Identification of glucosyltransferase genes involved in sinapate metabolism and lignin synthesis in Arabidopsis

Sinapic acid is a major phenylpropanoid in Brassicaceae providing intermedi ates in two distinct metabolic pathways leading to sinapoyl esters and lign in synthesis. Glucosyltransferases play key roles in the formation of these intermediates, either through the production of the high energy compound 1 -O-sinapoyl-glucose leading to sinapoylmalate and sinapoylcholine or throug h the production of sinapyl alcohol-4-O-glucoside, potentially leading to t he syringyl units found in lignins. While the importance of these glucosylt ransferases has been recognized for more than 20 years, their corresponding genes have not been identified. Combining sequence information in the Arab idopsis genomic data base with biochemical data from screening the activity of recombinant proteins in vitro, we have now identified five gene sequenc es encoding enzymes that can glucosylate sinapic acid, sinapyl alcohol, and their related phenylpropanoids. The data provide a foundation for future u nderstanding and manipulation of sinapate metabolism and lignin biology in Arabidopsis.