Molecular characterization of Cryphonectria parasitica isolates from Basilicata region (Southern Italy) and mycovirus identification

Chestnut is a valuable species that grows widely throughout the Italian peninsula. It is susceptible to different diseases and among them chestnut blight caused by Cryphonectria parasitica is the most devastating one. This study aimed to molecularly characterize and distinguish virulent and hypovirulent C. parasitica isolates from the Basilicata region. Pure fungal cultures were obtained from symptomatic plant material, their genomic DNA was extracted and amplified using rDNA Internal Transcribed Spacer (ITS), M13 minisatellite and (GACA)4 microsatellite primers. ITS sequencing allowed the identification of the fungal species while minisatellite and microsatellite Polymerase Chain Reactions (PCRs) differentiate between virulent and hypovirulent isolates placing them in distinct clusters. Additionally, sequence analysis of hypovirus partial genome showed that all identified hypoviruses, belonged to Cryphonectria hypovirus 1 (CHV-1) subtype, sharing a 99% sequence identity with the Italian isolate Marche of CHV-1. To our knowledge, this is the first study to differentiate virulent and hypovirulent isolates of C. parasitica at molecular level and identify the hypovirus subtype associated with the hypovirulent isolates in the Basilicata region.