Department of Plant Systems Biology, Flanders Institute for Biotechnology, 9052 Ghent, Belgium.
Proc Natl Acad Sci U S A. 2010 Jun 29;107(26):12046-51. doi: 10.1073/pnas.1000672107. Epub 2010 Jun 11.
The stem cell niche in the root meristem is critical for the development of the plant root system. The plant hormone auxin acts as a versatile trigger in many developmental processes, including the regulation of root growth, but its role in the control of the stem cell activity remains largely unclear. Here we show that local auxin levels, determined by biosynthesis and intercellular transport, mediate maintenance or differentiation of distal stem cells in the Arabidopsis thaliana roots. Genetic analysis shows that auxin acts upstream of the major regulators of the stem cell activity, the homeodomain transcription factor WOX5, and the AP-2 transcription factor PLETHORA. Auxin signaling for differentiation of distal stem cells requires the transcriptional repressor IAA17/AXR3 as well as the ARF10 and ARF16 auxin response factors. ARF10 and ARF16 activities repress the WOX5 transcription and restrict it to the quiescent center, where WOX5, in turn, is needed for the activity of PLETHORA. Our investigations reveal that long-distance auxin signals act upstream of the short-range network of transcriptional factors to mediate the differentiation of distal stem cells in roots.
根分生组织中的干细胞龛对于植物根系的发育至关重要。植物激素生长素在许多发育过程中充当多功能触发器，包括调节根生长，但它在控制干细胞活性中的作用在很大程度上仍不清楚。在这里，我们表明局部生长素水平（由生物合成和细胞间运输决定）介导拟南芥根中远端干细胞的维持或分化。遗传分析表明，生长素在干细胞活性的主要调节剂上游起作用，即同源域转录因子 WOX5 和 AP-2 转录因子 PLETHORA。生长素信号转导用于分化远端干细胞需要转录抑制因子 IAA17/AXR3 以及 ARF10 和 ARF16 生长素反应因子。ARF10 和 ARF16 的活性抑制 WOX5 的转录并将其限制在静止中心，WOX5 反过来又需要 PLETHORA 的活性。我们的研究表明，长距离生长素信号在转录因子的短程网络上游起作用，以介导根中远端干细胞的分化。
