ssDNA Mycoviruses

Single-stranded DNA (ssDNA) mycoviruses in Botrytis cinerea have been primarily reported within the family Genomoviridae. Virologists identified them using metagenomics and targeted PCR across various regions; the current data better represent a list of known virus types rather than their actual abundance in nature.

Diversity and prevalence

Botrytis cinerea ssDNA virus 1 (BcssDV1), Botrytis cinerea genomovirus 1 (BcGV1) and Botrytis cinerea gemydayirivirus 1 (BcGDV1) have been described infecting the necrotrophic fungus Botrytis cinerea. BcssDV1 was first identified infecting B. cinerea field isolates from Spanish and Italian vineyards, BcGV1 was detected in B. cinerea strains isolated from bean leaves in China, and BcGDV1 was identified in fungal isolates obtained from asymptomatic plants in New Zealand.

Families and characteristics

Family / Group Genome Structure Characteristics
Genomoviridae Circular ssDNA (2,089–2,290 nt in related putative viruses) Circular single-stranded DNA viruses have a circular ssDNA genome encoding a replication-initiation protein (Rep) and a capsid protein (CP), and contains a stem-loop structure with the nonanucleotide TAATATTAT that is likely important for rolling-circle replication. The virions are non-enveloped, isometric, 20–22 nm in diameter, and the virus infects fungi; many related putative viruses were also reported from diverse environmental and animal-associated samples, although their hosts remain unknown.

Effects on fungal host

Genomoviruses such as BcGDV1 can reduce fungal growth and virulence, causing slower colony expansion and smaller lesions in infected plants, a phenomenon known as hypovirulence.

Ecological significance and impact

These viruses interact with the host defence system, which limits their replication through RNA silencing and DNA methylation, resulting in low virus levels and potentially stable long-term infections that may be useful for biological control of fungal pathogens.

Evolutionary history

Genomoviridae exhibit conserved motifs within the replication-associated protein (Rep) that facilitate rolling-circle replication. Reps sequences of BcssDV1, BcGV1 and BcGDV1 shared an identity of 98% among them, so according to demarcation criteria they should be considered as members of the same viral species.

Nucleotide alignment

Primary structure alignment (amino acids)

Phylogeny