Molecular characterization of a new gammapartitivirus isolated from the citrus-pathogenic fungus Penicillium digitatum.

To date, partitiviruses, including gammapartitiviruses, have been extensively studied in various fungal hosts but have not been reported in Penicillium digitatum (also called green mold, the pathogenic fungus infecting citrus). In the present work, we isolated and molecularly characterized a double-stranded RNA (dsRNA) partitivirus from citrus green mold, which we have named "Penicillium digitatum gammapartitivirus 1" (PdGV1). The bisegmented genome of PdGV1 contains two dsRNA segments (dsRNA1 and dsRNA2) with a length of 1795 bp and 1622 bp, respectively. Each of the two genomic dsRNAs contains a single open reading frame encoding a putative RNA-dependent RNA polymerase (RdRp) and a coat protein (CP), respectively. Phylogenetic analysis based on RdRp and CP sequences showed that PdGV1 clustered with mycoviruses belonging to the genus Gammapartitivirus, family Partitiviridae, e.g., Penicillium stoloniferum virus S. The 5'- and 3'-untranslated regions (UTRs) of the PdGV1 genomic dsRNAs both contained unique conserved RNA motifs that have never been found in any other partitivirus. This is the first report of a new gammapartitivirus that infects the citrus-pathogenic fungus P. digitatum.