SE187:/DS1

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Sample Set Information

ID TSE1346
Title Identification of a flavonol 7-O-rhamnosyltransferase gene determining flavonoid pattern in Arabidopsis by transcriptome coexpression analysis and reverse genetics.
Description Glycosylation plays a major role in the remarkable chemical diversity of flavonoids in plants including Arabidopsis thaliana. The wide diversity encoded by the large family-1 glycosyltransferase (UGT) gene family makes it difficult to determine the biochemical function of each gene solely from its primary sequence. Here we used transcriptome coexpression analysis combined with a reverse genetics approach to identify a gene that is prominent in determining the flavonoid composition of Arabidopsis. Using transcriptome coexpression analysis accessible on the ATTED-II public data base, the expression pattern of a UGT gene, UGT89C1, was found to be highly correlated with known flavonoid biosynthetic genes. No C-7 rhamnosylated flavonols were detected in either of two T-DNA ugt89c1 mutants. This specific metabolite deficiency in the mutants was complemented by stable transformation with the genomic fragment containing intact UGT89C1. Glutathione S-transferasefused recombinant UGT89C1 protein converted kaempferol 3-O-glucoside to kaempferol 3-O-glucoside-7-O-rhamnoside and recognized 3-O-glycosylated flavonols and UDP-rhamnose as substrates, but not flavonol aglycones, 3-O-glycosylated anthocyanins or other UDP-sugars. These results show that UGT89C1 is a flavonol 7-O-rhamnosyltransferase. The abundance of UGT89C1 transcripts in floral buds was consistent with the flavonoid accumulation of C-7 rhamnosylated flavonols in Arabidopsis organs. Our present study demonstrates that the integration of transcriptome coexpression analysis with a reverse genetic approach is a versatile tool for understanding a multigene family of a metabolic pathway in Arabidopsis.
Authors Yonekura-Sakakibara, K., Tohge, T., Niida, R. and Saito, K.
Reference J Biol Chem. 2007 May 18;282(20):14932-41
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Data Analysis Details Information

ID DS1
Title Data analysis
Description Identification of the peaks in the plant extracts was based on comparisons of retention times, UV-visible absorption spectra, and mass fragmentation patterns by tandem MS analysis of the flavonoid standards. Other flavonoids with no standard compounds were annotated by comparison with the reported data in the UV-visible absorption spectra, elution time, m/z values, and MS2 fragmentation patterns.
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