Metabolomic differentiation of Brassica rapa following herbivory by different insect instars using two-dimensional nuclear magnetic resonance spectroscopy.
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.
Widarto
Heru Tri
HT
Division of Pharmacognosy, Section Metabolomics, Institute of Biology, Leiden University, 2300RA, Leiden, The Netherlands.
Van Der Meijden
Ed
E
Lefeber
Alfons W M
AW
Erkelens
Cornelis
C
Kim
Hye Kyong
HK
Choi
Young Hae
YH
Verpoorte
Robert
R
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