Superoxide anion is thought to be a natural by-product with strong oxidizing ability in all living organisms and was recently found to accumulate in plant meristems to maintain stem cells in the shoot and undifferentiated meristematic cells in the root. Here we show that the DNA demethylase repressor of silencing 1 (ROS1) is one of the direct targets of superoxide in stem cells. The Fe–S clusters in ROS1 are oxidized by superoxide to activate its DNA glycosylase/lyase activity. We demonstrate that superoxide extensively participates in the establishment of active DNA demethylation in the Arabidopsis genome and that ARABIDOPSIS RESPONSE REGULATOR 12 acts downstream of ROS1-mediated superoxide signaling to maintain stem cell fate. Our results provide a mechanistic framework for superoxide control of the stem cell niche and demonstrate how redox and DNA demethylation interact to define stem cell fate in plants.

超氧阴离子被认为是在所有生物体中具有很强氧化能力的天然副产物，最近发现它在植物分生组织中积累以维持芽中的干细胞和根中未分化的分生细胞。在这里，我们表明 DNA 脱甲基化酶沉默抑制因子 1 （ROS1） 是干细胞中超氧化物的直接靶标之一。ROS1 中的 Fe-S 簇被超氧化物氧化，以激活其 DNA 糖基化酶/裂解酶活性。我们证明超氧化物广泛参与拟南芥基因组中活性 DNA 去甲基化的建立，并且拟南芥反应调节因子 12 在 ROS1 介导的超氧化物信号传导的下游发挥作用以维持干细胞命运。我们的结果为干细胞生态位的超氧化物控制提供了一个机制框架，并展示了氧化还原和 DNA 去甲基化如何相互作用以定义植物中干细胞的命运。