Saltini Marco, Deinum Eva E
Mathematical and Statistical Methods (Biometris), Wageningen University, Wageningen, The Netherlands.
PLoS Comput Biol. 2025 Sep 8;21(9):e1013282. doi: 10.1371/journal.pcbi.1013282. eCollection 2025 Sep.
Many plant cell functions, including cell morphogenesis and anisotropic growth, rely on the self-organisation of cortical microtubules into aligned arrays with the correct orientation. An important ongoing debate is how cell geometry, wall mechanical stresses, and other internal and external cues are integrated to determine the orientation of the cortical array. Here, we demonstrate that microtubule-based nucleation can markedly shift the balance between these often competing directional cues. For this, we developed a novel, more realistic model for microtubule-based nucleation in the simulation platform CorticalSim, which avoids the longstanding inhomogeneity problem stemming from previous, less realistic models for microtubule-based nucleation. We show that microtubule-based nucleation increases the sensitivity of the array to cell geometry, and extends the regime of spontaneous alignment compared to isotropic nucleation. In the case of cylindrical cell shapes, we show that this translates into a strong tendency to align in the transverse direction rather than along the vertical axis, and this is robust against small directional cues favouring the longitudinal direction. Comparing various cylinders and boxes, we show that different nucleation mechanisms result in different preferred array orientations, with the largest differences on cylinders. Our model provides a powerful tool for investigating how plant cells integrate multiple biases to orient their cortical arrays, offering new insights into the biophysical mechanisms underlying cell shape and growth.
许多植物细胞功能，包括细胞形态发生和各向异性生长，都依赖于皮质微管自组织成具有正确取向的排列阵列。一个重要的持续争论是细胞几何形状、细胞壁机械应力以及其他内部和外部线索如何整合以确定皮质阵列的取向。在这里，我们证明基于微管的成核可以显著改变这些经常相互竞争的方向线索之间的平衡。为此，我们在模拟平台CorticalSim中开发了一种新颖、更现实的基于微管成核的模型，该模型避免了先前不太现实的基于微管成核模型所产生的长期不均匀性问题。我们表明，基于微管的成核增加了阵列对细胞几何形状的敏感性，并且与各向同性成核相比，扩展了自发排列的范围。在圆柱形细胞形状的情况下，我们表明这转化为在横向而不是沿垂直轴排列的强烈趋势，并且这对于有利于纵向的小方向线索具有鲁棒性。比较各种圆柱体和盒子，我们表明不同的成核机制导致不同的首选阵列取向，在圆柱体上差异最大。我们的模型为研究植物细胞如何整合多种偏差以定向其皮质阵列提供了一个强大的工具，为细胞形状和生长背后的生物物理机制提供了新的见解。
