Characterization of a novel botybirnavirus isolated from a phytopathogenic Alternaria fungus

Area of Science:

• Mycology and Virology
• Plant Pathology
• Molecular Biology

Background:

• Alternaria fungi are significant pathogens affecting diverse plant species.
• Mycoviruses, particularly double-stranded RNA (dsRNA) viruses, can influence host pathogenicity and biological characteristics.
• The diversity and host range of mycoviruses are continually expanding with new discoveries.

Purpose of the Study:

• To identify and characterize a novel mycovirus from a phytopathogenic Alternaria sp. strain.
• To determine the genomic features, structure, and phylogenetic relationships of the newly discovered virus.
• To establish the taxonomic placement of the virus within existing viral families.

Main Methods:

• Isolation and purification of virus particles from Alternaria sp. (SCFS-3).
• dsRNA extraction, sequencing, and open reading frame (ORF) analysis.
• Amino acid sequence comparison with known viruses.
• Electron microscopy for particle morphology.
• Phylogenetic analysis based on sequence data.

Main Results:

• A novel dsRNA mycovirus, Alternaria botybirnavirus 1 (ABRV1), was isolated from Alternaria sp. infecting a pear tree.
• ABRV1 possesses two dsRNA segments (6,188 bp and 5,903 bp) encoding two polyproteins with sequence similarities to Sclerotinia sclerotiorum botybirnavirus 1 (SsBRV1).
• Virus particles are isometric and spherical (~40 nm in diameter), composed of putative structural proteins.
• Genomic and phylogenetic analyses place ABRV1 in the newly proposed family "Botybirnaviridae".

Conclusions:

• This study reports the first discovery of a botybirnavirus infecting an Alternaria species.
• ABRV1 represents a significant addition to the known diversity of mycoviruses.
• The findings contribute to understanding the evolution and host interactions of viruses within the proposed Botybirnaviridae family.