Regulation of miR399f Transcription by AtMYB2 Affects Phosphate Starvation Responses in Arabidopsis
Regulation of miR399f Transcription by AtMYB2 Affects Phosphate Starvation Responses in Arabidopsis
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DOI：
10.1104/pp.112.205922
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发表时间：
2013-01-01
期刊：
影响因子：
7.4
通讯作者：
Yun, Dae-Jin
中科院分区：
文献类型：
--
作者：
Baek, Dongwon;Kim, Min Chul;Yun, Dae-Jin
虽然已经表明microRNA399(MiR399)在植物对磷(PI)饥饿反应中的作用，但miR399基因表达的调控机制尚不清楚。在此，我们报道了AtMYB2在拟南芥PI饥饿信号中作为miR399的直接转录激活子的作用。与未转化的对照相比，高表达AtMYB2的转基因植株在高PI生长条件下表现出miR399f的表达和组织PI含量的增加，并表现出PI饥饿诱导的一组基因的高表达。与野生型相比，过量表达AtMYB2的转基因植株在PI饥饿诱导的根构型变化上更为夸张。在体外和体内，AtMYB2直接与miR399f启动子上的MYB结合，并刺激拟南芥原生质体中miR399f启动子的活性。AtMYB2的转录本身是受PI缺乏诱导的，而miR399f和AtMYB2的组织表达模式是相似的。这两个基因主要在子叶的维管组织和根中表达。我们的结果表明，AtMYB2通过调节miR399基因的表达来调节植物对PI饥饿的反应。
Although a role for microRNA399 (miR399) in plant responses to phosphate (Pi) starvation has been indicated, the regulatory mechanism underlying miR399 gene expression is not clear. Here, we report that AtMYB2 functions as a direct transcriptional activator for miR399 in Arabidopsis (Arabidopsis thaliana) Pi starvation signaling. Compared with untransformed control plants, transgenic plants constitutively overexpressing AtMYB2 showed increased miR399f expression and tissue Pi contents under high Pi growth and exhibited elevated expression of a subset of Pi starvation-induced genes. Pi starvation-induced root architectural changes were more exaggerated in AtMYB2-overexpressing transgenic plants compared with the wild type. AtMYB2 directly binds to a MYB-binding site in the miR399f promoter in vitro, as well as in vivo, and stimulates miR399f promoter activity in Arabidopsis protoplasts. Transcription of AtMYB2 itself is induced in response to Pi deficiency, and the tissue expression patterns of miR399f and AtMYB2 are similar. Both genes are expressed mainly in vascular tissues of cotyledons and in roots. Our results suggest that AtMYB2 regulates plant responses to Pi starvation by regulating the expression of the miR399 gene.