A small peptide inhibits siRNA amplification in plants by mediating autophagic degradation of SGS3/RDR6 bodies. (22nd June 2021)

• Record Type: Journal Article
• Authors: Tong, Xin; Liu, Song‐Yu; Zou, Jing‐Ze; Zhao, Jia‐Jia; Zhu, Fei‐Fan; Chai, Long‐Xiang; Wang, Ying; Han, Chenggui; Wang, Xian‐Bing
• Is Part Of: EMBO journal. Volume 40:Number 15(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-22
• Subjects: autophagy -- peptide -- plant virus -- RNA silencing -- SGS3; Molecular biology -- Periodicals; 572.805
• DOI: 10.15252/embj.2021108050
• Languages: English
• ISSNs: 0261-4189

Abstract

Abstract: Selective autophagy mediates specific degradation of unwanted cytoplasmic components to maintain cellular homeostasis. The suppressor of gene silencing 3 (SGS3) and RNA‐dependent RNA polymerase 6 (RDR6)‐formed bodies (SGS3/RDR6 bodies) are essential for siRNA amplification in planta. However, whether autophagy receptors regulate selective turnover of SGS3/RDR6 bodies is unknown. By analyzing the transcriptomic response to virus infection in Arabidopsis, we identified a virus‐induced small peptide 1 (VISP1) composed of 71 amino acids, which harbor a ubiquitin‐interacting motif that mediates interaction with autophagy‐related protein 8. Overexpression of VISP1 induced selective autophagy and compromised antiviral immunity by inhibiting SGS3/RDR6‐dependent viral siRNA amplification, whereas visp1 mutants exhibited opposite effects. Biochemistry assays demonstrate that VISP1 interacted with SGS3 and mediated autophagic degradation of SGS3/RDR6 bodies. Further analyses revealed that overexpression of VISP1, mimicking the sgs3 mutant, impaired biogenesis of endogenous trans‐acting siRNAs and up‐regulated their targets. Collectively, we propose that VISP1 is a small peptide receptor functioning in the crosstalk between selective autophagy and RNA silencing. Synopsis: Genomic analyses have predicted numerous potentially expressed small peptides in plants, but their functions remain largely unknown. Here, a virus‐induced peptide is identified as a new autophagy receptor triggering degradation of SGS3/RDR6‐bodies and negatively regulating siRNA amplification. VISP1 is a novel virus‐induced small peptide composed of 71 amino acids in Arabidopsis . VISP1 harbors a ubiquitin‐interacting motif (UIM), which mediates the interaction with ATG8. VISP1 serves as a new autophagy receptor and triggers autophagic degradation of SGS3/RDR6‐bodies. VISP1 negatively regulates SGS3/RDR6‐dependent siRNA amplification. Abstract : VISP1, a small virus‐induced peptide, functions as an autophagy receptor to negatively regulate SGS3/RDR6‐dependent siRNA amplification in plants.