The mechanical properties and molecular dynamics of plant cell wall polysaccharides studied by Fourier-transform infrared spectroscopy
The mechanical properties and molecular dynamics of plant cell wall polysaccharides studied by Fourier-transform infrared spectroscopy
复制标题
DOI：
10.1104/pp.124.1.397
复制
发表时间：
2000-09-01
期刊：
影响因子：
7.4
通讯作者：
Waldron, KW
中科院分区：
文献类型：
--
作者：
Wilson, RH;Smith, AC;Waldron, KW
在水分胁迫和机械胁迫条件下，获得了洋葱表皮的偏振一维和二维红外光谱。用傅里叶变换红外显微光谱法测定了单细胞壁中大分子的取向。纤维素和果胶在天然表皮细胞壁中表现出很小的取向，但是当机械应力施加在组织上时，这些分子随着细胞被拉长而表现出明显的重新取向。当应力被移除时，组织略微恢复，但相对较大的塑性变形仍然存在。通过保留组织内细胞的一些伸长和通过细胞壁的红外光谱中的残余分子取向，在显微图像中证实了塑性变形。二维红外光谱被用来确定变形过程中的多糖网络之间的相互作用的性质。结果提供的证据表明，纤维素和木葡聚糖协会，而果胶创建一个独立的网络，表现出不同的重定向率在湿洋葱细胞壁。果胶链对振荡的反应比更刚性的纤维素更快。
Polarized one- and two-dimensional infrared spectra were obtained from the epidermis of onion (Allium cepa) under hydrated and mechanically stressed conditions. By Fourier-transform infrared microspectroscopy, the orientation of macromolecules in single cell walls was determined. Cellulose and pectin exhibited little orientation in native epidermal cell walls, but when a mechanical stress was placed on the tissue these molecules showed distinct reorientation as the cells were elongated. When the stress was removed the tissue recovered slightly, but a relatively large plastic deformation remained. The plastic deformation was confirmed in microscopic images by retention of some elongation of cells within the tissue and by residual molecular orientation in the infrared spectra of the cell wall. Two-dimensional infrared spectroscopy was used to determine the nature of the interaction between the polysaccharide networks during deformation. The results provide evidence that cellulose and xyloglucan associate while pectin creates an independent network that exhibits different reorientation rates in the wet onion cell walls. The pectin chains respond faster to oscillation than the more rigid cellulose.