Suppression of CCR impacts metabolite profile and cell wall composition in Pinus radiata tracheary elements

Plant Mol Biol. 2013 Jan;81(1-2):105-17. doi: 10.1007/s11103-012-9985-z. Epub 2012 Nov 7.

Abstract

Suppression of the lignin-related gene cinnamoyl-CoA reductase (CCR) in the Pinus radiata tracheary element (TE) system impacted both the metabolite profile and the cell wall matrix in CCR-RNAi lines. UPLC-MS/MS-based metabolite profiling identified elevated levels of p-coumaroyl hexose, caffeic acid hexoside and ferulic acid hexoside in CCR-RNAi lines, indicating a redirection of metabolite flow within phenylpropanoid metabolism. Dilignols derived from coniferyl alcohol such as G(8-5)G, G(8-O-4)G and isodihydrodehydrodiconiferyl alcohol (IDDDC) were substantially depleted, providing evidence for CCR's involvement in coniferyl alcohol biosynthesis. Severe CCR suppression almost halved lignin content in TEs based on a depletion of both H-type and G-type lignin, providing evidence for CCR's involvement in the biosynthesis of both lignin types. 2D-NMR studies revealed minor changes in the H:G-ratio and consequently a largely unchanged interunit linkage distribution in the lignin polymer. However, unusual cell wall components including ferulate and unsaturated fatty acids were identified in TEs by thioacidolysis, pyrolysis-GC/MS and/or 2D-NMR in CCR-RNAi lines, providing new insights into the consequences of CCR suppression in pine. Interestingly, CCR suppression substantially promoted pyrolytic breakdown of cell wall polysaccharides, a phenotype most likely caused by the incorporation of acidic compounds into the cell wall matrix in CCR-RNAi lines.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aldehyde Oxidoreductases / antagonists & inhibitors*
  • Aldehyde Oxidoreductases / genetics*
  • Aldehyde Oxidoreductases / metabolism
  • Amino Acid Sequence
  • Base Sequence
  • Cell Wall / chemistry
  • Cell Wall / metabolism
  • DNA, Plant / genetics
  • Genes, Plant
  • Lignin / biosynthesis
  • Metabolome
  • Molecular Sequence Data
  • Monosaccharides / analysis
  • Nuclear Magnetic Resonance, Biomolecular
  • Pinus / genetics*
  • Pinus / metabolism*
  • Plant Proteins / antagonists & inhibitors*
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plants, Genetically Modified
  • RNA Interference
  • Sequence Homology, Amino Acid

Substances

  • DNA, Plant
  • Monosaccharides
  • Plant Proteins
  • Lignin
  • Aldehyde Oxidoreductases
  • cinnamoyl CoA reductase