N-terminal domain of Rep encoded by beet severe curly top virus mediates suppression of RNA silencing and induces <i>VIM5</i> expression.

Jingyu XU; Jianxin LU; Zhenyu YU; Meijie HU; Chengkai GUO; Zhongqi QIU; Zhongqi CHEN

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N-terminal domain of Rep encoded by beet severe curly top virus mediates suppression of RNA silencing and induces VIM5 expression.

Author: Jingyu XU ¹ ; Jianxin LU ² ; Zhenyu YU ³ ; Meijie HU ² ; Chengkai GUO ² ; Zhongqi QIU ² ; Zhongqi CHEN ²
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1. State Key Laboratory of Agricultural and Forestry Biosecurity, School of Future Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China.
2. State Key Laboratory of Agricultural and Forestry Biosecurity, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China.
3. State Key Laboratory of Agricultural and Forestry Biosecurity, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China.
Publication Type:Journal Article
Keywords: beet severe curly top virus (BSCTV); geminviruses; replication initiator protein (Rep); viral suppressor of RNA silencing (VSR)
MeSH: Geminiviridae/genetics*; Nicotiana/metabolism*; Arabidopsis/metabolism*; RNA Interference; Viral Proteins/metabolism*; Arabidopsis Proteins/metabolism*; Plants, Genetically Modified/metabolism*; Protein Domains; Plant Diseases/virology*; Methyltransferases/metabolism*; Ubiquitin-Protein Ligases/metabolism*; DNA Helicases/genetics*
From: Chinese Journal of Biotechnology 2025;41(10):3956-3968
CountryChina
Language:Chinese
Abstract: Geminiviruses cause substantial crop yield losses worldwide. The replication initiator protein (Rep) encoded by geminiviruses is indispensable for geminiviral replication. The Rep protein encoded by beet severe curly top virus (BSCTV, genus Curtovirus, family Geminiviridae) induces VARIANT IN METHYLATION 5 (VIM5) expression in Arabidopsis leaves upon BSCTV infection. VIM5 functions as a ubiquitination-related E3 ligase to promote the proteasomal degradation of methyltransferases, resulting in reduction of methylation levels in the BSCTV C2-3 promoter. However, the specific domains of Rep responsible for VIM5 induction remain poorly characterized. Although Rep proteins from several geminiviruses act as viral suppressors of RNA silencing (VSRs), whether BSCTV Rep also possesses VSR activity remains to be illustrated. In this study, we employed a transient expression system in the 16c-GFP transgenic and the wild-type Nicotiana benthamiana plants to analyze the VSR and the VIM5-inducing activities of different truncated Rep proteins haboring distinct domains. We found that the N-terminal domain (amino acids 1-180) of Rep suppressed GFP silencing in 16c-GFP transgenic N. benthamiana leaves. The minimal N-terminal fragment (amino acids 1-104) induced VIM5 expression upon co-infiltration, while C-terminal truncations lacked VIM5-inducing activity. Our results indicate that the N-terminal domain of Rep encoded by BSCTV mediates the suppression of RNA silencing and induces VIM5 expression. Thus, our findings contribute to a better understanding of interactions between geminiviral Rep and plant hosts.