engleski

Natural biological control of Cryphonectria parasitica in Croatia

The phytopahogenic fungus Cryphonectria parasitica, the causal agent of chestnut blight, has been responsible for the decline of chestnut trees in all chestnut growing regions of Europe, including Croatia. The aim of this research was to improve understanding of this pathogen diversity and to investigate whether virus-induced hypovirulence is naturally present in C. parasitica populations or human- mediated biological control is necessary.We sampled 338 fungal isolates from 10 chestnut populations throughout chestnut-growing coastal and continental areas of Croatia. Eighten vegetative compatibility (vc) types were identiified, with vc types EU-1, EU-2 and EU-12 being the most widespread. Perithecia and both mating types of C. parasitica in approximately 1:1 ratio were found in all populations suggesting sexual reproduction of the fungus. Although high vc type diversity and sexual reproduction were confirmed, which usually presents an obstade for the spreading of the hypovirus, natural hypovirulence evident in all fungal populations. Incidence of hypovirus- infected isolates ranged from 12.7% in coastal to 66.6% in the continental part of the country. The presence of hypovirus was confirmed not only in all main C. parasitica vc types. But also in some rare vc types. All viral isolates belonged to the Italian subtype of Cryphonectria hypovirus 1 (CHV-1) and were closely related to the isolates found in other European countries.

Cryphonectria parasitica, Cryphonectria hypovirus 1, chestnut blight, hypovirulence, hypovirus-infected isolates

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