Zhao Liling, Chen Yingfang, Xiao Xingming, Gao Haiying, Cao Jiamin, Zhang Zhongkai, Guo Zhongxin
Vector-borne Virus Research Center, State Key Laboratory for Ecological Pest Control of Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002 China.
Key Laboratory of Agricultural Biotechnology of Yunnan Province, Biotechnology and Germplasm Resources Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, 650221 China.
Hortic Res. 2023 Mar 13;10(5):uhad043. doi: 10.1093/hr/uhad043. eCollection 2023 May.
Evolutionarily conserved antiviral RNA interference (RNAi) mediates a primary antiviral innate immunity preventing infection of broad-spectrum viruses in plants. However, the detailed mechanism in plants is still largely unknown, especially in important agricultural crops, including tomato. Varieties of pathogenic viruses evolve to possess viral suppressors of RNA silencing (VSRs) to suppress antiviral RNAi in the host. Due to the prevalence of VSRs, it is still unknown whether antiviral RNAi truly functions to prevent invasion by natural wild-type viruses in plants and animals. In this research, for the first time we applied CRISPR-Cas9 to generate , , or mutants for two differentiated AGO2s, key effectors in antiviral RNAi. We found that AGO2a but not AGO2b was significantly induced to inhibit the propagation of not only VSR-deficient Cucumber mosaic virus (CMV) but also wild-type CMV-Fny in tomato; however, neither AGO2a nor AGO2b regulated disease induction after infection with either virus. Our findings firstly reveal a prominent role of AGO2a in antiviral RNAi innate immunity in tomato and demonstrate that antiviral RNAi evolves to defend against infection of natural wild-type CMV-Fny in tomato. However, AGO2a-mediated antiviral RNAi does not play major roles in promoting tolerance of tomato plants to CMV infection for maintaining health.
进化上保守的抗病毒RNA干扰（RNAi）介导了一种主要的抗病毒先天免疫，可防止植物受到广谱病毒的感染。然而，植物中的详细机制在很大程度上仍然未知，尤其是在包括番茄在内的重要农作物中。多种致病病毒进化出具有RNA沉默病毒抑制子（VSR），以抑制宿主中的抗病毒RNAi。由于VSR的普遍存在，抗病毒RNAi是否真的在植物和动物中发挥作用以防止天然野生型病毒的入侵仍不清楚。在本研究中，我们首次应用CRISPR-Cas9技术针对抗病毒RNAi中的关键效应因子——两个分化的AGO2基因产生AGO2a、AGO2b或AGO2a/AGO2b双突变体。我们发现，AGO2a而非AGO2b在番茄中被显著诱导，不仅能抑制缺乏VSR的黄瓜花叶病毒（CMV）的传播，还能抑制野生型CMV-Fny的传播；然而，AGO2a和AGO2b均未调节感染这两种病毒后的疾病诱导。我们的研究结果首次揭示了AGO2a在番茄抗病毒RNAi先天免疫中的突出作用，并证明抗病毒RNAi进化以抵御番茄中天然野生型CMV-Fny的感染。然而，AGO2a介导的抗病毒RNAi在促进番茄植株对CMV感染的耐受性以维持健康方面并不起主要作用。
