Format

Send to

Choose Destination
J Biol Chem. 2007 May 18;282(20):14932-41. Epub 2007 Feb 21.

Identification of a flavonol 7-O-rhamnosyltransferase gene determining flavonoid pattern in Arabidopsis by transcriptome coexpression analysis and reverse genetics.

Author information

1
RIKEN Plant Science Center, Yokohama 230-0045, Japan.

Abstract

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.

PMID:
17314094
DOI:
10.1074/jbc.M611498200
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center