Identification and Characterization of a Novel Hypovirus from the Phytopathogenic Fungus Botryosphaeria dothidea

Area of Science:

• Mycology
• Virology
• Plant Pathology

Background:

• Botryosphaeria dothidea is a significant plant pathogenic fungus.
• Mycoviruses are increasingly identified in fungal hosts, influencing their biology.
• Understanding the viral landscape of B. dothidea is crucial for disease management.

Purpose of the Study:

• To discover and characterize mycoviruses infecting Botryosphaeria dothidea.
• To identify novel viral species and strains within B. dothidea.
• To investigate the phylogenetic relationships and potential impact of these mycoviruses.

Main Methods:

• High-throughput sequencing was employed to identify mycoviruses in B. dothidea strain SXD111.
• Genome sequencing and assembly were performed for the identified viruses.
• Phylogenetic analyses were conducted to determine viral relationships.
• Transmission experiments and phenotypic observations were used to assess viral impact.

Main Results:

• Three mycoviruses were identified: a novel hypovirus (Botryosphaeria dothidea hypovirus 1, BdHV1/SXD111), Botryosphaeria dothidea polymycovirus 1 strain SXD111 (BdPmV1/SXD111), and Botryosphaeria dothidea partitivirus 1 strain SXD111 (BdPV1/SXD111).
• The genome of BdHV1/SXD111 contains genes for protease, glucosyltransferase, RdRp, and helicase; phylogenetic analysis places it within the Betahypovirus genus.
• BdPmV1/SXD111 has five dsRNA segments, and BdPV1/SXD111 has three dsRNA segments, including a novel satellite component.
• BdHV1/SXD111 is transmissible via conidia and hyphal contact but shows no apparent effect on host morphology or virulence.

Conclusions:

• This study reports the first isolation of a betahypovirus from B. dothidea.
• The discovery of these three mycoviruses significantly broadens the known viral diversity in B. dothidea.
• The findings contribute to a better understanding of virus-fungus interactions in plant pathogens.