Rhamnogalacturonan I in Solanum tuberosum tubers contains complex arabinogalactan structures

Phytochemistry. 2004 May;65(10):1429-38. doi: 10.1016/j.phytochem.2004.05.002.


A rhamnogalacturonan I polysaccharide was isolated from potato (Solanum tuberosum cv. Posmo) tuber cell walls and characterised by enzymatic digestion with an endo-beta-1 --> 4-galactanase and an endo-alpha-1 --> 5-arabinanase, individually or in combination. The reaction products were separated using size-exclusion chromatography and further analysed for monosaccharide composition and presence of epitopes using the LM5 anti-beta-1 --> 4-galactan and LM6 anti-alpha-1 --> 5-arabinan monoclonal antibodies. The analyses point to distinct structural features of potato tuber rhamnogalacturonan I, such as the abundance of beta-1 --> 4-galactan side chains that are poorly substituted with short arabinose-containing side chains, the presence of alpha-1 --> 5-arabinan side chains substituted with beta-1 --> 4-galactan oligomers (degree of polymerisation > 4), and the presence of alpha-1 --> 5-arabinans that resist enzymatic degradation. A synergy between the enzymes was observed towards the degradation of arabinans but not towards the degradation of galactans. The effect of the enzymes on isolated RG I is discussed in relation to documented effects of enzymes heterologously expressed in potato tubers. In addition, a novel and rapid method for the determination of the monosaccharide and uronic acid composition of cell wall polysaccharides using high-performance anion exchange chromatography with pulsed amperometric detection is described.

MeSH terms

  • Cell Wall / chemistry*
  • Galactans / analysis*
  • Pectins / chemistry*
  • Pectins / isolation & purification
  • Plant Roots / chemistry*
  • Solanum tuberosum / chemistry*


  • Galactans
  • rhamnogalacturonan I
  • Pectins
  • arabinogalactan