Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), Versailles, 78000, France.
Université Paris-Saclay, Orsay, 91405, France.
Plant Cell. 2022 Nov 29;34(12):4738-4759. doi: 10.1093/plcell/koac269.
Stem cells play important roles in animal and plant biology, as they sustain morphogenesis and tissue replenishment following aging or injury. In plants, stem cells are embedded in multicellular structures called meristems. The formation of new meristems is essential for the plastic expansion of the highly branched shoot and root systems. In particular, axillary meristems (AMs) that produce lateral shoots arise from the division of boundary domain cells at the leaf base. The CUP-SHAPED COTYLEDON (CUC) genes are major determinants of the boundary domain and are required for AM initiation. However, how AMs get structured and how stem cells become established de novo remain elusive. Here, we show that two NGATHA-LIKE (NGAL) transcription factors, DEVELOPMENT-RELATED PcG TARGET IN THE APEX4 (DPA4)/NGAL3 and SUPPRESSOR OF DA1-1 7 (SOD7)/NGAL2, redundantly repress CUC expression in initiating AMs of Arabidopsis thaliana. Ectopic boundary fate leads to abnormal growth and organization of the AM and prevents de novo stem cell establishment. Floral meristems of the dpa4 sod7 double mutant show a similar delay in de novo stem cell establishment. Altogether, while boundary fate is required for the initiation of AMs, our work reveals how it is later repressed to allow proper meristem establishment and de novo stem cell niche formation.
干细胞在动物和植物生物学中发挥着重要作用，因为它们在衰老或损伤后维持形态发生和组织补充。在植物中，干细胞嵌入称为分生组织的多细胞结构中。新分生组织的形成对于高度分支的芽和根系的可塑性扩展至关重要。特别是，产生侧芽的腋芽分生组织（AMs）是从叶基部的边界域细胞分裂产生的。杯状子叶（CUC）基因是边界域的主要决定因素，是 AM 起始所必需的。然而，AMs 是如何形成的，干细胞是如何从头建立的，仍然难以捉摸。在这里，我们表明两个 NGATHA-LIKE（NGAL）转录因子，发育相关 PcG 靶点在上部 4（DPA4）/NGAL3 和抑制 DA1-1 7（SOD7）/NGAL2，在拟南芥的起始 AM 中冗余抑制 CUC 表达。异位边界命运导致 AM 的异常生长和组织，阻止新的干细胞建立。dpa4 sod7 双突变体的花分生组织也显示出在新的干细胞建立方面的类似延迟。总之，虽然边界命运是 AM 起始所必需的，但我们的工作揭示了它是如何后来被抑制以允许适当的分生组织建立和新的干细胞生态位形成的。
