Bunyaviruses cleave host cellular mRNAs to acquire cap structures for their own mRNAs in a process called cap-snatching. How bunyaviruses interact with cellular mRNA surveillance pathways such as nonsense-mediated decay (NMD) during cap-snatching remains poorly understood, especially in plants. Rice stripe virus (RSV) is a plant bunyavirus threatening rice production in East Asia. Here, with a newly developed system allowing us to present defined mRNAs to RSV in Nicotiana benthamiana, we found that the frequency of RSV to target nonsense mRNAs (nsRNAs) during cap-snatching was much lower than its frequency to target normal mRNAs. The frequency of RSV to target nsRNAs was increased by virus-induced gene silencing of UPF1 or SMG7, each encoding a protein component involved in early steps of NMD (in an rdr6 RNAi background). Coincidently, RSV accumulation was increased in the UPF1- or SMG7-silenced plants. These data indicated that the frequency of RSV to target nsRNAs during cap-snatching is restricted by NMD. By restricting the frequency of RSV to target nsRNAs, NMD may impose a constraint to the overall cap-snatching efficiency of RSV. Besides a deeper understanding for the cap-snatching of RSV, these findings point to a novel role of NMD in plant–bunyavirus interactions.

中文翻译：

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植物布尼亚病毒从无意义的 mRNA 中抢帽的频率很低，但会因 UPF1 或 SMG7 的沉默而增加

布尼亚病毒在称为帽抢夺的过程中切割宿主细胞 mRNA 以获取其自身 mRNA 的帽结构。在抢帽过程中，布尼亚病毒如何与细胞 mRNA 监测途径（如无义介导的衰变 (NMD)）相互作用仍然知之甚少，尤其是在植物中。水稻条纹病毒（RSV）是一种威胁东亚水稻生产的植物布尼亚病毒。在这里，通过一个新开发的系统，我们可以向本氏烟草中的 RSV 呈现定义的 mRNA ，我们发现在抢帽期间 RSV 靶向无义 mRNA (nsRNA) 的频率远低于其靶向正常 mRNA 的频率。病毒诱导的UPF1或SMG7基因沉默增加了 RSV 靶向 nsRNAs 的频率，每个编码参与 NMD 早期步骤的蛋白质成分（在rdr6 RNAi 背景中）。巧合的是，在UPF1或SMG7沉默的植物中 RSV 积累增加。这些数据表明，在抢帽过程中，RSV 靶向 nsRNA 的频率受到 NMD 的限制。通过将 RSV 的频率限制为目标 nsRNA，NMD 可能会对 RSV 的整体抢帽效率施加约束。除了对 RSV 的抢帽有更深入的了解外，这些发现还指出了 NMD 在植物-布尼亚病毒相互作用中的新作用。