State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, China.
Curr Biol. 2020 May 18;30(10):1893-1904.e4. doi: 10.1016/j.cub.2020.03.031. Epub 2020 Apr 2.
In plants and animals, self-renewing stem cell populations play fundamental roles in many developmental contexts. Plants differ from most animals in their retained ability to initiate new cycles of growth and development, which relies on the establishment and activity of branch meristems. In seed plants, branching is achieved by stem-cell-containing axillary meristems, which are initiated from a leaf axil meristematic cell population originally detached from the shoot apical meristem. It remains unclear how the meristematic cell fate is maintained. Here, we show that ARABIDOPSISTHALIANAHOMEOBOXGENE1 (ATH1) maintains the meristem marker gene SHOOT MERISTEMLESS (STM) expression in the leaf axil to enable meristematic cell fate maintenance. Furthermore, ATH1 protein interacts with STM protein to form a STM self-activation loop. Genetic and biochemical data suggest that ATH1 anchors STM to activate STM as well as other axillary meristem regulatory genes. This auto-regulation allows the STM locus to remain epigenetically active. Taken together, our findings provide a striking example of a self-activation loop that maintains the flexibility required for stem cell niche re-establishment during organogenesis.
在动植物中，自我更新的干细胞群体在许多发育背景中发挥着基本作用。与大多数动物不同，植物保留了启动新的生长和发育周期的能力，这依赖于分支分生组织的建立和活性。在种子植物中，分支是通过含有干细胞的腋芽分生组织实现的，这些组织是从最初从茎尖分生组织细胞群体中分离出来的叶腋分生组织细胞群体中产生的。分生组织细胞命运是如何维持的仍然不清楚。在这里，我们表明 ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1) 在叶腋中维持分生组织标记基因 SHOOT MERISTEMLESS (STM) 的表达，以维持分生组织细胞命运。此外，ATH1 蛋白与 STM 蛋白相互作用形成 STM 自我激活环。遗传和生化数据表明，ATH1 将 STM 锚定以激活 STM 以及其他腋芽分生组织调节基因。这种自我调节允许 STM 基因座保持表观遗传活性。总之，我们的研究结果提供了一个惊人的自我激活环的例子，该环维持了在器官发生过程中重新建立干细胞生态位所需的灵活性。
