Set-up of a biocontrol experiment with genetically characterized hypovirus-infected Cryphonectria parasitica strains

Abstract

For a better understanding of its dissemination, the Cryphonectria hypovirus has been artificially introduced into two different C. parasitica populations. Chestnut blight cankers were treated with a hypovirus-infected strain. In one population (Choex, Valais) hypovirulence was absent before the treatment, whereas in the other (Claro, Ticino) it was already naturally present. The aim of the experiment was to track the introduced virus as well as its fungal carrier and to survey the dynamic of the disease in these stands. In Choex, where no other viruses were present, the virus is easily detected by verifying the virus-associated culture morphology of the isolated strains. In Claro, RFLPs of two fragments amplified from the reverse transcribed viral genome (RT-PCR) serve as markers to distinguish the introduced virus from the resident hypoviruses. Similarly, a DNA fingerprinting method is used to identify the introduced fungal strain.