Rice Stripe Mosaic Virus-Encoded P4 Is a Weak Suppressor of Viral RNA Silencing and Is Required for Disease Symptom Development
Rice Stripe Mosaic Virus-Encoded P4 Is a Weak Suppressor of Viral RNA Silencing and Is Required for Disease Symptom Development
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水稻条纹花叶病毒 — 编码的 P4 是病毒 RNA 沉默的弱抑制因子，是疾病症状发展所必需的
DOI：
10.1094/mpmi-08-19-0239-ia
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发表时间：
2020-03-01
影响因子：
3.5
通讯作者：
Wu, Jianguo
中科院分区：
文献类型：
--
作者：
Zhang, Chao;Chen, Dong;Wu, Jianguo
病毒RNA沉默抑制子（VSRs）是一组病毒蛋白，其已经进化以抵消真核抗病毒RNA沉默途径，从而有助于病毒致病性。本研究揭示了水稻条纹花叶病毒（RSMV）编码的基质蛋白P4是一种弱RNA沉默抑制因子。通过酵母双杂交、双分子荧光互补和亚细胞共定位等实验，证明P4与水稻内源基因沉默抑制子3（OsSGS3）相互作用。我们还确定P4过表达对OsSGS3转录没有影响。而P4可通过泛素化和自噬促进OsSGS3的降解。此外，使用基于马铃薯病毒X的表达系统来证实P4通过促进过氧化氢积累而不是细胞死亡来增强本氏烟草叶片上的花叶症状的发展。为了验证P4是否是宿主植物中的致病因子，我们产生了转基因P4过表达的水稻植株，其表现出与疾病相关的发育缺陷，包括株高降低和分蘖过多。我们的数据表明，RSMV编码的P4作为一个弱VSR，通过靶向OsSGS3抑制抗病毒RNA沉默。
Viral suppressors of RNA silencing (VSRs) are a cluster of viral proteins that have evolved to counteract eukaryotic antiviral RNA silencing pathways, thereby contributing to viral pathogenicity. In this study, we revealed that the matrix protein P4 encoded by rice stripe mosaic virus (RSMV), which is an emerging cytoplasmic rhabdovirus, is a weak RNA silencing suppressor. By conducting yeast two-hybrid, bimolecular fluorescence complementation, and subcellular colocalization assays, we proved that P4 interacts with the rice endogenous suppressor of gene silencing 3 (OsSGS3). We also determined that P4 overexpression has no effect on OsSGS3 transcription. However, P4 can promote the degradation of OsSGS3 via ubiquitination and autophagy. Additionally, a potato virus X-based expression system was used to confirm that P4 enhances the development of mosaic symptoms on Nicotiana benthamiana leaves by promoting hydrogen peroxide accumulation but not cell death. To verify whether P4 is a pathogenicity factor in host plants, we generated transgenic P4-overexpressing rice plants that exhibited disease-related developmental defects including decreased plant height and excessive tillering. Our data suggest that RSMV-encoded P4 serves as a weak VSR that inhibits antiviral RNA silencing by targeting OsSGS3.