Molecular and Genomic Characterization of Novel Polymycovirus from Fusarium spp.

Abstract

Mycoviruses are widely distributed and infect a diverse range of fungal hosts across the globe. The current study reports the molecular and genomic characterization of a novel double stranded RNA virus named Fusarium oxysporum polymycovirus 1 (FoPmV1), This novel virus was found to infect a Pakistani isolate (P2A) of the phytopathogenic fungus Fusarium oxysporum through screening of infected soil samples. The Next-generation sequencing technology revealed the presence of polymycovirus, classifying it as a distinct member of the genus Polymycovirus. FoPmV1consists of six segments, dsRNA1 (2367 bp), dsRNA2 (2433 bp), dsRNA3 (2054 bp), dsRNA4 (1353 bp), dsRNA5 (1242 bp) and dsRNA6 (1051 bp). The dsRNA1-encoded protein harbors an RNA-dependent RNA polymerase domain and exhibits 76.52% sequence identity with the corresponding protein of Fusarium redolens polymycovirus 1 (FrPmV1), while showing lower levels of amino acid similarity with putative polymycoviruses and fungal dsRNA viruses from diverse families. Similarly, the proteins encoded by dsRNA2 to dsRNA4 showed sequence similarity to the cognate proteins found in FrPmV1. However, dsRNA5 and 6 encoded proteins were found to be unique showing no sequence homology to the reported viruses. Internal confirmation of NGS contigs via reverse transcriptase polymerase chain reaction validated the presence of the viral genome within the fungal host. Polymycoviruses are a relatively newly discovered group and are designated as dsRNA viruses, whilst the phylogenetic analyses of these structural proteins demonstrated an evolutionary link between single-stranded RNA viruses and double-stranded RNA viruses. To the best of our knowledge, this is the first report of polymycovirus infecting Fusarium oxysporum.