植物DNAウイルスがクロマチンによる宿主防御を回避する仕組み(Study Reveals How Plant DNA Viruses Disarm Host’s Chromatin-Based Defenses)

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2026-10-22 中国科学院(CAS)

中国科学院華南植物園とシンガポールのテマセク生命科学研究所の研究チームは、植物DNAウイルスが宿主植物のエピジェネティックな防御機構を回避し、感染を促進する仕組みを解明した。研究では、カリフラワーモザイクウイルス(CaMV)の病原性因子P6が、シロイヌナズナの脱ユビキチン化酵素UBP12・UBP13と結合することを発見した。これらの酵素は、ウイルスゲノムを包むミニ染色体上のヒストン修飾を変化させ、ウイルス遺伝子の発現を抑制する宿主の防御機構を弱める。UBP12・UBP13の機能を失わせた植物では、ウイルスDNAや転写産物の蓄積が減少し、感染への抵抗性が高まった。また、別の植物DNAウイルスでも同様の仕組みが確認された。本成果は、植物ウイルスが宿主のエピジェネティック制御機構を利用する感染戦略を示すものであり、UBP12・UBP13を標的としたウイルス抵抗性作物の開発につながると期待される。

植物DNAウイルスがクロマチンによる宿主防御を回避する仕組み(Study Reveals How Plant DNA Viruses Disarm Host’s Chromatin-Based Defenses)
Proposed working model illustrating how CaMV P6 exploits UBP12/13 to alleviate host epigenetic silencing and promote viral infection. (Image by LI Shun)

<関連情報>

DNAウイルスの病原性因子は、シロイヌナズナの脱ユビキチン化酵素UBP12/13と相互作用してウイルス感染を促進する The pathogenicity factor of DNA virus interacts with Arabidopsis deubiquitinases UBP12/13 to promote viral infection

Shun Li,Fangqin Yu,Yi Zhang,Siqi Liu,Hui-Wen Wu,Nam-Hai Chua,Shulin Deng
Pathogens  Published: October 15, 2026
DOI:https://doi.org/10.1371/journal.ppat.1014686

Abstract

Plant DNA viruses, such as Cauliflower mosaic virus (CaMV) and Cabbage leaf curl virus (CaLCuV), are devastating pathogens that cause substantial yield losses in crops worldwide. These viruses assemble their genomes into minichromosomes with host histones. Histone post-translational modifications (PTMs) are important for viral replication and host resistance. In this study, we demonstrate that the CaMV pathogenicity factor P6 interacts with Arabidopsis deubiquitinases UBP12 and UBP13, which are typically negative regulators of plant immunity. Using affinity purification–mass spectrometry (AP-MS), we identified UBP12/13 as prominent P6 interactors and confirmed their nuclear association. CaMV infection and P6 overexpression increased UBP12 abundance, suggesting the latter promotes viral infection. By contrast, ubp12/13 mutants exhibited enhanced resistance, characterized by reduced accumulation of viral DNA and transcripts. Chromatin immunoprecipitation (ChIP)-qPCR showed that the monoubiquitinated H2A (H2Aub) and H3K27me3 modifications on the CaMV 35S promoter, but not the 19S promoter, were significantly elevated in ubp12/13 mutants compared with wild-type plants. Furthermore, UBP12/13 are also targeted by AC2, a transcriptional activator from CaLCuV, indicating a conserved strategy among plant DNA viruses. Our findings support a working model in which viral pathogenicity factors hijack UBP12/13, which in turn may alter H2Aub homeostasis on viral minichromosomes to relieve epigenetic silencing and promote infection. Together, these findings point to a previously unrecognized route by which plant DNA viruses may influence host chromatin-associated pathways and identify UBP12/13 as potential targets for engineering virus-resistant crops.

細胞遺伝子工学
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