Small interfering RNAs (siRNAs) are responsible for establishing and maintaining DNA methylation through the RNA‐directed DNA methylation (RdDM) pathway in plants. Although siRNA biogenesis is well known, it is relatively unclear about how the process is regulated. By a forward genetic screen in Arabidopsis thaliana, we identified a mutant defective in NOT1 and demonstrated that NOT1 is required for transcriptional silencing at RdDM target genomic loci. We demonstrated that NOT1 is required for Pol IV‐dependent siRNA accumulation and DNA methylation at a subset of RdDM target genomic loci. Furthermore, we revealed that NOT1 is a constituent of a multi‐subunit CCR4‐NOT deadenylase complex by immunoprecipitation combined with mass spectrometry and demonstrated that the CCR4‐NOT components can function as a whole to mediate chromatin silencing. Therefore, our work establishes that the CCR4‐NOT complex regulates the biogenesis of Pol IV‐dependent siRNAs, and hence facilitates DNA methylation and transcriptional silencing in Arabidopsis.

中文翻译：

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CCR4-NOT复合物成分NOT1通过促进Pol IV依赖的siRNA产生来调节RNA定向的DNA甲基化和转录沉默。

小型干扰RNA（siRNA）负责通过植物中的RNA定向DNA甲基化（RdDM）途径建立和维持DNA甲基化。尽管siRNA的生物发生是众所周知的，但是相对如何调节该过程尚不清楚。通过拟南芥的正向遗传筛选，我们在NOT1中鉴定出一个突变缺陷基因，并证明NOT1是在RdDM目标基因组位点进行转录沉默所必需的。我们证明NOT1是依赖Rd IV靶基因组位点子集的Pol IV依赖性siRNA积累和DNA甲基化所必需的。此外，我们通过免疫沉淀结合质谱揭示了NOT1是多亚基CCR4-NOT腺苷酸酶复合物的组成部分，并表明CCR4-NOT组件可以整体上发挥功能来介导染色质沉默。因此，我们的工作建立了CCR4-NOT复合物调节依赖于Pol IV的siRNA的生物发生，从而促进了拟南芥中的DNA甲基化和转录沉默。