Plant secondary metabolism is an active research area because of the unique and important roles the specialized metabolites have in the interaction of plants with their biotic and abiotic environment, the diversity and complexity of the compounds and their importance to human medicine. Thousands of natural accessions of Arabidopsis thaliana characterized with increasing genomic precision are available, providing new opportunities to explore the biochemical and genetic mechanisms affecting variation in secondary metabolism within this model species. In this study, we focused on four aromatic metabolites that were differentially accumulated among 96 Arabidopsis natural accessions as revealed by leaf metabolic profiling. Using UV, mass spectrometry, and NMR data, we identified these four compounds as different dihydroxybenzoic acid (DHBA) glycosides, namely 2,5-dihydroxybenzoic acid (gentisic acid) 5-O-β-D-glucoside, 2,3-dihydroxybenzoic acid 3-O-β-D-glucoside, 2,5-dihydroxybenzoic acid 5-O-β-D-xyloside, and 2,3-dihydroxybenzoic acid 3-O-β-D-xyloside. Quantitative trait locus (QTL) mapping using recombinant inbred lines generated from C24 and Col-0 revealed a major-effect QTL controlling the relative proportion of xylosides vs. glucosides. Association mapping identified markers linked to a gene encoding a UDP glycosyltransferase gene. Analysis of Transfer DNA (T-DNA) knockout lines verified that this gene is required for DHBA xylosylation in planta and recombinant protein was able to xylosylate DHBA in vitro. This study demonstrates that exploiting natural variation of secondary metabolism is a powerful approach for gene function discovery.
glycosides, Arabidopsis, Secondary metabolism, Natural variation, dihydrozybenzoic acid, UDP glycosyltransferase (UGT)
Publication DOI: 10.1534/genetics.114.168690Journal NLM ID: 0374636Publisher: Baltimore, MD: Genetics Society of America
Correspondence: chapple@purdue.edu, bdilkes@purdue.edu
Institutions: Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907, Purdue Interdepartmental NMR Facility, Purdue University, West Lafayette, Indiana 47907, Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, Department of Plant Sciences, University of California, Davis, California 95616
Methods: 13C NMR, 1H NMR, HPLC, LC-MS, enzymatic assay, genetic manipulations
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