title: Improved resistance to oxidative stress by a loss-of-function mutation in the Arabidopsis UGT71C1 gene.
abstract: Approximately 120 UDP-glycosyltransferases (UGTs), which are classified into 14 distinct groups (A to N), have been annotated in the Arabidopsis genome. UGTs catalyze the transfer of sugars to various acceptor molecules including flavonoids. Previously, UGT71C1 was shown to glycosylate the 3-OH of hydroxycinnamates and flavonoids in vitro. Such secondary metabolites are known to play important roles in plant growth and development. To help define the role of UGT71C1 in planta, we investigated its expression patterns, and isolated and characterized a loss-of-function mutation in the UGT71C1 gene (named ugt71c1-1). Our analyses by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR), microarray data mining, and histochemical detection of GUS activity driven by the UGT71C1 promoter region, revealed the tissue-specific expression patterns of UGT71C1 with highest expression in roots. Interestingly, upon treatment with methyl viologen (MV, paraquat), ugt71c1-1 plants displayed enhanced resistance to oxidative stress, and ROS scavenging activity was higher than normal. Metabolite profiling revealed that the levels of two major glycosides of quercetin and kaempferol were reduced in ugt71c1-1 plants. In addition, when exposed to MV-induced oxidative stress, eight representative ROS response genes were expressed at lower levels in ugt71c1-1 plants, indicating that ugt71c1-1 probably has higher non-enzymatic antioxidant activity. Taken together, our results indicate that ugt71c1-1 has increased resistance to oxidative stress, suggesting that UGT71C1 plays a role in some glycosylation pathways affecting secondary metabolites such as flavonoids in response to oxidative stress.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul 143-701, Korea.
authors.forename: Chae Eun
authors.initials: CE
authors.lastname: Lim
authors.forename: Jung Nam
authors.initials: JN
authors.lastname: Choi
authors.forename: In A
authors.initials: IA
authors.lastname: Kim
authors.forename: Shin Ae
authors.initials: SA
authors.lastname: Lee
authors.forename: Yong-Sic
authors.initials: YS
authors.lastname: Hwang
authors.forename: Choong Hwan
authors.initials: CH
authors.lastname: Lee
authors.forename: Jun
authors.initials: J
authors.lastname: Lim
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D018384:Oxidative Stress; D010269:Paraquat / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D016695:Glycosyltransferases; C531120:UGT71C1 protein, Arabidopsis; D010269:Paraquat