Untargeted Metabolomics of Plant Leaf Tissues

Untargeted metabolomics is a useful approach for the simultaneous analysis of a vast array of compounds from a single extract. Metabolomic profiling is the relative multi-parallel quantification of a mixture of low molecular weight compounds, or classes of compounds, and it is most often performed by using ultra performance liquid chromatography (UPLC) coupled with mass spectrometry (MS). Being an extension of the classical targeted methods, this approach allows a broader view of the main biochemical events within a particular sample. This chapter exemplifies and provides experimental details on the basic steps to perform a non-targeted metabolomic analysis on plant leaf tissues: sample collection and homogenization, extraction of metabolites, raw data acquisition, and processing into formats for data mining and informatics. In particular, the approach was applied to two spring wheat varieties with different level of drought tolerance (Kavir, drought-resistant; Bahar, drought-sensitive) developed by the CIMMYT (International Center for the Improvement of Corn and Wheat).