title: Metabolomic differentiation of Brassica rapa following herbivory by different insect instars using two-dimensional nuclear magnetic resonance spectroscopy.
abstract: The metabolic alterations of Brassica rapa (L.) leaves attacked by larvae of the specialist Plutella xylostella L. (Lepidoptera: Yponomeutidae) and the generalist Spodoptera exigua Hubner (Lepidoptera: Noctuidae) were investigated with nuclear magnetic resonance (NMR) spectroscopy, followed by a multivariate data analysis. The principal component analysis (PCA) of (1)H NMR spectra showed that metabolic changes in B. rapa leaves induced by the 2nd and the 4th instars were different from each other. However, the congestion of the one-dimensional (1)H NMR spectrum made it difficult to identify discriminating metabolites. To overcome the spectral complexity, several two-dimensional NMR techniques were applied. Of those evaluated, J-resolved spectroscopy, which affords an additional coupling constant, provided a wide range of structure information on differentiating the metabolites. Based on the J-resolved spectra combined with PCA, the major signals contributing to the discrimination were alanine, threonine, glucose, sucrose, feruloyl malate, sinapoyl malate, and gluconapin.
authors.affiliation: Division of Pharmacognosy, Section Metabolomics, Institute of Biology, Leiden University, 2300RA, Leiden, The Netherlands.
authors.forename: Heru Tri
authors.initials: HT
authors.lastname: Widarto
authors.forename: Ed
authors.initials: E
authors.lastname: Van Der Meijden
authors.forename: Alfons W M
authors.initials: AW
authors.lastname: Lefeber
authors.forename: Cornelis
authors.initials: C
authors.lastname: Erkelens
authors.forename: Hye Kyong
authors.initials: HK
authors.lastname: Kim
authors.forename: Young Hae
authors.initials: YH
authors.lastname: Choi
authors.forename: Robert
authors.initials: R
authors.lastname: Verpoorte
mesh_terms: D000818:Animals; D029741:Brassica rapa / Q000378:metabolism* / Q000469:parasitology; D007814:Larva / Q000502:physiology*; D007915:Lepidoptera / Q000254:growth & development / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D018515:Plant Leaves / Q000378:metabolism; D013045:Species Specificity