NMR-based metabolomic analysis of plants

Nuclear magnetic resonance (NMR)-based metabolomics has many applications in plant science. Metabolomics can be used in functional genomics and to differentiate plants from different origin, or after different treatments. In this protocol, the following steps of plant metabolomics using NMR spectroscopy are described: sample preparation (freeze drying followed by extraction by ultrasonication with 1:1 CD(3)OD:KH(2)PO(4) buffer in D(2)O), NMR analysis (standard (1)H, J-resolved, (1)H-(1)H correlation spectroscopy (COSY) and heteronuclear multiple bond correlation (HMBC)) and chemometric methods. The main advantage of NMR metabolomic analysis is the possibility of identifying metabolites by comparing NMR data with references or by structure elucidation using two-dimensional NMR. This protocol is particularly suited for the analysis of secondary metabolites such as phenolic compounds (usually abundant in plants), and for primary metabolites (e.g., sugars and amino acids). This procedure is rapid; it takes not more than 30 min for sample preparation (multiple parallel) and a further 10 min for NMR spectrum acquisition.