Department of Biology and Biotechnologies "C. Darwin," Laboratory of Functional Genomics and Proteomics of Model Systems, University of Rome "Sapienza", via dei Sardi, 70, 00185 Rome, Italy.
Computational Developmental Biology Group, Department of Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
Dev Cell. 2020 May 18;53(4):431-443.e23. doi: 10.1016/j.devcel.2020.04.004. Epub 2020 May 7.
During organogenesis, coherent organ growth arises from spatiotemporally coordinated decisions of individual cells. In the root of Arabidopsis thaliana, this coordination results in the establishment of a division and a differentiation zone. Cells continuously move through these zones; thus, a major question is how the boundary between these domains, the transition zone, is formed and maintained. By combining molecular genetics with computational modeling, we reveal how an auxin/PLETHORA/ARR-B network controls these dynamic patterning processes. We show that after germination, cell division causes a drop in distal PLT2 levels that enables transition zone formation and ARR12 activation. The resulting PLT2-ARR12 antagonism controls expansion of the division zone (the meristem). The successive ARR1 activation antagonizes PLT2 through inducing the cell-cycle repressor KRP2, thus setting final meristem size. Our work indicates a key role for the interplay between cell division dynamics and regulatory networks in root zonation and transition zone patterning.
在器官发生过程中，单个细胞的时空协调决策产生了协调一致的器官生长。在拟南芥的根中，这种协调导致了分裂和分化区的建立。细胞不断地在这些区域中移动；因此，一个主要的问题是这些域之间的边界，即过渡区，是如何形成和维持的。通过将分子遗传学与计算建模相结合，我们揭示了生长素/PLT2/PLETHORA/ARR-B 网络如何控制这些动态模式形成过程。我们表明，在发芽后，细胞分裂导致远端 PLT2 水平下降，从而使过渡区形成和 ARR12 激活。由此产生的 PLT2-ARR12 拮抗作用控制着分裂区（分生组织）的扩张。随后的 ARR1 激活通过诱导细胞周期抑制剂 KRP2 拮抗 PLT2，从而确定最终的分生组织大小。我们的工作表明，细胞分裂动力学和调控网络之间的相互作用在根分区和过渡区模式形成中起着关键作用。
