Transcriptional Regulation of Arabidopsis MIR168a and ARGONAUTE1 Homeostasis in Abscisic Acid and Abiotic Stress Responses
Transcriptional Regulation of Arabidopsis MIR168a and ARGONAUTE1 Homeostasis in Abscisic Acid and Abiotic Stress Responses
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拟南芥 MIR168a 和 ARGONAUTE1 稳态在脱落酸和非生物胁迫反应中的转录调控
DOI：
10.1104/pp.111.188789
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发表时间：
2012-03-01
期刊：
影响因子：
7.4
通讯作者：
Liang, Wanqi
中科院分区：
文献类型：
--
作者：
Li, Wei;Cui, Xiao;Liang, Wanqi
脱落酸（阿坝）和非生物胁迫影响植物体内大量小RNA的积累，但其机制尚不清楚。miR 168介导的反馈调节环调节ARGONAUTE 1（AGO 1）的稳态，这对基因表达调控和植物发育至关重要。在这里，我们揭示了一个转录调控机制，MIR 168控制AGO 1在阿坝处理和非生物胁迫反应在拟南芥（拟南芥）的稳态。过表达MIR 168 a和AGO 1功能丧失突变体ago 1 -27的植株表现出阿坝敏感性和耐旱性，而mir 168 a-2突变体表现出阿坝低敏感性和干旱敏感性。在阿坝和几种非生物胁迫处理下，前体和成熟miR 168都被诱导，但在相同条件下，miR 168的靶标AGO 1没有表现出明显的下降。然而，启动子活性分析表明，AGO 1的转录活性增加阿坝和干旱处理下，这表明MIR 168 a的转录水平的提高是必要的，以维持一个稳定的AGO 1的转录水平在胁迫响应。此外，我们在体外和体内表明，MIR 168 a的转录直接调节脱落酸响应元件（ABRE）结合因子，结合到MIR 168 a启动子内的ABRE顺式元件。该ABRE基序也在多种植物物种中的MIR 168 a同源物的启动子中发现。我们的研究结果表明，miR 168的转录调控和AGO 1稳态的转录后控制可能在植物的胁迫反应和信号转导中发挥重要的和保守的作用。
The accumulation of a number of small RNAs in plants is affected by abscisic acid (ABA) and abiotic stresses, but the underlying mechanisms are poorly understood. The miR168-mediated feedback regulatory loop regulates ARGONAUTE1 (AGO1) homeostasis, which is crucial for gene expression modulation and plant development. Here, we reveal a transcriptional regulatory mechanism by which MIR168 controls AGO1 homeostasis during ABA treatment and abiotic stress responses in Arabidopsis (Arabidopsis thaliana). Plants overexpressing MIR168a and the AGO1 loss-of-function mutant ago1-27 display ABA hypersensitivity and drought tolerance, while the mir168a-2 mutant shows ABA hyposensitivity and drought hypersensitivity. Both the precursor and mature miR168 were induced under ABA and several abiotic stress treatments, but no obvious decrease for the target of miR168, AGO1, was shown under the same conditions. However, promoter activity analysis indicated that AGO1 transcription activity was increased under ABA and drought treatments, suggesting that transcriptional elevation of MIR168a is required for maintaining a stable AGO1 transcript level during the stress response. Furthermore, we showed both in vitro and in vivo that the transcription of MIR168a is directly regulated by four abscisic acid-responsive element (ABRE) binding factors, which bind to the ABRE cis-element within the MIR168a promoter. This ABRE motif is also found in the promoter of MIR168a homologs in diverse plant species. Our findings suggest that transcriptional regulation of miR168 and posttranscriptional control of AGO1 homeostasis may play an important and conserved role in stress response and signal transduction in plants.