Flowering plants and mammals contain imprinted genes that are primarily expressed in the endosperm and placenta in a parent-of-origin manner. In this study, we show that early activation of the geminivirus genes C2 and C3 in Arabidopsis (Arabidopsis thaliana) plants, encoding a viral suppressor of RNA interference and a replication enhancer protein, respectively, is correlated with the transient vegetative expression of VARIANT IN METHYLATION5 (VIM5), an endosperm imprinted gene that is conserved in diverse plant species. VIM5 is a ubiquitin E3 ligase that directly targets the DNA methyltransferases MET1 and CMT3 for degradation by the ubiquitin-26S proteasome proteolytic pathway. Infection with Beet severe curly top virus induced VIM5 expression in rosette leaf tissues, possibly via the expression of the viral replication initiator protein, leading to the early activation of C2 and C3 coupled with reduced symmetric methylation in the C2-3 promoter and the onset of disease symptoms. These findings demonstrate how this small DNA virus recruits a host imprinted gene for the epigenetic activation of viral gene transcription. Our findings reveal a distinct strategy used by plant pathogens to exploit the host machinery in order to inhibit methylation-mediated defense responses when establishing infection.

开花植物和哺乳动物含有印记基因，这些基因主要以亲本方式在胚乳和胎盘中表达。在这项研究中，我们发现拟南芥（Arabidopsis thaliana）植物中双生病毒基因C2和C3的早期激活（分别编码RNA干扰的病毒抑制子和复制增强子蛋白）与VARIANT IN METHYLATION5的瞬时营养表达相关。 ( VIM5 )，一种在多种植物物种中保守的胚乳印记基因。VIM5 是一种泛素 E3 连接酶，直接靶向 DNA 甲基转移酶 MET1 和 CMT3，通过泛素-26S 蛋白酶体蛋白水解途径进行降解。感染甜菜严重卷顶病毒在莲座叶组织中诱导VIM5表达，可能是通过病毒复制起始蛋白的表达，导致C2和C3的早期激活，以及C2-3启动子中对称甲基化的减少和疾病症状的出现。这些发现证明了这种小型 DNA 病毒如何招募宿主印记基因来进行病毒基因转录的表观遗传激活。我们的研究结果揭示了植物病原体在建立感染时利用宿主机制来抑制甲基化介导的防御反应的独特策略。