Spatial organization of cellulose microfibrils and matrix polysaccharides in primary plant cell walls as imaged by multichannel atomic force microscopy
Spatial organization of cellulose microfibrils and matrix polysaccharides in primary plant cell walls as imaged by multichannel atomic force microscopy
复制标题
DOI：
10.1111/tpj.13102
复制
发表时间：
2016-01-01
期刊：
影响因子：
7.2
通讯作者：
Cosgrove, Daniel J.
中科院分区：
文献类型：
--
作者：
Zhang, Tian;Zheng, Yunzhen;Cosgrove, Daniel J.
我们使用原子力显微镜（AFM），辅以电子显微镜，表征的纳米级和中尺度结构的外部（平周）细胞壁的洋葱鳞片表皮-模型系统有关壁结构的细胞壁力学。表皮壁包含类似于100个薄片，每个薄片类似于40 nm厚，包含3.5 nm宽的纤维素微纤维，其在薄片内以共同方向取向，但在相邻薄片之间变化类似于30至90度。因此，壁具有交叉的多片层，而不是螺旋状的壁结构。新沉积的壁表面的高分辨率AFM图像的蒙太奇显示，单个微纤丝合并成和出微纤丝束的短区域，从而形成网状网络。微纤维方向内的薄层没有逐渐或突然改变整个面对的细胞，表明连续性的薄层整个外壁。当通过FESEM成像时，壁表面处的果胶层遮蔽了下面的纤维素微纤维，但不是通过AFM。因此，AFM通过探测这些水合壁中的软基质来优先检测纤维素微纤丝。AFM为基础的纳米力学地图显示，在纳米尺度的细胞壁刚度和硬度显着的异质性。通过颜色编码和合并这些地图，软和刚性基质聚合物的空间分布可以在更硬的微纤维的情况下可视化。没有化学提取和脱水，我们的研究结果提供了多尺度的结构细节的初生细胞壁在其近原生状态，在单轴和双轴拉伸过程中的微纤丝运动在不同的lamelles的影响。
We used atomic force microscopy (AFM), complemented with electron microscopy, to characterize the nanoscale and mesoscale structure of the outer (periclinal) cell wall of onion scale epidermis - a model system for relating wall structure to cell wall mechanics. The epidermal wall contains similar to 100 lamellae, each similar to 40 nm thick, containing 3.5-nm wide cellulose microfibrils oriented in a common direction within a lamella but varying by similar to 30 to 90 degrees between adjacent lamellae. The wall thus has a crossed polylamellate, not helicoidal, wall structure. Montages of high-resolution AFM images of the newly deposited wall surface showed that single microfibrils merge into and out of short regions of microfibril bundles, thereby forming a reticulated network. Microfibril direction within a lamella did not change gradually or abruptly across the whole face of the cell, indicating continuity of the lamella across the outer wall. A layer of pectin at the wall surface obscured the underlying cellulose microfibrils when imaged by FESEM, but not by AFM. The AFM thus preferentially detects cellulose microfibrils by probing through the soft matrix in these hydrated walls. AFM-based nanomechanical maps revealed significant heterogeneity in cell wall stiffness and adhesiveness at the nm scale. By color coding and merging these maps, the spatial distribution of soft and rigid matrix polymers could be visualized in the context of the stiffer microfibrils. Without chemical extraction and dehydration, our results provide multiscale structural details of the primary cell wall in its near-native state, with implications for microfibrils motions in different lamellae during uniaxial and biaxial extensions.