活性氧调控植物根生长的分子机理

ROS (Reactive Oxygen Species) have been recently identified as a second messenger controlling plant root growth. However, the molecular mechanisms and the nature of downstream components of ROS signaling pathway in root development remain mysteries. Recently, we identified two ERF transcription factors, ERFa and ERFb, which were obviously up-regulated after H2O2 treatment. In this project, we use genetic and biochemical methods to identify the direct substrates of ERFa and ERFb using erfa and erfb mutants and their overexpression lines. This project will provides insight into a significant mechanism underlying the role of ERFa and ERFb in controlling root stem cell in Arabidopsis, and also uncovers the roles of ROS in maintaining the balance between cellular proliferation and differentiation in root apical. This project eventually proved important theoretical basis and research methods to reveal the germplasm innovation and yield and quality control mechanism in crops.

近年来的研究结果表明活性氧（reactive oxygen species，ROS）对植物根系的生长发育起到非常重要的作用。但是关于ROS参与调控根生长发育的关键下游应答因子及其分子调控机制，目前知之甚少。本项目以前期筛选到的快速响应H2O2的两个拟南芥ERF转录因子（ERFa、ERFb）的突变体和过表达株系为材料，结合分子生物学、遗传学、转录组测序等方法，寻找ERFa和ERFb的下游关键调控因子，阐明ERFa和ERFb对根伸长及根尖干细胞维持的分子调控机制。本项目预期结果可以深入的阐释ROS对植物根系发育的分子机理，为农作物的产量和品质调控以及种质创新提供重要的科学理论依据。

近年来的研究结果表明活性氧（reactive oxygen species，ROS）对植物根系的生长发育起到非常重要的作用。关于ROS参与调控根生长发育的关键下游应答因子以其分子机制我们知之甚少。为此，我们用1.5 mM H2O2处理5天的拟南芥幼根，进行转录组测序，结合前人已发表的基因芯片的数据，筛选到两个快速响应H2O2的ERF转录因子(ERFa, ERFb)。本课题主要研究ERFa, ERFb调控根尖干细胞微环境的调控机理。我们发现过表达ERFa、ERFb能诱导QC分裂的异常，这些结果表明ERFa、ERFb可能参与植物根尖干细胞维持的调控。我们的研究结果表明，根尖干细胞微环境维持的关键调控因子AP2 转录因子PLT1 (PLETHORA1)和PLT2 (PLETHORA2), GRAS 转录因子比如SCR (SCARECROW) 和 SHR (SHORT ROOT)在过表达ERFa、ERFb中没有明显变化，这些结果暗示ERFa和ERFb通过不依赖于SCR/SHR和PLT1/PLT2的途径来调控根尖干细胞的维持。为了找到ERFa、ERFb的下游调控因子，我们分析整个基因组表达谱系的变化，找到ERFa、ERFb调控的下游基因 （Target 1 和Target 2）。通过ChIP-qPCR和原生质体瞬时转化实验表明ERFa、ERFb直接结合在这两个靶基因的启动子区域，并激活靶基因的表达，另外，这两个靶基因受到H2O2的诱导表达。遗传学分析表明，这两个靶基因位于 ERFa 和 ERFb的下游参与了ROS对根干细胞龛维持和分化。..