Synergistic control of auxin mediated transcription by ARF and C/S1 bZIP transcription factors

为了维持植物的最佳生长，生长素调节的转录根据植物信号进行调节。本项目研究信号整合到生长素介导的转录模式中。以拟南芥GH3.3启动子为模型，我们可以证明生长素反应元件（AuxinResponseElements，MAREs）、G-BOX相关元件（GREs）和MYB反应元件（MYBResponsiveElements，MREs）在生长素介导的转录中相互作用。生长素反应因子（ARF）通过GREs介导生长素反应，而GREs和MREs作为定量元件。该项目的重点是S1组碱性亮氨酸拉链（bZIP）转录因子AtbZIP 2，AtbZIP 11和AtbZIP 44的影响，这些转录因子通过与GRES结合来调节生长素反应。雌激素二醇诱导的增益和损失的功能的转基因植物的方法将被用来研究这些bZIPs生长素调控的转录和其在体内结合到各自的启动子的影响。根据bZIP的表达，将研究典型的生长素反应，如侧根的发生、根毛的形成和向重力反应。由于C/S1 bZIP网络调节初级代谢以响应能量应激，我们假设GRE/bZIP模块作为“流变体”起作用，其提供平衡生长素介导的生长反应与细胞能量状态的手段。

In order to sustain optimal plant growth, auxin regulated transcription is adjusted according to environ-mental signals. This project studies the integration of signals into auxin-mediated transcriptional pat-terns. Using the Arabidopsis GH3.3 promoter as a model, we could demonstrate that AUXIN RESPONSE ELEMENTS (AuxREs), G-BOX RELATED ELEMENTS (GREs) and MYB RESPONSIVE ELEMENTS (MREs) cooperate in auxin-mediated transcription. Whereas AUXIN RESPONSE FACTORS (ARFs) mediate auxin-responsiveness via AuxREs, GREs and MREs act as quantitative elements. This project focuses on the impact of the group S1 basic leucine zipper (bZIP) transcription factors AtbZIP2, AtbZIP11 and AtbZIP44 which modulate auxin responses via binding to GREs. Estra-diol-induced gain- and loss-of function approaches in transgenic plants will be used to study the impact of these bZIPs on auxin-regulated transcription and its in vivo binding to the respective promoters. De-pending on bZIP expression, typical auxin responses such as initiation of lateral roots, root hair forma-tion and gravitropic responses will be studied. As C/S1 bZIP network modulates primary metabolism in response to energy stress, we postulate that the GRE/bZIP module functions as a “rheostate” which provides means to balance auxin-mediated growth responses with the energy status of the cell.