• During land colonization, plants acquired a range of body plan adaptations, of which the innovation of three‐dimensional (3D) tissues increased organismal complexity and reproductivity. In the moss, Physcomitrella patens, a 3D leafy gametophore originates from filamentous cells that grow in a two‐dimensional (2D) plane through a series of asymmetric cell divisions. Asymmetric cell divisions that coincide with different cell division planes and growth directions enable the developmental switch from 2D to 3D, but insights into the underlying mechanisms coordinating this switch are still incomplete.
• Using 2D and 3D imaging and image segmentation, we characterized two geometric cues, the width of the initial cell and the angle of the transition division plane, which sufficiently distinguished a gametophore initial cell from a branch initial cell. These identified cues were further confirmed in gametophore formation mutants.
• The identification of a fluorescent marker allowed us to successfully predict the gametophore initial cell with > 90% accuracy before morphological changes, supporting our hypothesis that, before the transition division, parental cells of the gametophore initials possess different properties from those of the branch initials.
• Our results suggest that the cell fate decision of the initial cell is determined in the parental cell, before the transition division.

中文翻译：

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几何提示预测小立碗藓由二维增长到三维增长。

• 在土地定居期间，植物获得了一系列的人体计划适应性，其中三维（3D）组织的创新增加了机体的复杂性和繁殖力。在苔藓（Physcomitrella patens）的苔藓中，一个3D多叶类游戏体起源于通过一系列不对称细胞分裂而在二维（2D）平面上生长的丝状细胞。与不同的细胞分裂平面和生长方向一致的不对称细胞分裂可以实现从2D到3D的发育转换，但是对协调这种转换的潜在机制的见解仍然不完整。
• 使用2D和3D成像和图像分割，我们表征了两个几何线索，即初始单元格的宽度和过渡分割平面的角度，这充分区分了配子体初始单元格和分支初始单元格。这些确定的提示在配子体形成突变体中得到进一步证实。
• 荧光标记物的鉴定使我们能够在形态学改变之前以> 90％的准确度成功地预测配子体初始细胞，支持我们的假设，即在过渡分裂之前，配子体初始体的亲代细胞与分支初始体的亲代细胞具有不同的特性。
• 我们的结果表明，初始细胞的细胞命运决定是在过渡分裂之前在亲本细胞中确定的。