Chapter One - High-Resolution 1H-NMR Spectroscopy and Beyond to Explore Plant Metabolome

Abstract

Abstract During the past decade, metabolomics has become a crucial functional genomic tool. Tremendous advances in instrumentation, automation, data handling capabilities and statistical analyses have boosted this discipline. Today, most investigations of the plant metabolome tend to be based on either nuclear magnetic resonance (NMR) spectrometry or mass spectrometry (MS), with or without hyphenation with chromatography or capillary electrophoresis. Although less sensitive than MS, NMR provides a powerful complementary technique for the identification and quantification of metabolites in plant extracts. High-resolution one-dimensional (1D) proton NMR spectroscopy (1H-NMR) is a robust technique, highly reproducible, non-selective and non-destructive, able to produce structural information and quantitative data. In this review, we highlight important technical prere-quisites for sample preparation, acquisition parameters, as well as recent developments in NMR and resources available for spectra annotation, which are necessary to pursue plant 1H-NMR metabolomics studies. 1H-NMR is the ideal nucleus for most metabolomics studies. On the one hand, multivariate analysis of unassigned 1H-NMR spectra (concept of metabolite fingerprinting) is used to compare the overall metabolic composition of plant extracts. On the other hand, identification and quantification of 20–60 metabolites (concept of metabolite profiling) in unfractionated extracts are used to spot the major metabolites in plant extracts. Both strategies generate key information concerning the plant metabolome, but in an incomplete way. Several applications of NMR fingerprinting and profiling approaches are presented from the characterization of food or medicinal plants to plant functional genomics, showing the key role that 1H-NMR plays in data provision for food and plant sciences. The future challenges for 1H-NMR metabolomics are linked with the developments in NMR spectroscopy technology that provide improvement in signal detection and quantitation and also the facility to use shared databases.