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Official Journal of the Japan Wood Research Society

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Proteomic analysis of the G-layer in poplar tension wood


Angiosperm trees bend their stems by forming tension wood at the upper side of leaning stems. Most tension wood has a cellulose-rich G-layer in the innermost surface of the fiber cell wall. Strong tensile stress is considered to occur in the G-layer. This study undertook to identify the proteins involved in G-layer formation and function through a proteomic analysis of G-layer-localized protein. G-layers of poplar were loosened by sonication and isolated as doughnut-shaped pieces of thinly sliced transverse sections. The proteins, once extracted with urea/detergent solution, were separated by two-dimensional polyacrylamide gel electrophoresis, and 110 spots were subjected to liquid chromatography tandem mass spectrometry (LC/MS/MS). A database search for these spots’ mass spectrum patterns identified 72 proteins. In addition, all peptide digestion mixtures of G-layer proteins were separated by strong cation exchange chromatography and 39 proteins were identified using LC/MS/MS analysis. Proteins involved in wall formation, such as lignin biosynthesis-related protein, xyloglucan endotransglucosylase, and fasciclin-like arabinogalactan protein, were notably detected in the G-layer.


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Correspondence to Takahisa Hayashi.

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Kaku, T., Serada, S., Baba, K. et al. Proteomic analysis of the G-layer in poplar tension wood. J Wood Sci 55, 250–257 (2009).

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Key words

  • G-layer
  • Populus
  • Proteomics
  • Tension wood