Long Yuchen, Smet Wouter, Cruz-Ramírez Alfredo, Castelijns Bas, de Jonge Wim, Mähönen Ari Pekka, Bouchet Benjamin P, Perez Gabino Sanchez, Akhmanova Anna, Scheres Ben, Blilou Ikram
Plant Developmental Biology, Wageningen University, Wageningen 6708PB, The Netherlands Molecular Genetics, Department of Biology, Utrecht University, Utrecht 3581CH, The Netherlands.
Molecular Genetics, Department of Biology, Utrecht University, Utrecht 3581CH, The Netherlands.
Plant Cell. 2015 Apr;27(4):1185-99. doi: 10.1105/tpc.114.132407. Epub 2015 Mar 31.
Plant cells cannot rearrange their positions; therefore, sharp tissue boundaries must be accurately programmed. Movement of the cell fate regulator SHORT-ROOT from the stele to the ground tissue has been associated with transferring positional information across tissue boundaries. The zinc finger BIRD protein JACKDAW has been shown to constrain SHORT-ROOT movement to a single layer, and other BIRD family proteins were postulated to counteract JACKDAW's role in restricting SHORT-ROOT action range. Here, we report that regulation of SHORT-ROOT movement requires additional BIRD proteins whose action is critical for the establishment and maintenance of the boundary between stele and ground tissue. We show that BIRD proteins act in concert and not in opposition. The exploitation of asymmetric redundancies allows the separation of two BIRD functions: constraining SHORT-ROOT spread through nuclear retention and transcriptional regulation of key downstream SHORT-ROOT targets, including SCARECROW and CYCLIND6. Our data indicate that BIRD proteins promote formative divisions and tissue specification in the Arabidopsis thaliana root meristem ground tissue by tethering and regulating transcriptional competence of SHORT-ROOT complexes. As a result, a tissue boundary is not "locked in" after initial patterning like in many animal systems, but possesses considerable developmental plasticity due to continuous reliance on mobile transcription factors.
植物细胞无法重新排列其位置；因此，尖锐的组织边界必须精确编程。细胞命运调节因子SHORT-ROOT从维管束向基本组织的移动与跨组织边界传递位置信息有关。锌指BIRD蛋白JACKDAW已被证明将SHORT-ROOT的移动限制在单层，并且推测其他BIRD家族蛋白可抵消JACKDAW在限制SHORT-ROOT作用范围方面的作用。在此，我们报告SHORT-ROOT移动的调节需要额外的BIRD蛋白，其作用对于维管束和基本组织之间边界的建立和维持至关重要。我们表明BIRD蛋白协同作用而非相互拮抗。对不对称冗余的利用使得两种BIRD功能得以分离：通过核保留和对包括SCARECROW和CYCLIND6在内的关键下游SHORT-ROOT靶标的转录调控来限制SHORT-ROOT的扩散。我们的数据表明，BIRD蛋白通过束缚和调节SHORT-ROOT复合物的转录能力，促进拟南芥根分生组织基本组织中的形态发生分裂和组织特化。结果，与许多动物系统不同，组织边界在初始模式形成后不会“固定”，而是由于持续依赖移动转录因子而具有相当大的发育可塑性。
