found in several plant species. Rosmarinic acid is one of the metabolites, which is actually produced by in vitro cultures, not only under experimental conditions, but also in large-scale. The biosynthetic pathway of rosmarinic acid is explored, and many of its influencing factors have been studied thoroughly. In the last decade, the number of transcriptome level studies connected to its biosynthesis has grown, focusing mostly on the identification and expression of the related genes in different species. Moreover, studies were published on gene regulation, enzyme activity in correlation to rosmarinic acid production, regulatory elements affecting the gene expression, and on combinatorial biosynthesis. The aim of this review is to summarize the results of the recent molecular genetics studies in relation to rosmarinic acid production in plants.