Laboratoire de Reproduction et Développement des plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Inria, 69342, Lyon, France.
Bull Math Biol. 2019 Aug;81(8):3362-3384. doi: 10.1007/s11538-019-00622-z. Epub 2019 Jun 11.
The intertwining between mechanics and developmental biology is extensively studied at the shoot apical meristem of land plants. Indeed, plant morphogenesis heavily relies on mechanics; tissue deformations are fueled by turgor-induced forces, and cell mechanosensitivity plays a major regulatory role in this dynamics. Since measurements of forces in growing meristems are still out of reach, our current knowledge relies mainly on theoretical and numerical models. So far, these modeling efforts have been mostly focusing on the epidermis, where aerial organs are initiated. In many models, the epidermis is assimilated to its outermost cell walls and described as a thin continuous shell under pressure, thereby neglecting the inner walls. There is, however, growing experimental evidence suggesting a significant mechanical role of these inner walls. The aim of this work is to investigate the influence of inner walls on the mechanical homeostasis of meristematic tissues. To this end, we simulated numerically the effect of turgor-induced loading, both in realistic flower buds and in more abstract structures. These simulations were performed using finite element meshes with subcellular resolution. Our analysis sheds light on the mechanics of growing plants by revealing the strong influence of inner walls on the epidermis mechanical stress pattern especially in negatively curved regions. Our simulations also display some strong and unsuspected features, such as a correlation between stress intensity and cell size, as well as differential response to loading between epidermal and inner cells. Finally, we monitored the time evolution of the mechanical stresses felt by each cell and its descendants during the early steps of flower morphogenesis.
机械学和发育生物学之间的相互作用在陆地植物的茎尖分生组织中得到了广泛研究。事实上，植物形态发生在很大程度上依赖于力学；组织变形是由膨压诱导的力驱动的，而细胞的机械敏感性在这种动力学中起着主要的调节作用。由于对生长中的分生组织中的力的测量仍然遥不可及，我们目前的知识主要依赖于理论和数值模型。到目前为止，这些建模工作主要集中在表皮上，那里开始形成气生器官。在许多模型中，表皮被等同于其最外层的细胞壁，并被描述为一个在压力下的薄连续壳，从而忽略了内壁。然而，越来越多的实验证据表明这些内壁具有重要的机械作用。本工作的目的是研究内壁对分生组织组织力学稳态的影响。为此，我们使用具有亚细胞分辨率的有限元网格对膨压诱导加载的影响进行了数值模拟，包括在真实的花蕾中和更抽象的结构中。我们的分析通过揭示内壁对表皮机械应力模式的强烈影响，特别是在负曲率区域，揭示了生长中植物的力学特性。我们的模拟还显示了一些强烈而出乎意料的特征，例如，应力强度与细胞大小之间的相关性，以及表皮细胞和内部细胞对加载的不同反应。最后，我们监测了在花形态发生的早期步骤中，每个细胞及其后代感受到的机械应力的时间演化。
