Characterization of the ABA-regulated global responses to dehydration in Arabidopsis by metabolomics.

Drought is the major environmental threat to agricultural production and distribution worldwide. Adaptation by plants to dehydration stress is a complex biological process that involves global changes in gene expression and metabolite composition. Here, using one type of functional genomics analysis, metabolomics, we characterized the metabolic phenotypes of Arabidopsis wild-type and a knockout mutant of the NCED3 gene (nc3-2) under dehydration stress. NCED3 plays a role in the dehydration-inducible biosynthesis of abscisic acid (ABA), a phytohormone that is important in the dehydration-stress response in higher plants. Metabolite profiling performed using two types of mass spectrometry (MS) systems, gas chromatography/time-of-flight MS (GC/TOF-MS) and capillary electrophoresis MS (CE-MS), revealed that accumulation of amino acids depended on ABA production, but the level of the oligosaccharide raffinose was regulated by ABA independently under dehydration stress. Metabolic network analysis showed that global metabolite-metabolite correlations occurred in dehydration-increased amino acids in wild-type, and strong correlations with raffinose were reconstructed in nc3-2. An integrated metabolome and transcriptome analysis revealed ABA-dependent transcriptional regulation of the biosynthesis of the branched-chain amino acids, saccharopine, proline and polyamine. This metabolomics analysis revealed new molecular mechanisms of dynamic metabolic networks in response to dehydration stress.