Department of Biophysics and Morphogenesis of Plants, University of Silesia in Katowice, Katowice, Poland.
J Exp Bot. 2018 Aug 14;69(18):4349-4362. doi: 10.1093/jxb/ery237.
The relatively thick primary walls of epidermal and collenchyma cells often form waviness on the surface that faces the protoplast when they are released from the tensile in-plane stress that operates in situ. This waviness is a manifestation of buckling that results from the heterogeneity of the elastic strain across the wall. In this study, this heterogeneity was confirmed by the spontaneous bending of isolated wall fragments that were initially flat. We combined the empirical data on the formation of waviness in growing cell walls with computations of the buckled wall shapes. We chose cylindrical-shaped organs with a high degree of longitudinal tissue stress because in such organs the surface deformation that accompanies the removal of the stress is strongly anisotropic and leads to the formation of waviness in which wrinkles on the inner wall surface are always transverse to the organ axis. The computations showed that the strain heterogeneity results from individual or overlaid gradients of pre-stress and stiffness across the wall. The computed wall shapes depend on the assumed wall thickness and mechanical gradients. Thus, a quantitative analysis of the wall waviness that forms after stress removal can be used to assess the mechanical heterogeneity of the cell wall.
当表皮细胞和厚角组织细胞的初生壁从原位作用的面内拉伸应力中释放出来时，它们相对较厚的初生壁常常在面向原生质体的表面形成波纹。这种波纹是由于细胞壁的弹性应变的非均一性导致的屈曲的表现。在这项研究中，通过最初是平坦的分离壁片段的自发弯曲证实了这种非均一性。我们将生长细胞壁中波纹形成的经验数据与屈曲壁形状的计算相结合。我们选择了具有高度纵向组织应力的圆柱形器官，因为在这种器官中，伴随应力消除的表面变形具有强烈的各向异性，导致波纹的形成，其中内壁表面的皱纹始终垂直于器官轴。计算表明，应变的非均一性是由细胞壁上的预应力度和刚度的单独或叠加梯度引起的。计算出的壁形状取决于所假设的壁厚度和机械梯度。因此，对去除应力后形成的壁波纹的定量分析可用于评估细胞壁的力学异质性。
