We strive to find new analytical approaches to apply mass spectrometry technology to solve various biological problems. In a DOE-supported project, we develop high spatial resolution MALDI imaging technology to map plant metabolites at a single-cell level. Many techniques are available to visualize macromolecules such as DNA, RNA, and proteins; however, such tools are scarce for small molecules. MALDI-MS imaging does not require labeling for high-sensitivity identification of known and unknown molecules, and it allows profiling of many metabolites at once. Our technique reveals metabolic biology in unprecedented details in highly complex multicellular plant organisms.