Root Meristem Growth Factor 1 (RGF1) controls root meristem size through reactive oxygen species (ROS) signaling

Purpose: Although five receptors of RGF1 have recently been identified, the downstream signaling mechanism remains unknown. The goal of this study is to elucidate signaling events following RGF1 action. Methods: mRNA profiles of the root meristematic zone from Arabidopsis seedlings with or without RGF1 treatment were generated by deep sequencing, in triplicate. The sequence reads were analyzed using Tophat and DESeq2. The mutants of selected differentially expressed genes were generated for phenotyping. Results: Our study uncovered a series of signaling events following RGF1 action. The RGF1-receptor pathway controls distribution of reactive oxygen species (ROS) along the developmental zones of the Arabidopsis root. We identify a novel transcription factor, RGF1 INDUCIBLE TRANSCRIPTION FACTOR 1 (RITF1), which plays a central role in mediating RGF1 signaling. Manipulating RITF1 expression leads to redistribution of ROS along the root developmental zones. Changes in ROS distribution, in turn, enhance the stability of the PLETHORA2 (PLT2) protein, a master regulator of root stem cells. Conclusions: Our study clearly depicts a signaling cascade initiated by RGF1 and links the RGF1 peptide to ROS regulatory mechanisms. Overall design: mRNA profiles of the root meristematic zone from Arabidopsis seedlings with or without RGF1 treatment were generated by deep sequencing, in triplicate.

目的：尽管目前已鉴定出五种RGF1的受体，但下游信号传导机制仍不明晰。本研究旨在阐明RGF1发挥作用后的信号传导事件。方法：本研究通过深度测序，生成了经RGF1处理与未处理的拟南芥幼苗根分生区的mRNA转录组图谱，每组设置三次生物学重复。序列读取数据采用Tophat与DESeq2进行分析。针对筛选得到的差异表达基因构建突变体，用于表型鉴定。结果：本研究揭示了RGF1发挥作用后的一系列信号传导事件。RGF1-受体通路可调控活性氧（reactive oxygen species, ROS）在拟南芥根发育分区中的分布。我们鉴定出一种新型转录因子——RGF1诱导转录因子1（RGF1 INDUCIBLE TRANSCRIPTION FACTOR 1, RITF1），其在介导RGF1信号传导中发挥核心作用。调控RITF1的表达可导致ROS在根发育分区中重新分布；而ROS分布的改变反过来会增强根干细胞主调控因子PLETHORA2（PLT2）蛋白的稳定性。结论：本研究清晰描绘了RGF1启动的信号级联反应，并将RGF1肽类与ROS调控机制关联起来。整体设计：本研究通过深度测序，生成了经RGF1处理与未处理的拟南芥幼苗根分生区的mRNA转录组图谱，每组设置三次生物学重复。