engleski

Diversity of Cryphonectria hypovirus 1 in Croatia: impact on its fungal host

Cryphonectria parasitica is the causal agent of chestnut blight, a severe disease responsible for the decline of chestnut trees. However, this aggressive fungus can be infected with naturally occurring Cryphonectria hypovirus 1 (CHV-1). Hypovirus CHV-1 is unencapsidated dsRNA virus, one of four species that belong to family Hypoviridae. CHV-1 reduces fungal virulence and sporulation, consequently causing healing of cankers and recovery of infected trees. This phenomenon is called hypovirulence and it provides the basis for biological control of chestnut blight. The hypovirus can be transmitted horizontally from infected to non-infected C. parasitica strains via hyphal anastomosis and vertically into asexual conidia, but not into sexual ascospores. CHV-1 isolates from Croatia were characterized by sequencing part of the genomic ORF-A and the effect of virus isolates on the fungal host was assessed by measuring growth of CHV-1-infected C. parasitica strains on chestnut stems. Although all virus isolates from Croatia belonged to the Italian subtype of CHV-1, their effect on fungal host was significantly different. The results of other scientific groups imply that CHV-1 isolates that belong to Italian subtype have weaker effect on its fungal host compared to French subtype isolates. However, our results reveal that one CHV-1 isolate sampled on island Cres had strong effect on fungal growth, similar to the strong French isolate EP713-CHV-1.

chestnut; Cryphonectria parasitica; hypovirus

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