The cytoskeleton plays a key role in establishing robust cell shape. In animals, it is well established that cell shape can also influence cytoskeletal organization. Cytoskeletal proteins are well conserved between animal and plant kingdoms; nevertheless, because plant cells exhibit major structural differences to animal cells, the question arises whether the plant cytoskeleton also responds to geometrical cues. Recent numerical simulations predicted that a geometry-based rule is sufficient to explain the microtubule (MT) organization observed in cells. Due to their high flexural rigidity and persistence length of the order of a few millimeters, MTs are rigid over cellular dimensions and are thus expected to align along their long axis if constrained in specific geometries. This hypothesis remains to be tested in cellulo. Here, we explore the relative contribution of geometry to the final organization of actin and MT cytoskeletons in single plant cells of Arabidopsis thaliana. We show that the cytoskeleton aligns with the long axis of the cells. We find that actin organization relies on MTs but not the opposite. We develop a model of self-organizing MTs in three dimensions, which predicts the importance of MT severing, which we confirm experimentally. This work is a first step toward assessing quantitatively how cellular geometry contributes to the control of cytoskeletal organization in living plant cells.

细胞骨架在建立稳健的细胞形状方面发挥着关键作用。在动物中，众所周知，细胞形状也会影响细胞骨架组织。细胞骨架蛋白在动物界和植物界之间保存完好；然而，由于植物细胞与动物细胞表现出重大的结构差异，因此出现了植物细胞骨架是否也对几何线索做出反应的问题。最近的数值模拟预测，基于几何的规则足以解释在细胞中观察到的微管（MT）组织。由于其高抗弯刚度和几毫米量级的持久长度，MT 在细胞尺寸上是刚性的，因此如果受到特定几何形状的约束，预计会沿其长轴对齐。这一假设仍有待在大提琴中进行检验。在这里，我们探讨了几何结构对拟南芥单个植物细胞中肌动蛋白和 MT 细胞骨架最终组织的相对贡献。我们发现细胞骨架与细胞的长轴对齐。我们发现肌动蛋白的组织依赖于 MT，但反之则不然。我们开发了一个三维自组织 MT 模型，该模型预测了 MT 切断的重要性，并通过实验证实了这一点。这项工作是定量评估细胞几何形状如何有助于控制活植物细胞中的细胞骨架组织的第一步。