Isolation and characterization of a novel mycovirus from Penicillium digitatum

- A novel victorivirus designated Penicillium digitatum virus 1 (PdV1) was isolated fromP. digitatum.
- The dsRNA genome of PdV1 are 5211 bp long, two ORFs encoding CP and RdRp, and are encased in virions of ~35 nm in diameter.
- PdV1 infection led to hypovirulent effect on P. digitatum. PdV1 may potentially be used for citrus green mold biocontrol.
- Our study provides a research basis for establishing a model system for the study of P. digitatum-mycovirus interactions.

A novel double-stranded RNA virus designated Penicillium digitatum virus 1 (PdV1) was isolated from the citrus fruit rot pathogen P. digitatum (HS-RH1). The full-length cDNA sequence of the dsRNA/PdV1 (5211 bp) possesses two partially overlapping open reading frames, which encode a coat protein (CP) and a putative RNA-dependent RNA polymerase (RdRp), respectively. Phylogenetic analysis based on multiple alignments of the amino acid sequences of the RdRp and CP indicated that PdV1 tentatively belongs to the genus Victorivirus in the Totiviridae family. Electron micrographs of negatively stained viral particles purified from the peak fraction of sucrose density gradient centrifugation showed spherical particles ~35 nm in diameter. Transfection experiments with purified virions indicated that PdV1 could reduce the vegetative growth and virulence of P. digitatum strain HS-F6. In summary, we report the first isolation and characterization of a mycovirus from P. digitatum that contributes to the hypovirulence phenotypes of the host strain.