Transcriptional Regulation of miR528 by OsSPL9 Orchestrates Antiviral Response in Rice
Transcriptional Regulation of miR528 by OsSPL9 Orchestrates Antiviral Response in Rice
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OsSPL9 对 miR528 的转录调控协调水稻的抗病毒反应
DOI：
10.1016/j.molp.2019.04.010
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发表时间：
2019-08-05
期刊：
影响因子：
27.5
通讯作者：
Li, Yi
中科院分区：
文献类型：
--
作者：
Yao, Shengze;Yang, Zhirui;Li, Yi
许多microRNA（miRNAs）是植物抗病毒防御的关键调节因子。然而，很少有人知道这些miRNAs如何在转录水平上响应病毒入侵。我们先前表明，防御水稻条纹病毒（RSV）入侵需要减少miR 528在水稻中的积累，减轻miR 528介导的L-抗坏血酸氧化酶（AO）mRNA的降解，并加强AO的抗病毒活性。在这里，我们表明miR 528-AO防御模块是由转录因子SPL 9调节的。SPL 9与miR 528启动子区的特异性基序具有高亲和力结合，并在体内激活miR 528基因的表达。SPL 9的功能丧失突变导致miR 528积累显著减少，但AO mRNA显著增加，导致植物对RSV的抗性增强。相反，转基因过表达SPL 9刺激了miR 528基因的表达，从而降低了AO mRNA的水平，损害了水稻对RSV的防御。重要的是，当SPL 9在mir 528功能丧失突变体中过表达或在表达miR 528抗性AO的转基因水稻中过表达时，不会发生RSV易感性的增加。总之，SPL 9介导的miR 528表达的转录激活的发现为miR 528-AO抗病毒防御途径增加了新的调控层。
Many microRNAs (miRNAs) are critical regulators of plant antiviral defense. However, little is known about how these miRNAs respond to virus invasion at the transcriptional level. We previously show that defense against Rice stripe virus (RSV) invasion entailed a reduction of miR528 accumulation in rice, alleviating miR528-mediated degradation of L-Ascorbate Oxidase (AO) mRNA and bolstering the antiviral activity of AO. Here we show that the miR528-AO defense module is regulated by the transcription factor SPL9. SPL9 displayed high-affinity binding to specific motifs within the promoter region of miR528 and activated the expression of miR528 gene in vivo. Loss-of-function mutations in SPL9 caused a significant reduction in miR528 accumulation but a substantial increase of AO mRNA, resulting in enhanced plant resistance to RSV. Conversely, transgenic overexpression of SPL9 stimulated the expression of miR528 gene, hence lowering the level of AO mRNA and compromising rice defense against RSV. Importantly, gain in RSV susceptibility did not occur when SPL9 was overexpressed in mir528 loss-of-function mutants, or in transgenic rice expressing a miR528-resistant AO. Taken together, the finding of SPL9-mediated transcriptional activation of miR528 expression adds a new regulatory layer to the miR528-AO antiviral defense pathway.