The transcription factor RSG regulates negative feedback of NtGA20ox1 encoding GA 20-oxidase
The transcription factor RSG regulates negative feedback of NtGA20ox1 encoding GA 20-oxidase
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DOI：
10.1111/j.1365-313x.2010.04215.x
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发表时间：
2010-06-01
期刊：
影响因子：
7.2
通讯作者：
Takahashi, Yohsuke
中科院分区：
文献类型：
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作者：
Fukazawa, Jutarou;Nakata, Masaru;Takahashi, Yohsuke
赤霉素(GAs)是一种在植物整个生命周期中调节生长发育的植物激素。RSG是一种含有碱性亮氨酸拉链结构域的烟草转录激活剂，它通过GA生物合成酶来调节内源GAs的含量。负反馈有助于GA水平的动态平衡。以往的研究表明，RSG直接或间接参与了编码GA20-氧化酶的NtGA20ox1的GA负反馈。利用转基因烟草植株，我们已经确定了一个负责NtGA20ox1反馈调控的顺式作用区域。该区域包含RSG结合序列。RSG结合序列的突变消除了转基因植物中NtGA20ox1的负反馈。染色质免疫沉淀(ChIP)分析表明，随着GA水平的降低，RSG在体内与NtGA20ox1启动子结合，这种结合在GA处理后3h内被取消。此外，GA水平的降低促进了NtGA20ox1启动子中活性组蛋白标记的修饰。我们的结果表明，RSG通过直接与NtGA20ox1启动子结合，在GAS的动态平衡中发挥作用。
P>Gibberellins (GAs) are phytohormones that regulate growth and development throughout the life cycle of plants. RSG (REPRESSION OF SHOOT GROWTH) is a tobacco (Nicotiana tabacum) transcriptional activator with a basic leucine zipper domain that regulates the endogenous amount of GAs by control of GA biosynthetic enzymes. Negative feedback contributes to homeostasis of the GA levels. Previous studies suggested that RSG is directly or indirectly involved in the GA negative feedback of NtGA20ox1 encoding GA 20-oxidase. Using transgenic tobacco plants, we have identified a cis-acting region that is responsible for the feedback regulation of NtGA20ox1. This region contains an RSG-binding sequence. A mutation in the RSG-binding sequence abolished negative feedback of NtGA20ox1 in transgenic plants. Chromatin immunoprecipitation (ChIP) assays showed that RSG binds to the NtGA20ox1 promoter in vivo in response to a decrease in GA levels, and that this binding is abolished within 3 h after GA treatment. Furthermore, decreases in GA levels promote modifications of active histone marks in the promoter of NtGA20ox1. Our results suggest that RSG plays a role in the homeostasis of GAs through direct binding to the NtGA20ox1 promoter.