ABA induction of miR159 controls transcript levels of two MYB factors during Arabidopsis seed germination
ABA induction of miR159 controls transcript levels of two MYB factors during Arabidopsis seed germination
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DOI：
10.1111/j.1365-313x.2006.02980.x
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发表时间：
2007-02-01
期刊：
影响因子：
7.2
通讯作者：
Chua, Nam-Hai
中科院分区：
文献类型：
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作者：
Reyes, Jose L.;Chua, Nam-Hai
种子吸胀后，脱落酸（阿坝）水平下降，使胚发芽并发育成幼苗。然而，在非生物胁迫条件下，阿坝水平仍然很高，生长和发育受到抑制。已知几种转录因子，包括脱落酸不敏感（ABI）3和ABI 5，控制这种发育检查点。在这里，我们表明，在萌发的拟南芥种子，阿坝诱导积累的microRNA 159（miR 159）在ABI 3依赖的方式，和miRNA 159介导的切割MYB 101和MYB 33转录在体外和体内。这两个MYB转录因子的功能作为阿坝反应的正调节剂，myb 33和myb 101的无效突变体显示对激素的低敏感性。与此一致，miR 159过表达抑制MYB 33和MYB 101转录水平并使植物对阿坝低敏感，而过表达MYB 33和MYB 101的抗切割形式的转基因植物是过敏的，正如过表达芜菁花叶病毒（TuMV）P1/HC-Pro病毒蛋白的植物一样，已知该病毒蛋白抑制miRNA功能。我们的研究结果表明，ABA诱导的miR 159的积累是一种稳态机制，指导MYB 33和MYB 101转录降解，以脱敏激素信号在幼苗胁迫反应。
Upon seed imbibition, abscisic acid (ABA) levels decrease to allow embryos to germinate and develop into seedlings. However, under abiotic stress conditions, ABA levels remain high, and growth and development are arrested. Several transcription factors, including abscisic acid-insensitive (ABI)3 and ABI5, are known to control this developmental checkpoint. Here, we show that, in germinating Arabidopsis thaliana seeds, ABA induces the accumulation of microRNA 159 (miR159) in an ABI3-dependent fashion, and miRNA159 mediates cleavage of MYB101 and MYB33 transcripts in vitro and in vivo. The two MYB transcription factors function as positive regulators of ABA responses, as null mutants of myb33 and myb101 show hyposensitivity to the hormone. Consistent with this, miR159 over-expression suppresses MYB33 and MYB101 transcript levels and renders plants hyposensitive to ABA, whereas transgenic plants over-expressing cleavage-resistant forms of MYB33 and MYB101 are hypersensitive, as are plants over-expressing the Turnip mosaic virus (TuMV) P1/HC-Pro viral protein that is known to inhibit miRNA function. Our results suggest that ABA-induced accumulation of miR159 is a homeostatic mechanism to direct MYB33 and MYB101 transcript degradation to desensitize hormone signaling during seedling stress responses.