Changes in the arrangement of cellulose microfibrils associated with the cessation of cell expansion in tracheids |
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Authors: | H Abe R Funada J Ohtani Kazumi Fukazawa |
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Institution: | (1) Department of Forest Science, Faculty of Agriculture, Hokkaido University, Sapporo 060, Japan, JP |
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Abstract: | The relationship between the cessation of cell expansion and formation of the secondary wall was investigated in the early-wood
tracheids of Abies sachalinensis Masters by image analysis and field emission scanning electron microscopy. The area of the lumen and the length of the perimeter
of the lumen of differentiating tracheids increased from the cambium towards the xylem. These increases had just ceased in
the case of tracheids closest to the cambium in which birefringence was first detected by observations with a polarizing light
microscope. Cellulose microfibrils (MFs) deposited on the innermost surfaces of radial walls were not well ordered during
the expansion of cells, but well ordered MFs were deposited at the subsequent stage of cell wall formation. The first well
ordered MFs were oriented in an S-helix. The well ordered MFs had already been deposited at the tracheids where birefringence was first detected under the
polarizing light microscope. These results indicate that the deposition of the well ordered MFs, namely, the formation of
the secondary wall, begins before the cessation of cell expansion of tracheids. Therefore, it seems that the expansion of
tracheids is restricted by the deposition of the secondary wall because the cell walls become rigid simultaneously with the
development of the secondary wall and, therefore, the yield point of cell walls exceeds the turgor pressure of the cell.
Received: 3 July 1996 / Accepted: 24 September 1996 |
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Keywords: | Cellulose microfibril Tracheid Cell expansion Abies sachalinensis Secondary wall formation |
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