In angiosperms, a negative feedback pathway involving CLAVATA3 (CLV3) peptide and WUSCHEL transcription factor maintains the stem-cell population in the shoot apical meristem and is central for continued shoot growth and organogenesis. An intriguing question is how this cell-signalling system was established during the evolution of land plants. On the basis of two recent studies on CLV3/ESR-related (CLE) genes, this paper proposes a model for the evolution of meristem zonation. The model suggests that a stem-cell-limiting CLV3 pathway is derived from stem-cell-promoting CLE pathways conserved in land pants by gene duplication in the angiosperm lineage. The model can be examined in the future by genomic and developmental studies on diverse plant species.

 摘 要 

在被子植物中，一个涉及到CLV3和WUS的负反馈途径维持着茎尖分生组织中的干细胞群，对于被子植物持续的茎生长和器官发生至关重要。一个有趣的问题是该细胞信号转导系统是如何在陆地植物的演化过程中建立起来的。基于最近有关CLE基因的两份研究报道，本文提出了一个陆地植物分生区演化的模型。该模型显示限制干细胞的CLV3途径起源于陆地植物中保守的促进干细胞CLE途径，通过被子植物支系中的基因复制事件获得。未来可以通过对不同植物物种的基因组学和发育生物学研究来检验该模型。

 Yuki Hirakawa