Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
J R Soc Interface. 2023 Jul;20(204):20230001. doi: 10.1098/rsif.2023.0001. Epub 2023 Jul 5.
We use the model system as a vehicle to study the origin and propagation of surface nano-ridges in plant petal epidermal cells by tracking the development of the cell shape and the cuticle. In this system, the cuticle develops two distinct sub-layers, (i) an uppermost layer which increases in thickness and in-plane extension and (ii) a substrate, composed of cuticular and cell wall material. We quantify the pattern formation and geometrical changes and then postulate a mechanical model assuming that the cuticle behaves as a growing bi-layer. The model is a quasi-static morphoelastic system and it is numerically investigated in two- and three-dimensional settings, using different laws of film and substrate expansion and boundary conditions. We recreate several features of the observed developmental trajectories in petals. We establish the respective roles of the layers' stiffness mismatch, the underlying cell-wall curvature, the cell in-plane expansion and the thickness growth rates of the layers in determining the observed pattern features, such as the variance observed in the amplitude and wavelength of the cuticular striations. Our observations provide evidence which justifies the growing bi-layer description, and provide valuable insights into why some systems develop surface patterns and others do not.
我们使用该模型系统作为工具，通过追踪细胞形状和角质层的发育，研究植物花瓣表皮细胞中表面纳米脊的起源和传播。在这个系统中，角质层形成两个明显的亚层：（i）最上层，厚度和平面延伸增加；（ii）一个由角质层和细胞壁物质组成的底层。我们对图案形成和几何变化进行量化，然后假设一个假设角质层作为一个生长的双层的力学模型。该模型是一个准静态的形态弹性系统，在二维和三维环境中进行数值研究，使用不同的薄膜和底层扩展规律以及边界条件。我们再现了花瓣中观察到的几个发育轨迹特征。我们确定了层间的硬度失配、底层细胞壁曲率、细胞平面扩张以及层厚度增长率在确定观察到的图案特征中的各自作用，例如观察到的角质条纹幅度和波长的变化。我们的观察结果为生长双层描述提供了证据，并为为什么有些系统会形成表面图案而有些系统不会形成表面图案提供了有价值的见解。
