Skip to main content
padlock icon - secure page this page is secure

Free Content Arabidopsis glucosyltransferase UGT74B1 functions in glucosinolate biosynthesis and auxin homeostasis

Download Article:
(PDF 661.3 kb)

Glucosinolates are a class of secondary metabolites with important roles in plant defense and human nutrition. Here, we characterize a putative UDP-glucose:thiohydroximate S-glucosyltransferase, UGT74B1, to determine its role in the Arabidopsis glucosinolate pathway. Biochemical analyses demonstrate that recombinant UGT74B1 specifically glucosylates the thiohydroximate functional group. Low Km values for phenylacetothiohydroximic acid (approximately 6 μm) and UDP-glucose (approximately 50 μm) strongly suggest that thiohydroximates are in vivo substrates of UGT74B1. Insertional loss-of-function ugt74b1 mutants exhibit significantly decreased, but not abolished, glucosinolate accumulation. In addition, ugt74b1 mutants display phenotypes reminiscent of auxin overproduction, such as epinastic cotyledons, elongated hypocotyls in light-grown plants, excess adventitious rooting and incomplete leaf vascularization. Indeed, during early plant development, mutant ugt74b1 seedlings accumulate nearly threefold more indole-3-acetic acid than the wild type. Other phenotypes, however, such as chlorosis along the leaf veins, are likely caused by thiohydroximate toxicity. Analysis of UGT74B1 promoter activity during plant development reveals expression patterns consistent with glucosinolate metabolism and induction by auxin treatment. The results are discussed in the context of known mutations in glucosinolate pathway genes and their effects on auxin homeostasis. Taken together, our work provides complementary in vitro and in vivo evidence for a primary role of UGT74B1 in glucosinolate biosynthesis.
No References
No Citations
No Supplementary Data
No Article Media
No Metrics

Keywords: auxin; glucosinolate pathway; glucosyltransferase; secondary metabolism; thioglycosides; thiohydroximates

Document Type: Research Article

Affiliations: 1: Department of Plant Sciences, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA, 2: Institut für Botanik, Technische Universität Dresden, Zellescher Weg 22, D-01062, Germany, and 3: Department of Chemistry, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA

Publication date: December 1, 2004

  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more