Elicitation of secondary metabolism in Hypericum perforatum by rhizosphere bacteria and derived elicitors in seedlings and shoot cultures

Context: Hypericum perforatum L. (Guttiferae) appears as an alternative treatment to mild and moderate depression and been traditionally used as a health enhancer based on the phytochemicals hyperforin and hypericin. However, field grown medicinal plants show variable levels of phytopharmaceuticals depending on environmental conditions. Elicitation is a good strategy to trigger secondary metabolism.Objective: This study explored the ability of 6 rhizobacterial strains to trigger secondary metabolism in H. perforatum seedlings and molecular elicitors from the most effective strain N5.18 were tested in shoot cultures.Materials and methods: Hypericin and pseudohypericin were determined on seedlings and shoot cultures by HPLC. Three putative elicitors from bacterial culture media were assayed in three different concentrations.Results: Strain N5.18 significantly increased hypericin up to 1.2 ppm and pseudohypericin up to 3.4 ppm, over controls (0.3 and 2.5 ppm, respectively) when delivered to seedlings. In sho...