中文摘要：从病毒特有dsRNA加工而来的小干扰RNAs (siRNAs)引导着不同真核宿主中的抗病毒RNA干扰(RNAi)。作者最近在拟南芥中进行了致敏遗传筛选，并确定了两个相关的磷脂翻转酶（磷脂翻转酶是抗病毒RNAi以及病毒衍生的siRNAs通过植物RNA依赖性RNA聚合酶1（RDR1）和RDR6进行扩增所需要的）。本研究报道了来自同样的遗传筛选的抗病毒RNAI-缺陷2 (AVI2)的鉴定和克隆。研究发现了AVI2和AVI1翻转酶之间特定的遗传相互作用，这是植物发育的关键。作者认为，AVI1和AVI2参与了病毒诱导的RDR1/RDR6特异性膜结合RNA合成（对于高度丰富的病毒siRNAs和vasi-RNAs的生物起源是必不可少的）的形成。
外文摘要：Small interfering RNAs (siRNAs) processed from virus-specific dsRNA direct antiviral RNA interference (RNAi) in diverse eukaryotic hosts. We have recently performed a sensitized genetic screen in Arabidopsis thaliana and identified two related phospholipid flippases required for antiviral RNAi and the amplification of virus-derived siRNAs by plant RNA-dependent RNA polymerase 1 (RDR1) and RDR6. Here we report the identification and cloning of ANTIVIRAL RNAI-DEFECTIVE 2 (AVI2) from the same genetic screen. AVI2 encodes a multi-span transmembrane protein broadly conserved in plants and animals with two homologous human proteins known as magnesium transporters. We show that avi2 mutant plants display no developmental defects and develop severe disease symptoms after infection with a mutant Cucumber mosaic virus (CMV) defective in RNAi suppression. AVI2 is induced by CMV infection, particularly in veins, and is required for antiviral RNAi and RDR6-dependent biogenesis of viral siRNAs. AVI2 is also necessary for Dicer-like 2 (DCL2)-mediated amplification of 22-nucleotide viral siRNAs induced in dcl4 mutant plants by infection, but dispensable for RDR6-dependent biogenesis of endogenous trans-acting siRNAs. Further genetic studies illustrate that AVI2 plays a partially redundant role with AVI2H, the most closely related member in the AVI2 gene family, in RDR1-dependent biogenesis of viral siRNAs and the endogenous virus-activated siRNAs (vasi-RNAs). Interestingly, we discovered a specific genetic interaction of AVI2 with AVI1 flippase that is critical for plant development. We propose that AVI1 and AVI2 participate in the virus-induced formation of RDR1/RDR6-specific, membrane-bound RNA synthesis compartment essential for the biogenesis of highly abundant viral siRNAs and vasi-RNAs.
作者：Guo, Zhongxin; Wang, Xian-Bing; Wang, Ying; 等
作者单位：加州大学河滨分校
期刊名称：Plant Physiology
期刊影响因子：6.456
出版年份：2018
出版刊次：2
点击下载：抗病毒RNAi的新宿主因子的鉴定及病毒性siRNAs的扩增研究