Metabolome analysis of Biosynthetic mutants reveals a diversity of metabolic changes and allows identification of a large number of new compounds in arabidopsis

Metabolomics is facing a major challenge: the lack of knowledge about metabolites present in a given biological system. Thus, large- scale discovery of metabolites is considered an essential step toward a better understanding of plant metabolism. We show here that the application of a metabolomics approach generating structural information for the analysis of Arabidopsis (Arabidopsis thaliana) mutants allows the efficient cataloging ofmetabolites. Fifty- six percent of the features that showed significant differences in abundance between seeds of wild- type, transparent testa4, and transparent testa5 plants could be annotated. Seventyfive compounds were structurally characterized, 21 of which could be identified. About 40 compounds had not been known from Arabidopsis before. Also, the high- resolution analysis revealed an unanticipated expansion of metabolic conversions upstream of biosynthetic blocks. Deficiency in chalcone synthase results in the increased seed- specific biosynthesis of a range of phenolic choline esters. Similarly, a lack of chalcone isomerase activity leads to the accumulation of various naringenin chalcone derivatives. Furthermore, our data provide insight into the connection between p- coumaroyl- coenzyme A- dependent pathways. Lack of flavonoid biosynthesis results in elevated synthesis not only of p- coumarate- derived choline esters but also of sinapatederived metabolites. However, sinapoylcholine is not the only accumulating end product. Instead, we observed specific and sophisticated changes in the complex pattern of sinapate derivatives.