A Genetic Network for Systemic RNA Silencing in Plants
A Genetic Network for Systemic RNA Silencing in Plants
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植物系统性 RNA 沉默的遗传网络
DOI：
10.1104/pp.17.01828
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发表时间：
2018-04-01
期刊：
影响因子：
7.4
通讯作者：
Hong, Yiguo
中科院分区：
文献类型：
--
作者：
Chen, Weiwei;Zhang, Xian;Hong, Yiguo
非细胞自主RNA沉默可以在动物和植物中从细胞传播到细胞和长距离传播。然而，植物移动的基因沉默的遗传要求和信号还知之甚少。在这里，我们确定了一个DICERLIKE 2（DCL 2）依赖的机制，转录后RNA沉默的系统传播，也称为转录后基因沉默（PTGS），在本氏烟草。利用一套与GFP报告基因偶联的转基因DCL RNAi株系，我们证明了N.本塞姆氏菌DCL 1、DCL 2、DCL 3和DCL 4分别需要产生microRNA和22、24和21 nt小干扰RNA（siRNA）。在局部初始细胞中产生的所有研究的siRNA在远端组织中以低水平存在。抑制DCL 2表达减少了基因沉默的传播，而抑制DCL 3或DCL 4表达增强了系统性PTGS。与DCL 4 RNAi系相反，DCL 2-DCL 4双RNAi系发展了与在DCL 2 RNAi中观察到的相似的系统性PTGS。我们进一步表明，由DCL 4或DCL 3产生的21或24 nt局部siRNA不参与长距离基因沉默。嫁接实验表明，DCL 2是需要在接穗响应信号，但不是在砧木产生/发送信号。这些结果表明，DCL 2在N.本塞姆氏菌，而DCL 4和DCL 3都减弱系统性PTGS。我们讨论了21，22和24 nt siRNA在系统性PTGS中的潜在作用。
Non-cell autonomous RNA silencing can spread from cell to cell and over long distances in animals and plants. However, the genetic requirements and signals involved in plant mobile gene silencing are poorly understood. Here, we identified a DICERLIKE2 (DCL2)-dependent mechanism for systemic spread of posttranscriptional RNA silencing, also known as posttranscriptional gene silencing (PTGS), in Nicotiana benthamiana. Using a suite of transgenic DCL RNAi lines coupled with a GFP reporter, we demonstrated that N. benthamiana DCL1, DCL2, DCL3, and DCL4 are required to produce microRNAs and 22, 24, and 21nt small interfering RNAs (siRNAs), respectively. All investigated siRNAs produced in local incipient cells were present at low levels in distal tissues. Inhibition of DCL2 expression reduced the spread of gene silencing, while suppression of DCL3 or DCL4 expression enhanced systemic PTGS. In contrast to DCL4 RNAi lines, DCL2-DCL4 double-RNAi lines developed systemic PTGS similar to that observed in DCL2 RNAi. We further showed that the 21 or 24 nt local siRNAs produced by DCL4 or DCL3 were not involved in long-distance gene silencing. Grafting experiments demonstrated that DCL2 was required in the scion to respond to the signal, but not in the rootstock to produce/send the signal. These results suggest a coordinated DCL genetic pathway in which DCL2 plays an essential role in systemic PTGS in N. benthamiana, while both DCL4 and DCL3 attenuate systemic PTGS. We discuss the potential role of 21, 22, and 24 nt siRNAs in systemic PTGS.