Abnormal glycosphingolipid mannosylation triggers salicylic acid-mediated responses in Arabidopsis

Plant Cell. 2013 May;25(5):1881-94. doi: 10.1105/tpc.113.111500. Epub 2013 May 21.


The Arabidopsis thaliana protein GOLGI-LOCALIZED NUCLEOTIDE SUGAR TRANSPORTER (GONST1) has been previously identified as a GDP-d-mannose transporter. It has been hypothesized that GONST1 provides precursors for the synthesis of cell wall polysaccharides, such as glucomannan. Here, we show that in vitro GONST1 can transport all four plant GDP-sugars. However, gonst1 mutants have no reduction in glucomannan quantity and show no detectable alterations in other cell wall polysaccharides. By contrast, we show that a class of glycosylated sphingolipids (glycosylinositol phosphoceramides [GIPCs]) contains Man and that this mannosylation is affected in gonst1. GONST1 therefore is a Golgi GDP-sugar transporter that specifically supplies GDP-Man to the Golgi lumen for GIPC synthesis. gonst1 plants have a dwarfed phenotype and a constitutive hypersensitive response with elevated salicylic acid levels. This suggests an unexpected role for GIPC sugar decorations in sphingolipid function and plant defense signaling. Additionally, we discuss these data in the context of substrate channeling within the Golgi.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Biological Transport / genetics
  • Cell Wall / genetics
  • Cell Wall / metabolism
  • Glycosphingolipids / metabolism*
  • Glycosylation
  • Golgi Apparatus / metabolism
  • Guanosine Diphosphate Fucose / metabolism
  • Guanosine Diphosphate Mannose / metabolism
  • Guanosine Diphosphate Sugars / metabolism
  • Immunoblotting
  • Mannose / metabolism*
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism*
  • Microscopy, Fluorescence
  • Mutation
  • Salicylic Acid / metabolism*


  • Arabidopsis Proteins
  • GONST1 protein, Arabidopsis
  • Glycosphingolipids
  • Guanosine Diphosphate Sugars
  • Membrane Transport Proteins
  • Guanosine Diphosphate Fucose
  • Guanosine Diphosphate Mannose
  • guanosine diphosphate glucose
  • Salicylic Acid
  • Mannose