Center for Organismal Studies (COS), University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.
Department of Plant and Microbial Biology, University of Zurich, 8008 Zurich, Switzerland.
Curr Biol. 2019 Aug 5;29(15):2443-2454.e5. doi: 10.1016/j.cub.2019.06.039. Epub 2019 Jul 18.
How plant cells re-establish differential growth to initiate organs is poorly understood. Morphogenesis of lateral roots relies on the asymmetric cell division of initially symmetric founder cells. This division is preceded by the tightly controlled asymmetric radial expansion of these cells. The cellular mechanisms that license and ensure the coordination of these events are unknown. Here, we quantitatively analyze microtubule and F-actin dynamics during lateral root initiation. Using mutants and pharmacological and tissue-specific genetic perturbations, we show that dynamic reorganization of both microtubule and F-actin networks is necessary for the asymmetric expansion of the founder cells. This cytoskeleton remodeling intertwines with auxin signaling in the pericycle and endodermis in order for founder cells to acquire a basic polarity required for initiating lateral root development. Our results reveal the conservation of cell remodeling and polarization strategies between the Arabidopsis zygote and lateral root founder cells. We propose that coordinated, auxin-driven reorganization of the cytoskeleton licenses asymmetric cell growth and divisions during embryonic and post-embryonic organogenesis.
植物细胞如何重新建立差异生长以启动器官尚不清楚。侧根的形态发生依赖于最初对称的起始细胞的不对称细胞分裂。这种分裂之前是这些细胞的紧密控制的不对称径向扩张。许可和确保这些事件协调的细胞机制尚不清楚。在这里，我们在侧根起始过程中定量分析微管和 F-肌动蛋白动力学。使用突变体和药理学及组织特异性遗传干扰，我们表明微管和 F-肌动蛋白网络的动态重排对于起始细胞的不对称扩张是必要的。这种细胞骨架重塑与周细胞和内皮层中的生长素信号交织在一起，以便起始细胞获得启动侧根发育所需的基本极性。我们的结果揭示了拟南芥合子和侧根起始细胞之间细胞重塑和极化策略的保守性。我们提出，协调的、生长素驱动的细胞骨架重组在胚胎和胚胎后器官发生过程中许可不对称细胞生长和分裂。
