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首页> 外文学位 >Functionally characterizing transcription factors LC from Zea mays and NTAN2 from Nicotiana tabacum and exploring their roles in combinatorial regulation of anthocyanin biosynthesis.
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Functionally characterizing transcription factors LC from Zea mays and NTAN2 from Nicotiana tabacum and exploring their roles in combinatorial regulation of anthocyanin biosynthesis.

机译：在功能上表征玉米的转录因子LC和烟草的NTAN2，并探讨它们在花色苷生物合成的组合调节中的作用。

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摘要

Anthocyanins are important plant secondary metabolites and their synthesis is regulated by a combination of basic helix-loop-helix transcription factor (bHLH TF), MYB TF and WD40 protein.;Lc is a key regulator of anthocyanin pathway in maize. Despite possessing a conserved bHLH sequence, Lc is incapable of binding the E-box sequence (CANNTG), a common DNA motif recognized by bHLH domains. We demonstrated that the isolated Lc bHLH domain has the ability to form a homodimer and specifically binds to G-box (CACGTG). The dimerization is affected by a leucine zipper-like (LZL) structure adjacently. Another dimer-forming, ACT-like domain at the C-terminal of Lc suppresses the DNA-binding potential of bHLH, providing a possible explanation for Lc's inability to bind E-box sequence. The dimerization mediated by the bHLH domain of Lc inhibits its interaction with maize RIF1, a chromatin modification factor. Lc can activate a G-box/luciferase-reporter in vivo and both the bHLH and ACT-like domains are necessary for the activation. Our study demonstrating the cooperation of multiple dimer interfaces underscores a unique mechanism of combinatorial transcriptional regulation by the Lc-like bHLH TFs.;Ectopic expression of Lc in tobacco results in increased anthocyanin production in the reproductive tissues, suggesting the presence of a reproductive tissue-specific MYB TF that interacts with Lc in anthocyanin gene activation. We isolated NtAn2, a gene encoding an R2R3-MYB TF that shares high sequence homology with other known flavonoid-related MYB TFs and is expressed specially in developing flowers. Constitutive expression of NtAn2 induces whole plant anthocyanin production in tobacco in which both subsets of early and late flavonoid pathway genes are upregulated. Suppression of NtAn2 by RNAi resulted in a white-flowered phenotype and the inhibition of the late pathway genes. These results suggest NtAn2 is a key gene controlling anthocyanin production in reproductive tissues of tobacco.;In addition, in order to create a gene expression vector that induces anthocyanin production in various plant species, we generated a chimeric TF (Lc-NtAn2), in which Lc is fused with NtAn2 by a peptide linker. Constitutive expression of the Lc-NtAn2 in Arabidopsis led to anthocyanin accumulation in multiple tissues and upregulation of multiple anthocyanin pathway genes.;Keywords. Basic Helix-loop-helix (bHLH) Transcription Factor, R2R3-MYB Transcription Factor, Chimeric Transcription Factor, Anthocyanin biosynthesis, Transcriptional Regulation
机译：花色苷是重要的植物次生代谢产物，其合成受碱性螺旋-环-螺旋转录因子（bHLH TF），MYB TF和WD40蛋白的调节。Lc是玉米中花色苷途径的关键调节剂。尽管Lc具有保守的bHLH序列，但Lc无法结合E-box序列（CANNTG），E-box序列是bHLH域识别的常见DNA基序。我们证明了孤立的LC bHLH域具有形成同型二聚体的能力，并特异性结合G-box（CACGTG）。二聚化受到邻近的亮氨酸拉链状（LZL）结构的影响。 Lc的C端另一个形成二聚体的ACT样结构域抑制bHLH的DNA结合潜力，为Lc无法结合E-box序列提供了可能的解释。 Lc的bHLH域介导的二聚化抑制了它与玉米RIF1（一种染色质修饰因子）的相互作用。 Lc可以在体内激活G-box /荧光素酶报告基因，而bHLH和ACT样结构域都是激活所必需的。我们的研究证明了多个二聚体界面的合作强调了Lc样bHLH TF组合转录调控的独特机制。Lc在烟草中的异位表达导致生殖组织中花青素的产生增加，表明存在生殖组织-在花青素基因激活中与Lc相互作用的特定MYB TF。我们分离了NtAn2，这是一个编码R2R3-MYB TF的基因，该基因与其他已知的类黄酮相关MYB TF具有高度的序列同源性，并特别在发育中的花中表达。 NtAn2的组成型表达诱导了烟草中整个植物花色苷的产生，其中早期和晚期类黄酮途径基因的两个子集均被上调。 RNAi对NtAn2的抑制导致白花的表型和后期通路基因的抑制。这些结果表明NtAn2是控制烟草生殖组织中花青素生成的关键基因。此外，为了创建诱导多种植物花青素生成的基因表达载体，我们在烟草中产生了嵌合TF（Lc-NtAn2）。 Lc通过肽接头与NtAn2融合。 Lc-NtAn2在拟南芥中的组成型表达导致花青素在多个组织中的积累和多个花色苷途径基因的上调。基本螺旋-环-螺旋（bHLH）转录因子，R2R3-MYB转录因子，嵌合转录因子，花色苷生物合成，转录调控

著录项

  • 作者

    Kong, Que.;

  • 作者单位

    University of Kentucky.;

  • 授予单位 University of Kentucky.;
  • 学科 Agriculture Plant Culture.;Biology Plant Physiology.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 120 p.
  • 总页数 120
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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