Pectin May Hinder the Unfolding of Xyloglucan Chains during Cell Deformation: Implications of the Mechanical Performance of Arabidopsis Hypocotyls with Pectin Alterations
Pectin May Hinder the Unfolding of Xyloglucan Chains during Cell Deformation: Implications of the Mechanical Performance of Arabidopsis Hypocotyls with Pectin Alterations
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DOI：
10.1093/mp/ssp065
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发表时间：
2009-09-01
期刊：
影响因子：
27.5
通讯作者：
Burgert, Ingo
中科院分区：
文献类型：
--
作者：
Abasolo, Willie;Eder, Michaela;Burgert, Ingo
植物细胞壁，像许多其他生物材料一样，是天然纤维增强复合材料。它们的机械性能高度依赖于刚性纤维相和软基质相的相互作用以及基质变形本身。使用特定的拟南芥突变体，我们研究了机械作用的下胚轴与改变木葡聚糖和果胶组合物的初级细胞壁的矩阵组件。对mur 1下胚轴进行标准微拉伸试验和循环加载方案，其具有受影响的RGII硼酸二酯交联和受阻的木葡聚糖岩藻糖基化，以及与野生型相比表现出50%更少的同型半乳糖醛酸的qua 2。作为对照，利用野生型植物（Col-0）和mur 2，其表现出特定的木葡聚糖岩藻糖基化并且在果胶网络中没有差异。在标准拉伸试验中，果胶改变的突变体（mur 1，qua 2）的下胚轴的极限应力水平（类似于拉伸强度）相当不受影响，而它们的拉伸刚度与Col-0相比显著降低。循环载荷试验表明，所有下胚轴的硬化后的第一个周期和塑性变形期间的第一个应变，其中的程度，但是，mur 1和qua 2下胚轴要高得多。基于机械数据和当前的细胞壁模型，假设纤维素原纤维之间的折叠的木葡聚糖链可能在下胚轴的应变期间倾向于展开。这种反应可能是由于果胶刚性的几何约束阻碍。
Plant cell walls, like a multitude of other biological materials, are natural fiber-reinforced composite materials. Their mechanical properties are highly dependent on the interplay of the stiff fibrous phase and the soft matrix phase and on the matrix deformation itself. Using specific Arabidopsis thaliana mutants, we studied the mechanical role of the matrix assembly in primary cell walls of hypocotyls with altered xyloglucan and pectin composition. Standard microtensile tests and cyclic loading protocols were performed on mur1 hypocotyls with affected RGII borate diester cross-links and a hindered xyloglucan fucosylation as well as qua2 exhibiting 50% less homogalacturonan in comparison to wild-type. As a control, wild-type plants (Col-0) and mur2 exhibiting a specific xyloglucan fucosylation and no differences in the pectin network were utilized. In the standard tensile tests, the ultimate stress levels (similar to tensile strength) of the hypocotyls of the mutants with pectin alterations (mur1, qua2) were rather unaffected, whereas their tensile stiffness was noticeably reduced in comparison to Col-0. The cyclic loading tests indicated a stiffening of all hypocotyls after the first cycle and a plastic deformation during the first straining, the degree of which, however, was much higher for mur1 and qua2 hypocotyls. Based on the mechanical data and current cell wall models, it is assumed that folded xyloglucan chains between cellulose fibrils may tend to unfold during straining of the hypocotyls. This response is probably hindered by geometrical constraints due to pectin rigidity.