Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/17/2002
Publication Date: 10/1/2002
Citation: SIRVENT, T., GIBSON, D.M. INDUCTION OF HYPERICINS AND HYPERFORIN IN HYPERICUM PERFORATUM L. IN RESPONSE TO BIOTIC AND ABIOTIC ELICITORS. PHYSIOLOGICAL AND MOLECULAR PLANT PATHOLOGY. 2002. v. 60. p. 311-320. Interpretive Summary: Hypericum perforatum L. (family Hypericaceae), commonly called St. John's wort, is considered to be an important dietary supplement, with worldwide sales of over $500 million. The bulk of St. John's wort is supplied from wild-harvested materials, generating growing concerns in terms of loss of biodiversity, variability in quality, and adulteration and contamination issues. The aim of the present study was to determine whether the active biological principles, hypericins and hyperforin, are part of the plant defense system of St. John's wort. We found that levels of both types of compounds were elevated when plants were infected with a host-specific plant pathogen or when plants were treated with chemicals known to induce plant defense responses. Since the pricing of St. John's wort is based on the concentration of hypericins and hyperforin, this study may be useful in identifying ways to boost the production of the active ingredients.
Technical Abstract: Hypericum perforatum L. produces both hyperforins, a family of antimicrobial acylphloroglucinols, and hypericins, a family of phototoxic anthraquinones exhibiting anti-microbial, anti-viral, and anti-herbivore properties in vitro. To determine whether these secondary metabolites are part of the plant defense system, we used meristem cultures to assess the effects of exposure to exogenous application of the abiotic elicitors, methyl jasmonate and salicylic acid. Levels of hypericins in plant tissue increased in response to both elicitor treatments; total hypericin levels increased as much as 3.3 times control levels when treated with 200 uM methyl jasmonate treatment for 14 days. Increased hyperforin concentrations were detected when plantlets were treated with 1 mM salicylic acid or 50 uM methyl jasmonate. For assessing responses to a biotic elicitor, greenhouse-grown plant materials were inoculated with the plant pathogen, Colletotrichum gloeosporioides. Levels of hypericins increased twice as much as the control when inoculated with 1 x 104 spores/mL; higher doses of spores overwhelmed the plant defenses. The elevation of hypericins and hyperforin in response to abiotic and biotic elicitors suggests that these secondary metabolites are components in the inducible plant defense responses of H. perforatum.