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The AC 5 protein encoded by Mungbean yellow mosaic India virus is a pathogenicity determinant that suppresses RNA silencing‐based antiviral defenses
Author(s) -
Li Fangfang,
Xu Xiongbiao,
Huang Changjun,
Gu Zhouhang,
Cao Linge,
Hu Tao,
Ding Ming,
Li Zhenghe,
Zhou Xueping
Publication year - 2015
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.13473
Subject(s) - nicotiana benthamiana , biology , begomovirus , gene silencing , gene , potato virus x , genetics , rna silencing , rna interference , rna , transgene , ectopic expression , brome mosaic virus , dna methylation , gene expression , virology , genome , rna dependent rna polymerase
Summary 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 AC 5/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 AC 5 protein of a bipartite begomovirus, Mungbean yellow mosaic India virus ( MYMIV ). Mutational analyses and transgenic expression showed that AC 5 plays a critical role in MYMIV infection. Ectopic expression of AC 5 from a Potato virus X ( PVX ) vector resulted in severe mosaic symptoms followed by a hypersensitive‐like response in Nicotiana benthamiana . Furthermore, MYMIV AC 5 effectively suppressed post‐transcriptional gene silencing induced by single‐stranded but not double‐stranded RNA . AC 5 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 METHYLTRANSFERASE 2) in N. benthamiana . Our results demonstrate that MYMIV AC 5 is a pathogenicity determinant and a potent RNA silencing suppressor that employs novel mechanisms to suppress antiviral defenses, and suggest that the AC 5 function may be conserved among many begomoviruses.