Horizontal transmission of BcPV2 through hyphal contact in pair cultures on PDA. (A) A pair culture on PDA with the colonies of isolate QT5-19 (BcPV2 donor, pink color) and a recipient (gray color). The symbol (*) in the colony indicated the area where a mycelial agar plug was removed and transferred to PDA for establishing a BcPV2-transmitted derivative; (B) Four PDA cultures (20 °C, 20 day) of the B. cinerea isolates free of infection by BcPV2 (BcPV2−); (C) Four PDA cultures (20 °C, 20 day) of the transfected derivatives of B. cinerea. BcPV2+, infected by BcPV2, BcPV2−, not infected by BcPV2.