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Abstract Detail


Metabolism

Yonekura-Sakakibara, Keiko [1], Tohge, Takayuki [2], Niida, Rie [2], Saito, Kazuki [3].

Functional Identification of a flavonol 7-O-rhamnosyltransferase gene from Arabidopsis: Comprehensive approach by transcriptome coexpression analysis, targeted metabolite analysis and reverse genetics.

Glycosylation plays a major role in the remarkable chemical diversity of secondary metabolites including flavonoids, phenylpropanoids and terpenoids in plants. The huge diversity of the large Family 1 glycosyltransferase (UGT) gene 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 and flavonoid target analysis to identify a gene that is prominent in determining the flavonoid composition of Arabidopsis. Using transcriptome coexpression analysis accessible on the ATTED-II public database, the expression pattern of a UGT gene, UGT1, was found to be highly correlated with known flavonoid biosynthetic genes. No C-7 rhamnosylated flavonols were detected in two independent ugt1 knockout mutants. This specific deficiency was complemented by stable transformation with the genomic fragment containing intact UGT1. GST-fused recombinant UGT1 protein converted kaempferol 3-O-glucoside to kaempferol 3-O-glucoside-7-O-rhamnoside. These results show that UGT1 functions as flavonol 7-O-rhamnosyltransferase. The abundance of UGT1 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 of a metabolic pathway multigene family in Arabidopsis.


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1 - RIKEN Plant Science Center, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama, 2300045, Japan
2 - RIKEN Plant Science Center
3 - RIKEN Plant Science Center, Chiba University, Graduate School of Pharmaceutical Science

Keywords:
glycosyltransferase
flavonoid
coexpression analysis
transcriptome
Arabidopsis thaliana.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P19009
Abstract ID:275


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