Identification and complete genome sequencing of a novel betapartitivirus naturally infecting the mycorrhizal desert truffle Terfezia claveryi

Abstract

Viruses that naturally infect fungal species and capable of establishing mycorrhizae are largely unknown. In this study, we identified and characterized a new partitivirus inhabiting the ascomycete, mycorrhizal desert truffle species Terfezia claveryi, and named it "Terfezia claveryi partitivirus 1" (TcPV1). The entire genome of TcPV1, sequenced by both high throughput sequencing of the total dsRNA extracts and by Sanger sequencing of the RLM-RACE PCR products comprised two dsRNA segments of 2404 bp and 2374 bp, respectively. Both dsRNA genome segments harbored a single open reading frame (ORF), encoding a putative RNA-dependent RNA polymerase (RdRp), and a capsid protein (CP), respectively. The BLASTp search of the RdRp and CP sequences revealed the highest sequence identities (41.92% and 24.13% identity, respectively) to those of Bipolaris maydis partitivirus 2 and Plasmopara viticola lesion associated partitivirus 5. Molecular phylogenetic analyses of the RdRp sequence showed that TcPV1 fall within a clade composed entirely of members of the genus Betapartitivirus, belonging to the family Partitiviridae. In light of this molecular evidence, TcPV1 is a new member of the genus Betapartitivirus. This is the first report of a new partitivirus hosted by the ascomycete, mycorrhizal fungus T. claveryi.

Keywords: Betapartitivirus; Mycorrhizal fungus; Terfezia claveryi; dsRNA.