Repression of miR156 by miR159 Regulates the Timing of the Juvenile-to-Adult Transition in Arabidopsis
Repression of miR156 by miR159 Regulates the Timing of the Juvenile-to-Adult Transition in Arabidopsis
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DOI：
10.1105/tpc.16.00975
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发表时间：
2017-06-01
期刊：
影响因子：
11.6
通讯作者：
Wu, Gang
中科院分区：
文献类型：
--
作者：
Guo, Changkui;Xu, Yunmin;Wu, Gang
时间调节的microRNA已被确定为动物和植物发育时间的主要调节因子。在植物中，营养体发育受miR 156水平的暂时降低的调节，但是这种降低的表达如何在芽发育期间开始并随后维持仍然是难以捉摸的。在这里，我们表明，miR 159是所需的正确的时间在拟南芥的营养发展。miR 159的缺失增加了整个芽发育过程中miR 156的水平并延迟了营养发育，而miR 159的过表达略微加速了营养发育。miR 159对miR 156的抑制主要由MYB 33介导，MYB 33是miR 159靶向的R2 R3 MYB结构域转录因子。MYB 33的缺失导致了微妙的早熟营养阶段变化表型，尽管miR 156的显著下调。MYB 33通过直接结合这三个基因的启动子，同时促进MIR 156 A和MIR 156 C以及它们的靶点SPL 9的转录。我们的研究结果表明，miR 159和MYB 33不是拟南芥营养期变化的主要参与者，而是营养期变化的调节剂;即，miR 159通过抑制MYB 33的表达促进营养生长期的改变，从而防止MYB 33在整个芽发育过程中过度激活miR 156的表达，以确保拟南芥中幼龄到成体转变的正确时机。
Temporally regulated microRNAs have been identified as master regulators of developmental timing in both animals and plants. In plants, vegetative development is regulated by a temporal decrease in miR156 level, but how this decreased expression is initiated and then maintained during shoot development remains elusive. Here, we show that miR159 is required for the correct timing of vegetative development in Arabidopsis thaliana. Loss of miR159 increases miR156 level throughout shoot development and delays vegetative development, whereas overexpression of miR159 slightly accelerated vegetative development. The repression of miR156 by miR159 is predominantly mediated by MYB33, an R2R3 MYB domain transcription factor targeted by miR159. Loss of MYB33 led to subtle precocious vegetative phase change phenotypes in spite of the significant downregulation of miR156. MYB33 simultaneously promotes the transcription of MIR156A and MIR156C, as well as their target, SPL9, by directly binding to the promoters of these three genes. Rather than acting as major players in vegetative phase change in Arabidopsis, our results suggest that miR159 and MYB33 function as modifiers of vegetative phase change; i.e., miR159 facilitates vegetative phase change by repressing MYB33 expression, thus preventing MYB33 from hyperactivating miR156 expression throughout shoot development to ensure correct timing of the juvenile-to-adult transition in Arabidopsis.