College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
New Phytol. 2015 May;206(3):1051-1062. doi: 10.1111/nph.13282. Epub 2015 Jan 23.
Silicon (Si) plays a large number of diverse roles in plants, but the structural and chemical mechanisms operating at the single-cell level remain unclear. We isolate the cell walls from suspension-cultured individual cells of rice (Oryza sativa) and fractionate them into three main fractions including cellulose (C), hemicellulose (HC) and pectin (P). We find that most of the Si is in HC as determined by inductively coupled plasma-mass spectrometry (ICP-MS), where Si may covalently crosslink the HC polysacchrides confirmed by X-ray photoelectron spectroscopy (XPS). The HC-bound form of Si could improve both the mechanical property and regeneration of the cell walls investigated by a combination of atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). This study provides further evidence that HC could be the major ligand bound to Si, which broadens our understanding of the chemical nature of 'anomalous' Si in plant cell walls.
硅（Si）在植物中扮演着许多不同的角色，但在单细胞水平上起作用的结构和化学机制仍不清楚。我们从悬浮培养的水稻（Oryza sativa）单个细胞中分离细胞壁，并将其分为包括纤维素（C）、半纤维素（HC）和果胶（P）在内的三个主要部分。我们通过电感耦合等离子体质谱法（ICP-MS）发现，大部分 Si 存在于 HC 中，这表明 Si 可能通过共价键交联 HC 多糖，这一点通过 X 射线光电子能谱法（XPS）得到了证实。通过原子力显微镜（AFM）和共聚焦激光扫描显微镜（CLSM）的组合研究，HC 结合形式的 Si 可以改善细胞壁的机械性能和再生能力。这项研究进一步证明了 HC 可能是与 Si 结合的主要配体，这拓宽了我们对植物细胞壁中“异常”Si 的化学性质的理解。
