title: The AC5 protein encoded by Mungbean yellow mosaic India virus is a pathogenicity determinant that suppresses RNA silencing-based antiviral defenses.
abstract: It is generally accepted that begomoviruses in the family Geminiviridae encode four proteins (from AC1/C1 to AC4/C4) using the complementary-sense DNA as template. Although AC5/C5 coding sequences are increasingly annotated in databases for many begomoviruses, the evolutionary relationships and functions of this putative protein in viral infection are obscure. Here, we demonstrate several important functions of the AC5 protein of a bipartite begomovirus, Mungbean yellow mosaic India virus (MYMIV). Mutational analyses and transgenic expression showed that AC5 plays a critical role in MYMIV infection. Ectopic expression of AC5 from a Potato virus X (PVX) vector resulted in severe mosaic symptoms followed by a hypersensitive-like response in Nicotiana benthamiana. Furthermore, MYMIV AC5 effectively suppressed post-transcriptional gene silencing induced by single-stranded but not double-stranded RNA. AC5 was also able to reverse transcriptional gene silencing of a green fluorescent protein transgene by reducing methylation of promoter sequences, probably through repressing expression of a CHH cytosine methyltransferase (DOMAINS REARRANGED METHYLTRANSFERASE2) in N. benthamiana. Our results demonstrate that MYMIV AC5 is a pathogenicity determinant and a potent RNA silencing suppressor that employs novel mechanisms to suppress antiviral defenses, and suggest that the AC5 function may be conserved among many begomoviruses.
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.|State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
authors.forename: Fangfang
authors.initials: F
authors.lastname: Li
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Xiongbiao
authors.initials: X
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Changjun
authors.initials: C
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Zhouhang
authors.initials: Z
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Linge
authors.initials: L
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Hu
authors.affiliation: Institute of Plant Protection, Yunnan Provincial Academy of Agricultural Sciences, Kunming, Yunnan, 650205, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Zhenghe
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key Laboratory of Rice Biology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.|State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
authors.forename: Xueping
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000998:Antiviral Agents / Q000378:metabolism*; D053839:Begomovirus / Q000378:metabolism* / Q000472:pathogenicity*; D019175:DNA Methylation; D007887:Fabaceae / Q000276:immunology / Q000821:virology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000821:virology; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D014026:Nicotiana / Q000235:genetics / Q000821:virology; D014158:Transcription, Genetic; D019076:Transgenes; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D000998:Antiviral Agents; D014764:Viral Proteins; D049452:Green Fluorescent Proteins
keywords: AC5; DOMAINS REARRANGED METHYLTRANSFERASE2; Mungbean yellow mosaic India virus; geminivirus; post-transcriptional gene silencing (PTGS); suppressor of RNA silencing; transcriptional gene silencing (TGS)