Accession-Level Differentiation of Urushiol Levels, and Identification of Cardanols in Nascent Emerged Poison Ivy Seedlings

Molecules. 2019 Nov 20;24(23):4213. doi: 10.3390/molecules24234213.

Abstract

Poison ivy (Toxicodendron radicans (L.) Kuntze) shows accession-level differentiation in a variety of morphometric traits, suggesting local adaptation. To investigate whether the presumed defense compound urushiol also demonstrates accession-level accumulation differences, in vitro nascent germinated poison ivy seedlings from geographically isolated populations were germinated in vitro and then assayed for known urushiol congener accumulation levels. Significant accession-level differences in the accumulation levels of total C15- and C17-, total C15-, total C17-, specific C15 congeners, and specific C17 congeners of urushiol were identified. In addition, hereto novel C15- and C17-urushiol isomers were identified as well. Cardanols are assumed to be the penultimate metabolites giving rise to urushiols, but this assumption was not previously empirically validated. C15-cardanol congeners and isomers corresponding to expected substrates needed to produce the observed C15-urushiol congeners and isomers were identified in the same poison ivy seedling extracts. Total C15-cardanol and C15-cardanol congeners also showed significant accession-level differences. Based on the observed C15-cardanol congeners in poison ivy, the penultimate step in urushiol biosynthesis was proposed to be a cardanol-specific hydroxylase activity.

Keywords: Toxicodendron radicans; and cardanol hydroxylase; cardanol; poison ivy; urushiol.

MeSH terms

  • Phenols* / chemistry
  • Phenols* / metabolism
  • Plant Extracts / chemistry*
  • Seedlings* / chemistry
  • Seedlings* / metabolism
  • Toxicodendron* / chemistry
  • Toxicodendron* / metabolism

Substances

  • Phenols
  • Plant Extracts
  • cardanol