engleski

Chestnut blight fungus Cryphonectria parasitica and natural hypovirulence in Croatia

Chestnut is an important forest tree species in Croatia, which is mainly cultivated in coppice forests. Orchards for the production of nuts have a lesser importance and are restricted to the coastal areas of the country. State and privately owned chestnut forests in Croatia are equally represented. Chestnut blight was first observed in 1955 and is now widespread in Croatia. The main goals of this study were to investigate the diversity of the chestnut blight fungus Cryphonectria parasitica and assess the potential for biological control with natural hypovirulence. We sampled 338 isolates from 10 chestnut populations distributed throughout chestnut-growing coastal and continental areas of Croatia. Eighteen vegetative compatibility (vc) types were identified: EU-1 was found to be the dominant vc type reaching a percentage of 42.9%, with EU-2 (21%) and EU-12 (14.2%) following. Perithecia and both mating types of C. parasitica in approximately 1:1 ratio were found in all populations indicating sexual reproduction of the fungus. Natural hypovirulence was also found in all populations with incidence of isolates contained dsRNA ranging from 12.7% in coastal to 66.6% in the continental part of Croatia. All hypovirulent isolates were infected with the Italian subtype of Cryphonectria hypovirus 1 (CHV-1) and were closely related to the isolates found in other European countries.

Castanea sativa; Cryphonectria parasitica; hypovirulence

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