Identification and characterization of hypovirus-infected Cryphonectria parasitica isolates from biological control plots in İzmir, Kütahya, and Sinop

Abstract

In a pilot study, a biological control with hypovirus-infected Cryphonectria parasitica was applied in 3 study plots in Turkey,in June 2013. The aim of this study was to evaluate the success of the applied biological control by verifying the establishment of thereleased hypovirus (CHV-1) strains using molecular markers. C. parasitica isolates were sampled from cankers at 3 different time points:before the biological control treatments (April 2013), and 5 months (October 2013) and 11 months (May 2014) after the treatment. Intotal, 255 C. parasitica isolates were recovered and characterized. First, the culture morphology and vegetative compatibility type ofthese isolates were assessed. Next, the presence of hypoviruses in white isolates was checked by RNA extraction and subsequent RTPCR. Finally, a sequence analysis was performed to compare the hypoviruses to the released biological control hypoviruses by examiningsingle nucleotide markers and reconstructing their phylogenetic relationship. The study sites in İzmir and Kütahya were found to befree of hypoviruses prior to the biological control, whereas in Sinop, the occurrence of hypoviruses of the Italian subtype was observed.Reisolations of the treated cankers and subsequent molecular analysis resulted in the detection of the released biocontrol hypovirusstrains in all 3 study sites. The reisolated hypoviruses in İzmir and Kütahya originated from either one of the released biocontrol strains.In Sinop, both natural and artificially introduced hypoviruses were detected. Our study showed that the released biological controlhypoviruses persisted in the treated cankers, which is promising for the biological control of chestnut blight in Turkey