Uniparental expression of PolIV-dependent siRNAs in developing endosperm of Arabidopsis
Uniparental expression of PolIV-dependent siRNAs in developing endosperm of Arabidopsis
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DOI：
10.1038/nature08084
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发表时间：
2009-07-09
期刊：
影响因子：
64.8
通讯作者：
Baulcombe, David C.
中科院分区：
文献类型：
--
作者：
Mosher, Rebecca A.;Melnyk, Charles W.;Baulcombe, David C.
大多数真核生物产生基因沉默的小RNA（sRNA）介导物，其结合Argonaute蛋白并通过碱基配对将它们引导至RNA靶。通常靶向信使RNA进行降解或翻译停滞的微小RNA（miRNAs）是最好理解的sRNA类别。然而，在拟南芥花中，miRNA仅占sRNA质量的5%，序列复杂性不到0.1%。剩余的sRNA形成了由数千个基因座转录的超过100，000种不同的小干扰RNA（siRNA）的复杂群体（1-5）。拟南芥中大多数siRNA的生物发生依赖于RNA聚合酶IV（PolIV），其是DNA依赖性RNA聚合酶II的同源物2，3，6。这些PolIV依赖性（p4）-siRNA的一个子集参与应激反应，其他的与DNA或染色质的表观遗传修饰有关;然而，它们中的大多数的生物学作用尚不清楚。在这里，我们表明，p4-siRNA积累的主要阶段是在母体配子体中开始，并在种子发育过程中继续。发育中的胚乳中p4-siRNA的表达特异性地来自母本染色体。我们的研究结果为植物基因组印记和RNA沉默之间的联系提供了第一个证据。
Most eukaryotes produce small RNA (sRNA) mediators of gene silencing that bind to Argonaute proteins and guide them, by base pairing, to an RNA target. MicroRNAs (miRNAs) that normally target messenger RNAs for degradation or translational arrest are the best-understood class of sRNAs. However, in Arabidopsis thaliana flowers, miRNAs account for only 5% of the sRNA mass and less than 0.1% of the sequence complexity. The remaining sRNAs form a complex population of more than 100,000 different small interfering RNAs (siRNAs) transcribed from thousands of loci(1-5). The biogenesis of most of the siRNAs in Arabidopsis are dependent on RNA polymerase IV (PolIV), a homologue of DNA-dependent RNA polymerase II2,3,6. A subset of these PolIV-dependent (p4)-siRNAs are involved in stress responses, and others are associated with epigenetic modifications to DNA or chromatin; however, the biological role is not known for most of them. Here we show that the predominant phase of p4-siRNA accumulation is initiated in the maternal gametophyte and continues during seed development. Expression of p4-siRNAs in developing endosperm is specifically from maternal chromosomes. Our results provide the first evidence for a link between genomic imprinting and RNA silencing in plants.