Division of Applied Life Science (BK21 Program); Plant Molecular Biology and Biotechnology Research Center (PMBBRC); Gyeongsang National University; Jinju, Korea.
Plant Signal Behav. 2013 May;8(5):e24139. doi: 10.4161/psb.24139. Epub 2013 Mar 7.
One of the strategies that plants utilize to adapt to fluctuating soil nutrient levels is rapid reprogramming of transcriptional regulation via cell signaling mechanisms. Higher plants exposed to ammonium undergo modulation of a broad spectrum of gene expression. However, regulation of the transcriptional mechanisms underlying ammonium-mediated gene expression is poorly understood. We identified a transcriptional regulator, indeterminate domain 10 (IDD10), whose mutants exhibited an ammonium-hypersensitive root growth defect. To elucidate the molecular relationship between IDD10 and ammonium-mediated gene expression, ammonium-responsive genes were examined in mutants and overexpressors of IDD10. Among the key ammonium uptake and assimilation genes, AMT1;2 (ammonium transporter 1;2) and GDH2 (glutamate dehydrogenase 2) significantly depend on IDD10 expression levels for ammonium-mediated induction. Extensive molecular analysis revealed that IDD10 directly binds to the promoter of AMT1;2 and the fifth intron of GDH2 genes via the core sequence TTTGTC(C)/(G). Transcriptome analysis with root tissues identified many ammonium-inducible genes whose expression was increased by IDD10. Half of them contained potential IDD10-binding motifs in their promoters. This study determined that IDD10 is a transcriptional activator involved in nitrogen regulatory circuits that control a broad spectrum of gene expression, which might influence root growth in rice.
植物适应土壤养分波动的策略之一是通过细胞信号机制快速重新编程转录调控。暴露于铵态氮的高等植物会对广泛的基因表达进行调节。然而，对于铵介导的基因表达的转录机制的调节知之甚少。我们鉴定了一个转录调节因子，不定域 10（IDD10），其突变体表现出铵敏感的根生长缺陷。为了阐明 IDD10 与铵介导的基因表达之间的分子关系，我们在 IDD10 的突变体和过表达体中检查了铵响应基因。在关键的铵吸收和同化基因中，AMT1;2（铵转运蛋白 1;2）和 GDH2（谷氨酸脱氢酶 2）显著依赖于 IDD10 表达水平来进行铵诱导。广泛的分子分析表明，IDD10 通过核心序列 TTTGTC(C)/(G)直接与 AMT1;2 和 GDH2 基因的启动子和第五内含子结合。对根组织的转录组分析鉴定出许多铵诱导基因，其表达受 IDD10 增加。其中一半在其启动子中含有潜在的 IDD10 结合基序。本研究确定 IDD10 是一种参与氮调节回路的转录激活因子，该回路控制广泛的基因表达，这可能会影响水稻的根生长。
