Echevarría Clara, Desvoyes Bénédicte, Marconi Marco, Franco-Zorrilla José Manuel, Lee Laura, Umeda Masaaki, Sablowski Robert, Birnbaum Kenneth D, Wabnik Krzysztof, Gutierrez Crisanto
Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain.
Centro de Biotecnología y Genómica de Plantas, UPM-INIA-CSIC, Pozuelo de Alarcón (Madrid), Spain.
Nat Plants. 2025 Sep 18. doi: 10.1038/s41477-025-02109-3.
Organogenesis relies on the coordination of cell proliferation with developmental programs. In meristems, where new plant organs initiate, the cell proliferation potential depends on stem cell regulators, but the mechanisms linking their local activity with the cell cycle machinery remain unknown. Here we show a positional gradient of G1 duration in the Arabidopsis root meristem spanning from ~2 h near the meristem boundary to more than 20 h in the early stem cell derivatives. Mutations in the stem cell regulatory PLETHORA (PLT) genes and the cell cycle RETINOBLASTOMA-RELATED 1 gene shortened G1 duration, abolishing the G1 duration gradient, whereas PLT2 overexpression increased G1 duration. Data-driven computer modelling supported the presence of an incoherent feed-forward loop. We found that PLT genes are drivers with simultaneous and opposing roles in maintaining stem cell activity and inhibiting G1 progression through a cascade involving the CDK inhibitor KRP5, a PLT target and RETINOBLASTOMA-RELATED 1. The G1 duration gradient is developmentally regulated and established after the emergence of lateral roots from the primary root and correlates with increased tolerance to genome damage. Our study establishes a previously undescribed proximal-distal G1 duration gradient during root development that is shaped by the balanced activity of stem cell maintenance and cell cycle regulators.
器官发生依赖于细胞增殖与发育程序的协调。在新的植物器官起始的分生组织中，细胞增殖潜能取决于干细胞调节因子，但其局部活性与细胞周期机制之间的联系仍不清楚。在这里，我们展示了拟南芥根分生组织中G1期持续时间的位置梯度，从分生组织边界附近的约2小时到早期干细胞衍生物中的超过20小时。干细胞调节基因多胚形成（PLETHORA，PLT）和细胞周期视网膜母细胞瘤相关1基因的突变缩短了G1期持续时间，消除了G1期持续时间梯度，而PLT2过表达增加了G1期持续时间。数据驱动的计算机建模支持存在非相干前馈环。我们发现，PLT基因在通过涉及细胞周期蛋白依赖性激酶抑制剂KRP5（一个PLT靶点）和视网膜母细胞瘤相关1的级联反应维持干细胞活性和抑制G1期进程中具有同时且相反的作用。G1期持续时间梯度在侧根从主根出现后受到发育调控并建立，且与对基因组损伤的耐受性增加相关。我们的研究在根发育过程中建立了一个之前未描述的近端 - 远端G1期持续时间梯度，该梯度由干细胞维持和细胞周期调节因子的平衡活性塑造。
