Introduction of transgene DNA may lead to specific degradation of RNAs that are homologous to the transgene transcribed sequence through phenomena named post-transcriptional gene silencing (PTGS) in plants, quelling in fungi, and RNA interference (RNAi) in animals. It was shown previously that PTGS, quelling, and RNAi require a set of related proteins (SGS2, QDE-1, and EGO-1, respectively). Here we report the isolation of Arabidopsis mutants impaired in PTGS which are affected at the Argonaute1 (AGO1) locus. AGO1 is similar to QDE-2 required for quelling and RDE-1 required for RNAi. Sequencing of ago1 mutants revealed one amino acid essential for PTGS that is also present in QDE-2 and RDE-1 in a highly conserved motif. Taken together, these results confirm the hypothesis that these processes derive from a common ancestral mechanism that controls expression of invading nucleic acid molecules at the post-transcriptional level. As opposed to rde-1 and qde-2 mutants, which are viable, ago1 mutants display several developmental abnormalities, including sterility. These results raise the possibility that PTGS, or at least some of its elements, could participate in the regulation of gene expression during development in plants.

中文翻译：

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AGO1、QDE-2 和 RDE-1 是植物转录后基因沉默、真菌抑制和动物 RNA 干扰所需的相关蛋白。


转基因DNA的引入可能会通过植物中的转录后基因沉默（PTGS）、真菌中的抑制和动物中的RNA干扰（RNAi）现象导致与转基因转录序列同源的RNA的特异性降解。之前的研究表明，PTGS、抑制和 RNAi 需要一组相关蛋白（分别为 SGS2、QDE-1 和 EGO-1）。在这里，我们报告了 PTGS 受损的拟南芥突变体的分离，这些突变体在 Argonaute1 (AGO1) 位点受到影响。 AGO1 类似于抑制所需的 QDE-2 和 RNAi 所需的 RDE-1。 ago1 突变体的测序揭示了 PTGS 必需的一个氨基酸，该氨基酸也以高度保守的基序存在于 QDE-2 和 RDE-1 中。总而言之，这些结果证实了以下假设：这些过程源自共同的祖先机制，该机制在转录后水平控制入侵核酸分子的表达。与可存活的 rde-1 和 qde-2 突变体相反，ago1 突变体表现出多种发育异常，包括不育。这些结果提出了 PTGS 或至少其某些元件可能参与植物发育过程中基因表达调控的可能性。