Viral-inducible Argonaute18 confers broad-spectrum virus resistance in rice by sequestering a host microRNA.
Viral-inducible Argonaute18 confers broad-spectrum virus resistance in rice by sequestering a host microRNA.
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作者：
Wu J;Yang Z;Wang Y;Zheng L;Ye R;Ji Y;Zhao S;Ji S;Liu R;Xu L;Zheng H;Zhou Y;Zhang X;Cao X;Xie L;Wu Z;Qi Y;Li Y
病毒病原体是全世界水稻生产的主要威胁。虽然已知RNA干扰（RNAi）在植物和动物模型中介导抗病毒免疫，但对水稻和其他重要经济作物中的抗病毒RNAi机制知之甚少。在这里，我们报告说，水稻对进化上不同的病毒的抗性需要Argonaute18（AGO18）。遗传学研究表明，AGO18的抗病毒功能取决于其螯合microRNA168（miR168）的活性，以减轻对抗病毒RNAi所必需的水稻AGO1的抑制。在ago18背景中表达miR168抗性AGO1a拯救或增加水稻抗病毒活性值得注意的是，AGO18的稳定转基因表达赋予水稻广谱病毒抗性。我们的研究结果揭示了一种新的合作抗病毒活性的两个不同的AGO蛋白，并提出了一个新的战略，为控制水稻病毒病。DOI：www.example.com水稻是一种主要的粮食作物，提供了全世界人们消耗的五分之一以上的卡路里。因此，重要的是找到预防影响水稻植物的疾病的方法。许多感染水稻的病毒是通过昆虫在植物之间传播的，许多昆虫一次携带一种以上的病毒;这意味着很难预测疾病下一次会在哪里出现。因此，迫切需要开发新的有效策略，提高水稻植物抵抗有害病毒的能力。植物防御病毒的一种方法是使用一种称为RNA干扰的系统来识别和破坏病毒产生的RNA分子。这个过程依赖于Argonaute（AGO）蛋白质家族，尽管其许多成员的作用还不清楚。其中一种研究得比较好的AGO蛋白被称为AGO1，已知它对保护植物免受病毒侵害很重要。不幸的是，一种名为miR168的小RNA分子可以限制细胞中AGO1的数量，并且miR168的水平在病毒感染的水稻植物中增加。Wu，Yang等人将水稻植物暴露于两种昆虫，每种昆虫携带不同的植物病毒。感染这些病毒的水稻植株增加了AGO 1和另一种称为AGO 18的AGO蛋白的水平。改变水稻植物产生AGO18的能力揭示了AGO1的抗病毒活性在缺乏AGO18的植物中被消除。然而，过量生产AGO18的植物能够更好地抵御病毒感染。Wu，Yang等人进一步表明AGO18与miR168结合，从而阻止这种小RNA降低AGO1水平。因此，AGO 1和AGO 18共同作用以保护水稻免受病毒的侵害。吴，杨等人认为，工程水稻植物产生更多的AGO 18可以使它们对病毒更具抵抗力。还需要进一步的工作来确认AGO1和AGO18是否也一起工作来防御水稻免受迄今为止测试的两种病毒以外的病毒的侵害，并调查这些蛋白质是否在其他作物中也发挥类似的作用。DOI：www.example.com网站
Viral pathogens are a major threat to rice production worldwide. Although RNA interference (RNAi) is known to mediate antiviral immunity in plant and animal models, the mechanism of antiviral RNAi in rice and other economically important crops is poorly understood. Here, we report that rice resistance to evolutionarily diverse viruses requires Argonaute18 (AGO18). Genetic studies reveal that the antiviral function of AGO18 depends on its activity to sequester microRNA168 (miR168) to alleviate repression of rice AGO1 essential for antiviral RNAi. Expression of miR168-resistant AGO1a in ago18 background rescues or increases rice antiviral activity. Notably, stable transgenic expression of AGO18 confers broad-spectrum virus resistance in rice. Our findings uncover a novel cooperative antiviral activity of two distinct AGO proteins and suggest a new strategy for the control of viral diseases in rice. DOI: http://dx.doi.org/10.7554/eLife.05733.001 Rice is a major food crop, providing over a fifth of all calories consumed by people around the world. As such, it is important to find ways to prevent the diseases that affect rice plants. Many of the viruses that infect rice are transferred between plants by insects and many insects carry more than one virus at a time; this means it can be difficult to predict where a disease will next emerge. As a result, there is a pressing need to develop new and effective strategies that boost the ability of rice plants to fight off harmful viruses. One way that plants defend themselves from viruses involves using a system called RNA interference to identify and destroy the RNA molecules that viruses produce. This process depends on the Argonaute (AGO) family of proteins, although the roles of many of its members are not well understood. One of the better-studied AGO proteins is called AGO1 and is known to be important for defending plants against viruses. Unfortunately, a small RNA molecule called miR168 acts to limit the amount of AGO1 in a cell, and the levels of miR168 increase in virus-infected rice plants. Wu, Yang et al. exposed rice plants to two species of insect that each carried a different plant virus. Rice plants infected with these viruses increased their levels of both AGO1 and another AGO protein called AGO18. Modifying the ability of rice plants to produce AGO18 revealed that the anti-viral activity of AGO1 is abolished in plants lacking AGO18. However, plants that over-produce AGO18 are better able to fight off viral infections. Wu, Yang et al. further showed that AGO18 binds to miR168 and so prevents this small RNA from reducing AGO1 levels. Therefore, AGO1 and AGO18 work together to defend rice plants from viruses. Wu, Yang et al. suggest that engineering rice plants to make more AGO18 could make them more resistant to viruses. Further work will be needed to confirm whether AGO1 and AGO18 also work together to defend rice against viruses other than the two tested so far and to investigate whether these proteins also perform similar roles in other crops. DOI: http://dx.doi.org/10.7554/eLife.05733.002