Over-expression of UDP-glucose pyrophosphorylase in hybrid poplar affects carbon allocation

Heather D. Coleman, Thomas Canam, Kyu Young Kang, David D. Ellis, Shawn D. Mansfield

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


The effects of the over-expression of the Acetobacter xylinum UDP-glucose pyrophosphorylase (UGPase) under the control of the tandem repeat Cauliflower Mosaic Virus promoter (2x35S) on plant metabolism and growth were investigated in hybrid poplar (Populus albaxgrandidentata). Transcript levels, enzyme activity, growth parameters, leaf morphology, structural and soluble carbohydrates, and soluble metabolite levels were quantified in both transgenic and wild-type trees. Transgenic 2x35S::UGPase poplar showed impaired growth rates, displaying reduced height growth and stem diameter. Morphologically, 2x35S::UGPase trees had elongated axial shoots, and leaves that were substantially smaller in size when compared with wild-type trees at equivalent developmental stages. Biochemical analysis revealed significant increases in soluble sugar, starch, and cellulose contents, and concurrent decreases in lignin content. Lignin monomer composition was altered in favour of syringyl moieties. Detailed soluble metabolite analysis revealed that 2x35S::UGPase trees had as much as a 270-fold increase in the salicylic acid 2-O-β-D-glucoside (SAG), a compound typically associated with the stress response. These data suggest that while it is possible to alter the allocation of carbon in favour of cellulose biosynthesis, whole plant changes result in unexpected decreases in growth and an increase in defence metabolites.

Original languageEnglish (US)
Pages (from-to)4257-4268
Number of pages12
JournalJournal of Experimental Botany
Issue number15-16
StatePublished - Dec 2007
Externally publishedYes


  • Carbon allocation
  • Cellulose
  • Hybrid poplar
  • Sucrose metabolism
  • UDP-glucose
  • UDP-glucose pyrophosphorylase

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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