Zhang Yao, Yu Jingyi, Wang Xuan, Durachko Daniel M, Zhang Sulin, Cosgrove Daniel J
Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.
Department of Engineering Science and Mechanics and Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA.
Science. 2021 May 14;372(6543):706-711. doi: 10.1126/science.abf2824.
Plants have evolved complex nanofibril-based cell walls to meet diverse biological and physical constraints. How strength and extensibility emerge from the nanoscale-to-mesoscale organization of growing cell walls has long been unresolved. We sought to clarify the mechanical roles of cellulose and matrix polysaccharides by developing a coarse-grained model based on polymer physics that recapitulates aspects of assembly and tensile mechanics of epidermal cell walls. Simple noncovalent binding interactions in the model generate bundled cellulose networks resembling that of primary cell walls and possessing stress-dependent elasticity, stiffening, and plasticity beyond a yield threshold. Plasticity originates from fibril-fibril sliding in aligned cellulose networks. This physical model provides quantitative insight into fundamental questions of plant mechanobiology and reveals design principles of biomaterials that combine stiffness with yielding and extensibility.
植物已经进化出基于纳米纤维的复杂细胞壁，以应对各种生物学和物理限制。生长中的细胞壁从纳米尺度到中尺度的组织如何产生强度和可扩展性，长期以来一直没有得到解决。我们试图通过开发一个基于聚合物物理学的粗粒度模型来阐明纤维素和基质多糖的力学作用，该模型概括了表皮细胞壁的组装和拉伸力学方面。模型中简单的非共价结合相互作用产生了类似于初生细胞壁的束状纤维素网络，并具有应力依赖性弹性、硬化以及超过屈服阈值后的可塑性。可塑性源于排列整齐的纤维素网络中纤维与纤维之间的滑动。这个物理模型为植物机械生物学的基本问题提供了定量的见解，并揭示了将刚度与屈服性和可扩展性相结合的生物材料的设计原则。
