title: Tracing hidden herbivores: time-resolved non-invasive analysis of belowground volatiles by proton-transfer-reaction mass spectrometry (PTR-MS).
abstract: Root herbivores are notoriously difficult to study, as they feed hidden in the soil. However, root herbivores may be traced by analyzing specific volatile organic compounds (VOCs) that are produced by damaged roots. These VOCs not only support parasitoids in the localization of their host, but also may help scientists study belowground plant-herbivore interactions. Herbivore-induced VOCs are usually analyzed by gas-chromatography mass spectrometry (GC-MS), but with this off-line method, the gases of interest need to be preconcentrated, and destructive sampling is required to assess the level of damage to the roots. In contrast to this, proton-transfer-reaction mass spectrometry (PTR-MS) is a very sensitive on-line, non-invasive method. PTR-MS already has been successfully applied to analyze VOCs produced by aboveground (infested) plant parts. In this review, we provide a brief overview of PTR-MS and illustrate how this technology can be applied to detect specific root-herbivore induced VOCs from Brassica plants. We also specify the advantages and disadvantages of PTR-MS analyses and new technological developments to overcome their limitations.
authors.affiliation: Department of Ecogenomics, Institute for Water and Wetland Research (IWWR), Radboud University, PO Box 9010, 6500 GL, Nijmegen, The Netherlands. h.danner@science.ru.nl
authors.forename: Holger
authors.initials: H
authors.lastname: Danner
authors.forename: Devasena
authors.initials: D
authors.lastname: Samudrala
authors.forename: Simona M
authors.initials: SM
authors.lastname: Cristescu
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Van Dam
mesh_terms: D000818:Animals; D001937:Brassica / Q000737:chemistry / Q000469:parasitology*; D060434:Herbivory; D006790:Host-Parasite Interactions; D007313:Insecta / Q000502:physiology*; D013058:Mass Spectrometry / Q000379:methods*; D018521:Plant Physiological Phenomena; D018517:Plant Roots / Q000737:chemistry / Q000469:parasitology*; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000378:metabolism
chemical_list: D055549:Volatile Organic Compounds