Detection of European mountain ash ringspot-associated virus (EMARAV) in Sorbus aucuparia L. by a specific antiserum and reverse transcription-PCR

Chlorotic ringspots and mottling on leaves of European mountain ash (Sorbus aucuparia L.) are typical symptoms of the widely distributed ringspot disease. We found a novel plant RNA virus with a multipartite genome associated with these symptoms, called European mountain ash ringspot-associated virus (EMARAV). This virus is not classified yet but shows certain similarities to members of the virus family Bunyaviridae. Characterization of the complete viral genome of EMARAV allowed us to develop two sensitive procedures, which enable the specific detection in its host plant. By raising an antiserum against the N-terminal part of the putative nucleocapsid protein p3, the detection of EMARAV, respectively its proteins, in leaf extracts is now feasible. A second diagnostic tool, the reverse transcription-PCR (RT-PCR), allows the detection of EMARAV with even higher sensitivity. One specific primer pair was deduced from each of the four viral genomic RNAs to amplify minute amounts of the virus in various plant tissues.