title: The accumulation pattern of ferruginol in the heartwood-forming Cryptomeria japonica xylem as determined by time-of-flight secondary ion mass spectrometry and quantity analysis.
abstract: OBJECTIVE
  Heartwood formation is a unique phenomenon of tree species. Although the accumulation of heartwood substances is a well-known feature of the process, the accumulation mechanism remains unclear. The aim of this study was to determine the accumulation process of ferruginol, a predominant heartwood substance of Cryptomeria japonica, in heartwood-forming xylem.
  
  
  METHODS
  The radial accumulation pattern of ferruginol was examined from sapwood and through the intermediate wood to the heartwood by direct mapping using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The data were compared with quantitative results obtained from a novel method of gas chromatography analysis using laser microdissection sampling and with water distribution obtained from cryo-scanning electron microscopy.
  
  
  RESULTS
  Ferruginol initially accumulated in the middle of the intermediate wood, in the earlywood near the annual ring boundary. It accumulated throughout the entire earlywood in the inner intermediate wood, and in both the earlywood and the latewood in the heartwood. The process of ferruginol accumulation continued for more than eight annual rings. Ferruginol concentration peaked at the border between the intermediate wood and heartwood, while the concentration was less in the latewood compared with the earlywood in each annual ring. Ferruginol tended to accumulate around the ray parenchyma cells. In addition, at the border between the intermediate wood and heartwood, the accumulation was higher in areas without water than in areas with water.
  
  
  CONCLUSIONS
  TOF-SIMS clearly revealed ferruginol distribution at the cellular level. Ferruginol accumulation begins in the middle of intermediate wood, initially in the earlywood near the annual ring boundary, then throughout the entire earlywood, and finally across to the whole annual ring in the heartwood. The heterogeneous timing of ferruginol accumulation could be related to the distribution of ray parenchyma cells and/or water in the heartwood-forming xylem.
authors.affiliation: Department of Wood Properties, Forestry and Forest Products Research Institute, Tsukuba 305-8687, Japan.
authors.forename: Katsushi
authors.initials: K
authors.lastname: Kuroda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Koh
authors.initials: K
authors.lastname: Hashida
authors.forename: Takanori
authors.initials: T
authors.lastname: Imai
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Kushi
authors.forename: Kaori
authors.initials: K
authors.lastname: Saito
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Fukushima
mesh_terms: D045784:Abietanes / Q000378:metabolism*; D032485:Cryptomeria / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D018629:Spectrometry, Mass, Secondary Ion / Q000379:methods*; D052584:Xylem / Q000378:metabolism*
chemical_list: D045784:Abietanes; C431074:ferruginol
keywords: Cryptomeria japonica; GC; LMD; TOF-SIMS; Wood formation; cryo-SEM; cryo-scanning electron microscopy; earlywood; extractives; ferruginol; gas chromatography; heartwood substances; intermediate wood; laser microdissection; parenchyma cell; time-of-flight secondary ion mass spectrometry; water