Characterisation of Cryphonectria hypovirus 1 strains in Turkey and their transmission to various vegetative compatibility types of Cryphonectria parasitica

Abstract

AbstractCharacterization of the Cryphonectria parasitica population was initially done by a phenotypical assessment of 40 in vitro grown isolates obtained from 52 healing cankers collected from eight important chestnut-growing provinces of Turkey. The results of Bavendamm test, often correlated indirectly to hypovirulence, suggested 31 possibly hypovirulent and 9 virulent isolates. PCR tests amplified two regions of ORFs A and B of Cryphonectria hypovirus 1 (CHV-1) from 36 of 40 isolates. The PCR test confirmation was more sensitive than the Bavendamm test. Partial ORFA sequencing revealed 36 CHV-1 haplotypes belonging to Italian subtype (I), with all hypovirulent isolates being of EU-1 vc type. The CHV-1 from 10 native EU-1 isolates were first transferred to six European vc type testers, EU-2, EU-3, EU-5, EU-7, EU-26, and EU-44, having heteroallelism at one vic locus. The presence of the vic locus difference generally reduces virus transmission. The easiest and highest frequency virus transfer was obtained by vic4 and vic6 allelic differences, while the differences vic2 and vic7 made the transfer more challenging. Finally, in this study we successfully transferred CHV-1 to an EU-1 isolate obtained from the Bursa province to an EU-12 European tester isolate.