First report of European mountain ash ringspot-associated emaravirus (EMARaV) in Bastard Whitebeam (Karpatiosorbus x hybrida). EMARaV in Bastard Whitebeam

We report the first detection of European mountain ash ringspot associated emaravirus (EMARaV) in Karpatiosorbus x hybrida (Borkh.) Sennikov & Kurtto (Bastard Whitebeam) in Finland. We sampled leaf material from six Bastard Whitebeam shrubs cultivated in a public park in the city of Helsinki, Finland, showing chlorotic ringspots, mottle, line patterns, sometimes accompanied by leaf deformation and decline. We could demonstrate that six Bastard Whitebeams and the rowan were affected by an emaravirus by amplification of a 360 bp fragment from the sampled leaf material using generic primers targeting RNA1 (Elbeaino et al. 2013). Additionally, EMARaV-specific RT-PCRs (von Bargen et al. 2019) detected RNA2-RNA4 and RNA6 of the virus in the corresponding samples, while none of the genome segments were detectable in the Whitebeam sample taken from a tree without leaf symptoms. By sequencing of PCR products amplified from viral RNA1 and RNA4 we could confirm that all Whitebeams with leaf symptoms are infected. This is the first record of EMARaV affecting Bastard Whitebeam in Finland. The rowan tree growing adjacent to the Whitebeams was infected by the virus, with the putative vector P. pyri also being found on the tree. by EMARaV.