Areca palm velarivirus 1 encoded CP suppresses antiviral RNA silencing - mediating the autophagic degradation of SGS3 and disrupting the SGS3–RDR6 interaction

Sep 29, 2026

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Areca palm velarivirus 1 (APV1) drives yellow leaf disease, causing major yield losses in areca palms, yet its counteraction of host immunity has been poorly defined. RNA silencing is a conserved eukaryotic antiviral defense, and this work identifies the APV1 capsid protein (CP) as a viral suppressor of RNA silencing (VSR). CP inhibits local and systemic ssRNA-triggered silencing by binding Suppressor of Gene Silencing 3 (SGS3/AcSGS3), promoting its autophagic degradation, and disrupting the SGS3–RDR6 interaction, thereby impairing RNAi signaling.

LanguageEnglish

CategoryResearch & Report

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Pages10

Reading Time25 min

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Introduction

RNA silencing as conserved antiviral defense

Viral suppressors targeting SGS3–RDR6 and related factors

Autophagy in antiviral defense

Wen et al. Stress Biology (2026) 6:1 [https://doi.org/10.1007/s44154-025-00279-w](https://doi.org/10.1007/s44154-025-00279-w) Stress Biology ORIGINAL PAPER Open Access Areca palm velarivirus 1 encoded CP suppresses antiviral RNA silencing by mediating the autophagic degradation of SGS3 and disrupting the SGS3–RDR6 interaction Jiawei Wen1†, Huili Li1†, Zemu Li1, Hongxing Wang1, Xianmei Cao1* and Xi Huang1* Abstract Areca palm velarivirus 1 (APV1) is the causative agent of yellow leaf disease (YLD), leading to severe yield losses in areca palms. However, how APV1 counteracts host immunity remains largely underexplored, and the underlying mechanisms are still poorly understood. RNA silencing is an evolutionarily conserved antiviral defense mechanism in eukaryotes. In this study, we identify the APV1-encoded capsid protein (CP) as a viral suppressor of RNA silencing (VSR) that inhibits both local and systemic silencing triggered by single-stranded RNA (ssRNA) . Mechanistically, CP interacts with host Suppressor of Gene Silencing 3 (AcSGS3), a key component of the RNA silencing pathway, and promotes its degradation via autophagy. Additionally, CP disrupts the SGS3–AcRDR6 (RNA-dependent RNA polymerase 6) interaction, impairing the RNAi signaling cascade. Our findings reveal a novel dual mechanism to counteract host RNA silencing in which APV1 CP disrupts the SGS3–AcRDR6 complex and exploits the autophagic pathway to degrade AcSGS3, thereby undermining host antiviral defenses. Keywords Areca palm velarivirus 1, Autophagy, CP, SGS3, RDR6 Introduction RNA silencing is an evolutionarily conserved mechanism of sequence-specific gene regulation that plays essential roles in growth, development, genome integrity, and stress adaptation in eukaryotes (Zhao and Guo 2022). The pathway is typically initiated by double-stranded RNA (dsRNA), or hairpin-structured RNA, or microRNA, which is cleaved into 21–24 nucleotide small | Handling Editor: Rosa Lozano-Duran. | | --- | | †Jiawei Wen and Huili Li contributed equally to this work. | *Correspondence: Xianmei Cao [184419@hainanu.edu.cn](184419@hainanu.edu.cn)[ ](184419@hainanu.edu.cn)Xi Huang [xihuang@hainanu.edu.cn](xihuang@hainanu.edu.cn) 1 National Key Laboratory for Tropical Crop Breeding, School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya Hainan 572025, China interfering RNAs (siRNAs) by RNase III enzymes such as DICER in animals and DICER-LIKE proteins (DCL) in plants (Lopez-Gomollon and Baulcombe 2022; Csorba et al. 2015). These siRNAs are then loaded into ARGONAUTE (AGO) proteins to form the RNA-induced silencing complex (RISC), which guides the sequencespecific degradation or translational repression of complementary target transcripts. Viral RNAs are often targeted because they form double-stranded RNA intermediates during replication or contain extensive secondary structures that trigger the production of viral-derived siRNAs. RNA silencing is thus a conserved immune weapon triggered by the infecting virus. To amplify the silencing signal, host RNA-dependent RNA polymerases (RDRs) synthesize secondary dsRNAs, leading to the production of additional siRNAs. In plants, the Suppressor of Gene Silencing 3 (SGS3) interacts with RDR6 to form the SGS3/RDR6 complex, a crucial module that © The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence

FAQs

What is the main role of APV1 capsid protein (CP) in antiviral RNA silencing?

APV1-encoded CP functions as a viral suppressor of RNA silencing by blocking both local and systemic RNA silencing triggered by ssRNA.

How does CP affect the host SGS3 protein?

CP interacts with host Suppressor of Gene Silencing 3 (AcSGS3) and promotes its degradation via the autophagy pathway.

How does CP interfere with RNAi signaling beyond SGS3 degradation?

CP disrupts the SGS3–AcRDR6 interaction, impairing the RNAi signaling cascade.

Sep 29, 2026

Upload by Oliver