Molecular characterization of a novel hypovirus from the plant pathogenic fungus Fusarium graminearum

作者:Li, PF (Li, Pengfei)^[ 1 ] ; Zhang, HL (Zhang, Hailong)^[ 1 ] ; Chen, XG (Chen, Xiaoguang)^[ 1 ] ; Qiu, DW (Qiu, Dewen)^[ 1 ] ; Guo, LH (Guo, Lihua)^[ 1 ]

VIROLOGY

卷: 481

页: 151-160

DOI: 10.1016/j.virol.2015.02.047

出版年: JUL 2015

摘要

A novel mycovirus, termed Fusarium graminearum Hypovirus 2 (FgHV2/JS16), isolated from a plant pathogenic fungus, Fusarium graminearum strain JS16, was molecularly and biologically characterized. The genome of FgHV2/JS16 is 12,800 nucleotides (nts) long, excluding the poly (A) tail. This genome has only one large putative open reading frame, which encodes a polyprotein containing three normal functional domains, papain-like protease, RNA-dependent RNA polymerase, RNA helicase, and a novel domain with homologous bacterial SMC (structural maintenance of chromosomes) chromosome segregation proteins. A defective RNA segment that is 4553-nts long, excluding the poly (A) tail, was also detected in strain JS16. The polyprotein shared significant aa identities with Cryphonectria hypovirus 1 (CHV1) (16.8%) and CHV2 (16.2%). Phylogenetic analyses based on multiple alignments of the polyprotein clearly divided the members of Hypoviridae into two major groups, suggesting that FgHV2/JS16 was a novel hypovirus of a newly proposed genus-Alphahypovirus-composed of the members of Group 1, including CHV1, CHV2, FgHV1 and Sclerotinia sclerotiorum hypovirus 2. FgHV2/JS16 was shown to be associated with hypovirulence phenotypes according to comparisons of the biological properties shared between FgHV2/JS16-infected and FgHV2/JS16-free isogenic strains. Furthermore, we demonstrated that FgHV2/JS16 infection activated the RNA interference pathway in Fusarium graminearum by relative quantitative real time RT-PCR. (C) 2015 Elsevier Inc. All rights reserved.

关键词:dsRNA; Mycovirus; Hypoviridae; Fusarium graminearum; Fusarium head blight; FgHV2