Direct roles of SPEECHLESS in the specification of stomatal self-renewing cells [ChIP-Seq]. Arabidopsis thaliana

Lineage-specific stem cells are critical for the production and maintenance of specific cell types and tissues in multicellular organisms. In higher plants, the initiation and proliferation of stomatal stem cells is controlled by the basic helix-loop-helix transcription factor SPEECHLESS (SPCH). The stomatal stem cells and SPCH, which represent an innovation in seed plants, allow flexibility in the production of stomata, but how SPCH generates these stem cells is unclear. Here, we developed a highly sensitive chromatin immunoprecipitation (ChIP) assay and profiled the cell-type specific genome-wide targets of Arabidopsis SPCH in vivo. We found that SPCH directly controls key and novel regulators that drive cell fate and asymmetric cell divisions and enhances responsiveness to cell-cell communication. Our results provide molecular insights on how a master transcription factor generates an adult stem cell lineage that contributes to the success of land plants. Overall design: Genome-wide identification of SPCH binidng sites

谱系特异性干细胞（lineage-specific stem cells）对于多细胞生物体内特定细胞类型与组织的产生与维持至关重要。在高等植物中，气孔干细胞（stomatal stem cells）的起始与增殖受碱性螺旋-环-螺旋转录因子SPEECHLESS（SPCH）调控。气孔干细胞与SPCH作为种子植物的演化创新，使得气孔的产生具备灵活性，但SPCH如何生成此类干细胞的机制仍不明晰。本研究开发了一种高灵敏度的染色质免疫共沉淀（chromatin immunoprecipitation, ChIP）实验方法，并在体内绘制了拟南芥SPCH的细胞类型特异性全基因组结合靶标图谱。研究发现，SPCH可直接调控驱动细胞命运与不对称细胞分裂的关键及新型调控因子，并增强细胞通讯响应能力。本研究结果为这类核心转录因子如何生成助力陆地植物演化成功的成体干细胞谱系提供了分子层面的见解。整体实验设计：SPCH结合位点的全基因组鉴定