Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice and Arabidopsis[C][W][OA]
Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice and Arabidopsis[C][W][OA]
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DOI：
10.1105/tpc.109.070441
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发表时间：
2009-12
期刊：
影响因子：
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通讯作者：
Li-Ying Zhang;Ming-Yi Bai;Jinxia Wu;Jiachen Zhu;Hao Wang;Zhiguo Zhang;Wenfei Wang;Yu Sun
中科院分区：
文献类型：
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作者：
Li-Ying Zhang;Ming-Yi Bai;Jinxia Wu;Jiachen Zhu;Hao Wang;Zhiguo Zhang;Wenfei Wang;Yu Sun
在水稻（Oryza sativa）中，油菜素类固醇（BR）诱导叶片接头近轴侧的细胞伸长，从而促进叶片弯曲。我们鉴定了一种水稻突变体 (ili1-D)，其表现出与 BR 处理相似的叶片倾斜表型增加。 ili1-D 突变体过表达与拟南芥多效唑抗性 1 (PRE1) 和人类 DNA 结合蛋白抑制剂同源的 HLH 蛋白。 ILI1 的过表达和 RNA 干扰抑制分别增加和降低水稻层状倾斜度，证实了 ILI1 在叶片弯曲中的积极作用。 ILI1 和 PRE1 与碱性螺旋-环-螺旋 (bHLH) 蛋白 IBH1（ILI1 结合 bHLH）相互作用，IBH1 的过度表达导致水稻叶片直立，拟南芥叶片矮化。在拟南芥中，ILI1 或 PRE1 的过度表达会增加细胞伸长并抑制 IBH1 过度表达引起的矮化表型。因此，ILI1 和 PRE1 可能通过异二聚化使抑制性 bHLH 转录因子失活。 BR 增加 ILI1 和 PRE1 的 RNA 水平，但通过转录因子 BZR1 抑制 IBH1。空间和时间表达模式支持 ILI1 在层关节弯曲中的作用以及 PRE1/At IBH1 在年轻器官生长到生长停滞的转变中的作用。这些结果证明了 BR 通过一对拮抗 HLH/bHLH 转录因子（在拟南芥和水稻中作用于 BZR1 下游）调节植物发育的保守机制。
In rice (Oryza sativa), brassinosteroids (BRs) induce cell elongation at the adaxial side of the lamina joint to promote leaf bending. We identified a rice mutant (ili1-D) showing an increased lamina inclination phenotype similar to that caused by BR treatment. The ili1-D mutant overexpresses an HLH protein homologous to Arabidopsis thaliana Paclobutrazol Resistance1 (PRE1) and the human Inhibitor of DNA binding proteins. Overexpression and RNA interference suppression of ILI1 increase and reduce, respectively, rice laminar inclination, confirming a positive role of ILI1 in leaf bending. ILI1 and PRE1 interact with basic helix-loop-helix (bHLH) protein IBH1 (ILI1 binding bHLH), whose overexpression causes erect leaf in rice and dwarfism in Arabidopsis. Overexpression of ILI1 or PRE1 increases cell elongation and suppresses dwarf phenotypes caused by overexpression of IBH1 in Arabidopsis. Thus, ILI1 and PRE1 may inactivate inhibitory bHLH transcription factors through heterodimerization. BR increases the RNA levels of ILI1 and PRE1 but represses IBH1 through the transcription factor BZR1. The spatial and temporal expression patterns support roles of ILI1 in laminar joint bending and PRE1/At IBH1 in the transition from growth of young organs to growth arrest. These results demonstrate a conserved mechanism of BR regulation of plant development through a pair of antagonizing HLH/bHLH transcription factors that act downstream of BZR1 in Arabidopsis and rice.