Stimulation of the Salicylic Acid Pathway Aboveground Recruits Entomopathogenic Nematodes Belowground

PLoS One. 2016 May 3;11(5):e0154712. doi: 10.1371/journal.pone.0154712. eCollection 2016.

Abstract

Plant defense pathways play a critical role in mediating tritrophic interactions between plants, herbivores, and natural enemies. While the impact of plant defense pathway stimulation on natural enemies has been extensively explored aboveground, belowground ramifications of plant defense pathway stimulation are equally important in regulating subterranean pests and still require more attention. Here we investigate the effect of aboveground stimulation of the salicylic acid pathway through foliar application of the elicitor methyl salicylate on belowground recruitment of the entomopathogenic nematode, Steinernema diaprepesi. Also, we implicate a specific root-derived volatile that attracts S. diaprepesi belowground following aboveground plant stimulation by an elicitor. In four-choice olfactometer assays, citrus plants treated with foliar applications of methyl salicylate recruited S. diaprepesi in the absence of weevil feeding as compared with negative controls. Additionally, analysis of root volatile profiles of citrus plants receiving foliar application of methyl salicylate revealed production of d-limonene, which was absent in negative controls. The entomopathogenic nematode S. diaprepesi was recruited to d-limonene in two-choice olfactometer trials. These results reinforce the critical role of plant defense pathways in mediating tritrophic interactions, suggest a broad role for plant defense pathway signaling belowground, and hint at sophisticated plant responses to pest complexes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Assay
  • Food Chain
  • Herbivory / drug effects
  • Plant Roots / metabolism
  • Rhabditida / drug effects*
  • Salicylates / metabolism
  • Salicylates / pharmacology*
  • Volatile Organic Compounds / metabolism

Substances

  • Salicylates
  • Volatile Organic Compounds
  • methyl salicylate

Associated data

  • Dryad/10.5061/dryad.2b2b5

Grants and funding

The Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) program and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) provided financial support for the project through studentships and grants to CCF. MP was supported by a FAEPEX-PAPDIC grant from UNICAMP, and CNPq project 474449/2012-2.