Characterisation of Cryphonectria parasitica, the casual agent of chesnut blight, and Cryphonectria hypovirus isolates obtained from different regions of Turkey

Hundred-eighty-three Cryphonectria parasitica isolates were obtained from 215 infected chestnut bark samples collected from 13 different locations having significant chestnut production. Based on the cultural characteristics, 143 of these isolates were classified as virulent and the rest 40 were hypovirulent. Majority of the C. parasitica isolates, 135 out of 183 (82.32%) morphologically determined as EU-1 of the European vegetative compatibility type, while 29 (17.68%) were EU-12. The remaining nineteen isolates did not match any of the two vc types (EU-1 and EU-12). Molecular vc distinction of the isolates gave almost similar results, 149 (81.42%) of them being EU-1 and 34 (18.58%) of them EU-12. Mating types of the C. parasitica isolates were also determined by using molecular methods and 73.2% (134 isolates) was belong to MAT-1 and 24% (44 isolates) was MAT-2 while 2.8% (5 isolates) showed both of the MAT types. Sequence analysis showed that all 19 viral isolates belonged to Italian subtype I of Cryphonectria hypovirus 1 (CHV1). All the hypovirulent isolates were EU-1 vc type. The hypovirus, found in 10 Turkish EU-1 isolates was transmitted to the isolates of six vc types; EU-2, EU-3, EU-5, EU-7, EU-26 and EU-44, which were found in Turkey at low percentages and has one different allele in turn in the six known di-allelic vic loci. By this way, Turkish CHV1 subtype I was also transmitted to the European vc type EU-12 for the first time. Two different markers systems (iPBS ve SCoT) were used to evaluate the polymorphism among the C. parasitica isolates, all of them were found structurally clonal without any polymorphism.