Disentangling loosening from softening: insights into primary cell wall structure.
Disentangling loosening from softening: insights into primary cell wall structure.
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DOI：
10.1111/tpj.14519
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发表时间：
2019-09
期刊：
影响因子：
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通讯作者：
Tian Zhang;Haosu Tang;Dimitrios Vavylonis;D. Cosgrove
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文献类型：
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作者：
Tian Zhang;Haosu Tang;Dimitrios Vavylonis;D. Cosgrove
细胞壁弹性、可塑性和依赖时间的延伸(蠕变)如何相互关联，与植物细胞壁结构和细胞生长之间的关系仍然是悬而未决的话题。为了在不增加活组织复杂性的情况下研究这些问题，我们用不同的酶和其他试剂处理洋葱表皮壁的无细胞条带，以评估哪些多糖承担着细胞壁的平面内和平面外的机械力。这些信息对于整合壁结构、壁材料属性、组织力学和细胞生长机制的概念至关重要。利用原子力显微镜，我们还监测了治疗过程中壁面的实时变化。Driselase是一种有效的壁降解酶的混合物，它逐层顺序地去除浅层板层中的纤维素微纤维，并软化壁面(降低其机械硬度)，但不会导致壁面松动(蠕变)。相反，Cel12A，一种双功能的木聚糖酶/纤维素酶，诱导蠕变，只有微小的壁面变化。Driselase和Cel12A都提高了拉伸柔度，但对弹性和塑性成分的影响不同。用果胶裂解酶和钙螯合增溶高半乳糖醛酸，在不改变拉伸柔度的情况下，极大地提高了压痕柔度。酸性缓冲液通过内源α-Expansins诱导细胞壁快速蠕变，而对壁顺应性的影响可以忽略不计。我们的结论是，这些不同的墙体属性并不是紧密耦合的，因此反映了墙体结构的不同方面。纤维微原纤维的交叉层状网络影响蠕变和拉伸硬度，而同型半乳糖醛酸影响压痕力学。这些信息对于构建真实的分子模型至关重要，这些模型定义了壁力学和生长如何依赖于初级细胞壁结构。这篇文章受版权保护。版权所有。
How cell wall elasticity, plasticity, and time-dependent extension (creep) relate to one another, to plant cell wall structure and to cell growth remain unsettled topics. To examine these issues without the complexities of living tissues, we treated cell-free strips of onion epidermal walls with various enzymes and other agents to assess which polysaccharides bear mechanical forces in-plane and out-of-plane of the cell wall. This information is critical for integrating concepts of wall structure, wall material properties, tissue mechanics, and mechanisms of cell growth. With atomic force microscopy we also monitored real-time changes in the wall surface during treatments. Driselase, a potent cocktail of wall-degrading enzymes, removed cellulose microfibrils in superficial lamellae sequentially, layer-by-layer, and softened the wall (reduced its mechanical stiffness), yet did not induce wall loosening (creep). In contrast Cel12A, a bifunctional xyloglucanase/cellulase, induced creep with only subtle changes in wall appearance. Both Driselase and Cel12A increased the tensile compliance, but differently for elastic and plastic components. Homogalacturonan solubilization by pectate lyase and calcium chelation greatly increased the indentation compliance without changing tensile compliances. Acidic buffer induced rapid cell wall creep via endogenous α-expansins, with negligible effects on wall compliances. We conclude that these various wall properties are not tightly coupled and thus reflect distinctive aspects of wall structure. Cross-lamellate networks of cellulose microfibrils influenced creep and tensile stiffness whereas homogalacturonan influenced indentation mechanics. This information is crucial for constructing realistic molecular models that define how wall mechanics and growth depend on primary cell wall structure. This article is protected by copyright. All rights reserved.