microRNA160 dictates stage-specific auxin and cytokinin sensitivities and directs soybean nodule development
microRNA160 dictates stage-specific auxin and cytokinin sensitivities and directs soybean nodule development
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DOI：
10.1111/tpj.12965
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发表时间：
2015-10-01
期刊：
影响因子：
7.2
通讯作者：
Subramanian, Senthil
中科院分区：
文献类型：
--
作者：
Nizampatnam, Narasimha Rao;Schreier, Spencer John;Subramanian, Senthil
豆科植物结瘤是植物与固氮根瘤菌相互作用的结果。植物激素细胞分裂素促进根瘤的形成，最近的研究表明植物激素生长素抑制根瘤的形成。在这里，我们表明microRNA 160（miR 160）是一个关键的信号元件，决定了生长素/细胞分裂素的平衡在大豆根瘤发育（大豆）。miR 160似乎通过抑制抑制子ARF转录因子的ARF 10/16/17家族的水平来促进生长素活性。使用定量PCR检测和荧光miRNA传感器，我们发现，miR 160水平在结节形成早期相对较低，在成熟结节中较高。我们先前已经表明，在大豆根中异位表达miR 160导致根瘤形成严重减少，加上对生长素的敏感性增强和对细胞分裂素的敏感性降低。在这里，我们表明，外源细胞分裂素恢复根瘤形成的miR 160过表达的根。因此，结节发育早期的低miR 160水平有利于结节形成所需的细胞分裂素活性。使用短串联靶模拟物（STTM 160）抑制miR 160水平导致对生长素的敏感性降低和对细胞分裂素的敏感性增强。与miR 160过表达的根相反，STTM 160根增加了结节形成，但结节成熟显著延迟。外源生长素部分恢复了STTM 160根中适当的根瘤形成和成熟，表明在根瘤发育后期高miR 160活性有利于生长素活性并促进根瘤成熟。因此，miR 160决定发育阶段特异性的敏感性生长素和细胞分裂素，以指导适当的根瘤形成和成熟的大豆。
Legume nodules result from coordinated interactions between the plant and nitrogen-fixing rhizobia. The phytohormone cytokinin promotes nodule formation, and recent findings suggest that the phytohormone auxin inhibits nodule formation. Here we show that microRNA160 (miR160) is a key signaling element that determines the auxin/cytokinin balance during nodule development in soybean (Glycine max). miR160 appears to promote auxin activity by suppressing the levels of the ARF10/16/17 family of repressor ARF transcription factors. Using quantitative PCR assays and a fluorescence miRNA sensor, we show that miR160 levels are relatively low early during nodule formation and high in mature nodules. We had previously shown that ectopic expression of miR160 in soybean roots led to a severe reduction in nodule formation, coupled with enhanced sensitivity to auxin and reduced sensitivity to cytokinin. Here we show that exogenous cytokinin restores nodule formation in miR160 over-expressing roots. Therefore, low miR160 levels early during nodule development favor cytokinin activity required for nodule formation. Suppression of miR160 levels using a short tandem target mimic (STTM160) resulted in reduced sensitivity to auxin and enhanced sensitivity to cytokinin. In contrast to miR160 over-expressing roots, STTM160 roots had increased nodule formation, but nodule maturation was significantly delayed. Exogenous auxin partially restored proper nodule formation and maturation in STTM160 roots, suggesting that high miR160 activity later during nodule development favors auxin activity and promotes nodule maturation. Therefore, miR160 dictates developmental stage-specific sensitivities to auxin and cytokinin to direct proper nodule formation and maturation in soybean.