Studies on the physical process of development and maturation of tree cells

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The objective of this research is to investigate the role of the diurnal change of turgor pressure in the newly formed cells on the cell wall formation. That is, the shrinkage/expansion of the cell wall due to the turgor pressure change cases an influence to the deposition of the lignin and cellulose.In this fiscal year, the final year of this research, we succeeded in visualizing the diurnal difference in the deposition of cell wall substance.The differentiating cells were collected from Sugi, Cryptomeria japonica D.Don planted in the nursery in the campus of Nagoya University, at AM 6 : 00 when the tangential strain on the inner bark showed the maximum expansion. In the similar way, the cambium cells were collected at PM 4 : 00 when the tangential strain reached its minimum strain. Both sample were subjected to the SEM-EDX analysis after selective staining of glucomannan by means of an immunogold labelling method.The result showed that the microfibrils were clearly observed on the inner surface of differentiating tracheid of the specimens collected at daytime. That is no gold particles were observed. While, on the inner surface of tracheid in the specimen prepared at am 6 : 00, many gold particles adhered to the amorphous substance were clearly observed. Microfibrils formed in the daytime were not visible due to the amorphous materials.As the conclusion, diurnal periodicity was confirmed in the deposition of cell wall substance. That is, cellulose is deposited on the cell walls in the daytime, while hemi-celluloses are deposited in the nighttime.