Enhanced phenolic acids production in regenerated shoot cultures of Salvia virgata Jacq. after elicitation with Ag+ ions, methyl jasmonate and yeast extract

Phenolic acids, among the major secondary metabolites of Salvia species, are important bioactive phytochemicals, namely for their application in pharmaceutical industries. Biosynthesis of secondary metabolites, including phenolic acids in plant in vitro cultures is affected by biotic and abiotic elicitors, leading mostly to higher levels than in non-elicited ones. The present study was initially focused on achievement to a suitable procedure for direct multiple shoot regeneration on multinodal explants from 50 days old seedlings of Salvia virgata Jacq. on Murashige and Skoog (MS) solid media supplemented with different concentrations of 6-benzylaminopurine (BAP) and indole-3-acetic acid (IAA). Then, the effects of different concentrations of Ag+ ions, yeast extract (YE) and methyl jasmonate (MeJA) on total phenolic and flavonoid contents, as well as some phenolic acids were studied in the regenerated shoots after 1,3 and 5 days of elicitation in liquid free hormone MS medium. Based on the results, the maximum number of regenerated shoots (4.67) per responsive explant was obtained on MS medium containing 2 ppm BAP and 0.05 ppm IAA. As an effective abiotic elicitor, Ag+ ions could improve production of phenolic acids in the shoot cultures, while the highest content (26 mg/g DW) of rosmarinic acid (RA) was reported on day 5 after exposure of regenerated shoots to 2.5 ppm of Ag+ ions. Also, the highest contents of salvianolic acid A (Sal-A) (3.72 mg/g DW) and caffeic acid (CA) (35.5 mg/g DW) were found after elicitation of regenerated shoots with MeJA (11.2 ppm) on day 3 and Ag+ ions (2.5 ppm) on day 5, respectively. The results suggested that MeJA and Ag+ ions had the considerable ability to stimulate the production of valuable phenolic acids such as RA in the regenerated shoot cultures of S. virgata.