LDI MS Imaging of Plant Secondary Metabolites on Arabidopsis thaliana using Graphite and Silver as Matrixes

摘要

Colloidal graphite-assisted LDI (GALDI) MS imaging was introduced for imaging of small molecules such as phospholipids, cerebrosides, oligosaccharides, flavonoids, and other secondary metabolites with high spatial homogeneity due to the finely dispersed particles. Mass profiles and images of Arabidopsis thaliana were recorded directly from various plant surfaces and cross-sections. The main targeted metabolites were flavonoids and cuticular waxes, both of which are important in many aspects of functional genomics, proteomics, and metabolomics. Mass spectral profiles revealed tissue-specific accumulation of flavonoids in petals. The location and the degree of light-induced flavonoid accumulation in stem sections were successfully probed by GALDI MS. Colloidal-silver laser desorption/ionization (LDI) mass spectrometry (MS) was also employed to profile and image epicuticular wax metabolites in Arabidopsis flowers. With the ability of smallarea sampling and the excellent sensitivity, surface species of each flower part, carpels, petals, and sepals, were profiled for the first time.