The rice transcription factor IDEF1 is essential for the early response to iron deficiency, and induces vegetative expression of late embryogenesis abundant genes
The rice transcription factor IDEF1 is essential for the early response to iron deficiency, and induces vegetative expression of late embryogenesis abundant genes
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DOI：
10.1111/j.1365-313x.2009.04015.x
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发表时间：
2009-12-01
期刊：
影响因子：
7.2
通讯作者：
Nishizawa, Naoko K.
中科院分区：
文献类型：
--
作者：
Kobayashi, Takanori;Itai, Reiko Nakanishi;Nishizawa, Naoko K.
高等植物通过调节铁(Fe)相关基因的表达来维持铁的动态平衡。转录因子IDEF1通过识别缺铁响应顺式作用元件IDE1中的CATGC序列来调节水稻对缺铁的反应。为了更详细地研究IDEF1的功能，我们分析了诱导或抑制IDEF1表达的转基因水稻植株对铁缺乏的反应。水培缺铁处理表明，与IDEF1诱导的植株相比，IDEF1基因敲除植株对早期缺铁敏感。定量逆转录聚合酶链式反应分析表明，在铁饥饿开始后，IDEF1的表达水平与铁利用相关基因OsIRO2、OsYSL15、OsIRT1、OsYSL2、OsNAS1、OsNAS2、OsNAS3和OsDMAS1的诱导水平呈正相关。然而，这种由IDEF1介导的整体反式激活在随后的阶段变得不那么明显。基因芯片和电子芯片分析表明，受IDEF1正调控的基因，特别是在早期阶段，在近端的启动子区域表现出CATGC和IDE1样元件的过度表达。这些结果表明存在对缺铁的早期和随后的反应，前者更具体地需要IDEF1。受IDEF1调控的基因启动子的近端区域也显示了RY元件(CATGCA)的丰富，该元件在种子成熟过程中调节基因的表达。在缺铁的根和/或叶中，包括Osem在内的几个编码胚胎发育后期丰富蛋白的基因以IDEF1依赖的方式被诱导表达，这表明种子成熟相关基因可能在缺铁营养器官中发挥作用。
P>Higher plants maintain iron homeostasis by regulating the expression of iron (Fe)-related genes in accordance with Fe availability. The transcription factor IDEF1 regulates the response to Fe deficiency in Oryza sativa (rice) by recognizing CATGC sequences within the Fe deficiency-responsive cis-acting element IDE1. To investigate the function of IDEF1 in detail, we analyzed the response to Fe deficiency in transgenic rice plants exhibiting induced or repressed IDEF1 expression. Fe-deficiency treatment in hydroponic culture revealed that IDEF1 knock-down plants are susceptible to early-stage Fe deficiency, in contrast to IDEF1-induced plants. Time-course expression analyses using quantitative reverse-transcriptase PCR revealed that the IDEF1 expression level was positively correlated with the level of induction of the Fe utilization-related genes OsIRO2, OsYSL15, OsIRT1, OsYSL2, OsNAS1, OsNAS2, OsNAS3 and OsDMAS1, just after the onset of Fe starvation. However, this overall transactivation mediated by IDEF1 became less evident in subsequent stages. Microarray and in-silico analyses revealed that genes positively regulated by IDEF1, especially at the early stage, exhibit over-representation of CATGC and IDE1-like elements within the proximal promoter regions. These results indicate the existence of early and subsequent responses to Fe deficiency, with the former requiring IDEF1 more specifically. Proximal regions of IDEF1-regulated gene promoters also showed enrichment of RY elements (CATGCA), which regulate gene expression during seed maturation. The expression of several genes encoding late embryogenesis abundant proteins, including Osem, was induced in Fe-deficient roots and/or leaves in an IDEF1-dependent manner, suggesting a possible function of seed maturation-related genes in Fe-deficient vegetative organs.