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

本研究的目的是探讨新形成的细胞中胀压的日变化在细胞壁形成中的作用。也就是说，由于胀压变化引起的细胞壁的收缩/膨胀对木质素和纤维素的沉积有影响。在本财政年度，也就是本研究的最后一年，我们成功地可视化了细胞壁物质沉积的日差异。在名古屋大学校园苗圃种植的杉木（Sugi, Cryptomeria japonica d.d . don）中，于上午6点内皮切向菌株膨胀最大时采集分化细胞。同样，当切向应变达到最小应变时，在下午4:00采集形成层细胞。通过免疫金标记法对葡甘露聚糖进行选择性染色后，对两种样品进行SEM-EDX分析。结果表明，白天采集的标本在分化管胞内表面可见明显的微原纤维。也就是说没有观察到金颗粒。而在上午6点制备的管胞内表面，可以清楚地观察到许多金颗粒粘附在无定形物质上。由于无定形物质，白天形成的微原纤维不可见。结果表明，细胞壁物质的沉积具有日周期性。也就是说，纤维素在白天沉积在细胞壁上，而半纤维素在夜间沉积。

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.