Stem cells in plant meristems are kept undifferentiated by signals from surrounding cells and provide the basis for continuous organ formation. In the stem cell organizer of the Arabidopsis thaliana root, the quiescent centre (QC), the WOX5 transcription factor, functions as a central hub in regulating columella stem cell (CSC) homoeostasis. However, the processes mediating WOX5 function are only poorly understood. Here we identify the transcription factor HAN as a central mediator of WOX5-regulated stem cell maintenance. HAN is required for mitotic quiescence of QC and CSC maintenance and is sufficient to induce ectopic stem cells. WOX5 and HAN repress transcription of the differentiation factor gene CDF4 in a coherent feed-forward loop (cFFL), one output of which is the expression of the auxin biosynthesis gene TAA1 and maintenance of auxin response maxima in the organizer. These findings and mathematical modelling provide a mechanistic framework for WOX5 function in the root stem cell niche.

植物分生组织中的干细胞不受来自周围细胞的信号的影响，并为连续器官形成提供基础。在拟南芥根的干细胞组织者中，WOX5 转录因子静态中心 （QC） 作为调节小柱干细胞 （CSC） 匀态的中心枢纽发挥作用。然而，对介导 WOX5 功能的过程知之甚少。在这里，我们将转录因子 HAN 确定为 WOX5 调节干细胞维持的中心介质。HAN 是 QC 的有丝分裂静止和 CSC 维持所必需的，并且足以诱导异位干细胞。WOX5 和 HAN 在相干前馈环 （cFFL） 中抑制分化因子基因 CDF4 的转录，其输出之一是生长素生物合成基因 TAA1 的表达和组织者中生长素反应最大值的维持。这些发现和数学建模为根干细胞生态位中 WOX5 的功能提供了一个机制框架。