Untargeted Metabolomics of Arabidopsis Stomatal Immunity.

Although untargeted metabolomic approaches hold great promise for global identification of low molecular weight metabolites in biological samples, deep coverage and confident identification of the metabolites remains challenging due to the great diversity and number of chemical structures, especially in plants. Additionally, there is a need to employ a cell-specific research approach to many physiological and biological responses to specific environmental stimuli. Here, we report an untargeted metabolomic method using Arabidopsis thaliana guard cell samples during response to systemic signals of pathogen attack. We employed a new Acquire X MSn data acquisition technology, which uses an iterative fragmentation process to increase level-2 identification of unknown metabolites. We were able to increase the number of identified metabolites and thus the metabolome coverage in Arabidopsis guard cells. This method can be applied to studying metabolomes of other cell types and tissues.