engleski

Association between phenotype of hypovirulent Cryphonectria parasitica isolates and Cryphonectria hypovirus 1 sequence variations

The phytopathogenic fungus Cryphonectria parasitica is a causal agent of chestnut blight disease. The invasive pathogen was accidentally introduced from Asia to North America and Europe, where it destroyed a large number of American and European chestnut trees. This severe disease can be controlled by an RNA mycovirus, Cryphonectria hypovirus 1 (CHV1) from the family Hypoviridae. Upon infection, CHV1 causes hypovirulence, reducing sporulation, pigmentation, growth and fertility of the infected fungus. Hypovirulent isolates can promote the recovery of diseased chestnut trees previously infected with the virulent, virus-free isolates of C. parasitica. Since hypovirus infection alters the phenotypic characteristics of the fungal host, the possible association between sequence variation of the viral genome and growth of the hypovirulent C. parasitica isolates was tested. For this purpose, we analyzed partial CHV1 ORF- A sequences, determined the growth rate of hypovirulent fungal isolates and tested association between nucleotide differences in ORF-A sequences and fungal growth rates. Variability of analyzed CHV1 ORF-A sequences was high indicating high genetic diversity among analyzed CHV1 isolates. Growth rates of hypovirulent C. parasitica isolates showed considerable variation as well. An association of growth rate with an SNP within the CHV1 ORF- A sequence was implicated in the statistical analysis. However, variability of this phenotypic characteristic of hypovirulent fungal isolates seems to be only weakly associated with CHV1 ORF-A sequence variability.

chestnut blight ; genetc variability ; growth rate ; mycovirus

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