title: A rapid decrease in temperature induces latewood formation in artificially reactivated cambium of conifer stems.
abstract: OBJECTIVE
  Latewood formation in conifers occurs during the later part of the growing season, when the cell division activity of the cambium declines. Changes in temperature might be important for wood formation in trees. Therefore, the effects of a rapid decrease in temperature on cellular morphology of tracheids were investigated in localized heating-induced cambial reactivation in Cryptomeria japonica trees and in Abies firma seedlings.
  
  
  METHODS
  Electric heating tape and heating ribbon were wrapped on the stems of C. japonica trees and A. firma seedlings. Heating was discontinued when 11 or 12 and eight or nine radial files of differentiating and differentiated tracheids had been produced in C. japonica and A. firma stems, respectively. Tracheid diameter, cell wall thickness, percentage of cell wall area and percentage of lumen area were determined by image analysis of transverse sections and scanning electron microscopy.
  
  
  RESULTS
  Localized heating induced earlier cambial reactivation and xylem differentiation in stems of C. japonica and A. firma as compared with non-heated stems. One week after cessation of heating, there were no obvious changes in the dimensions of the differentiating tracheids in the samples from adult C. japonica. In contrast, tracheids with a smaller diameter were observed in A. firma seedlings after 1 week of cessation of heating. Two or three weeks after cessation of heating, tracheids with reduced diameters and thickened cell walls were found. The results showed that the rapid decrease in temperature produced slender tracheids with obvious thickening of cell walls that resembled latewood cells.
  
  
  CONCLUSIONS
  The results suggest that a localized decrease in temperature of stems induces changes in the diameter and cell wall thickness of differentiating tracheids, indicating that cambium and its derivatives can respond directly to changes in temperature.
authors: Tokyo University of Agriculture and Technology, Fuchu-Tokyo, Japan.
authors: Shahanara
authors: S
authors: Begum
authors: Satoshi
authors: S
authors: Nakaba
authors: Yusuke
authors: Y
authors: Yamagishi
authors: Kenichi
authors: K
authors: Yamane
authors: Md Azharul
authors: MA
authors: Islam
authors: Yuichiro
authors: Y
authors: Oribe
authors: Jae-Heung
authors: JH
authors: Ko
authors: Hyun-O
authors: HO
authors: Jin
authors: Ryo
authors: R
authors: Funada
mesh_terms: D028202:Abies / Q000166:cytology / Q000254:growth & development*; D058506:Cambium / Q000166:cytology / Q000254:growth & development*; D002455:Cell Division; D002473:Cell Wall / Q000378:metabolism; D032485:Cryptomeria / Q000166:cytology / Q000254:growth & development*; D006358:Hot Temperature; D018547:Plant Stems / Q000166:cytology / Q000254:growth & development; D012621:Seasons; D036226:Seedlings / Q000166:cytology / Q000254:growth & development; D013696:Temperature; D013997:Time Factors; D014197:Trees; D014934:Wood; D052584:Xylem / Q000166:cytology / Q000254:growth & development