Detection and tentative grouping of Strawberry crinkle virus isolates

A partial sequence of the putative polymerase (L) protein of Strawberry crinkle virus (SCV), genus Cytorhabdovirus, is described. The virus protein was found to be distantly related to the L protein of the rhabdoviruses Northern cereal mosaic virus, Rice yellow stunt virus and Sonchus yellow net virus. Moreover, a tentative grouping of SCV isolates is described, based on phylogenetic analysis of a region enclosing the GDN-motif within the RNA-dependent RNA polymerase gene. A sequence homology of 98% was found for each tentative group, and heterogeneity of at least 11% was observed between both groups. The tentative grouping did not appear to be related to symptomatology or geographical origin of the isolates. Nevertheless, the use of several reverse-transcription (RT)-PCR primer sets, all directed to different regions within the SCV genome, confirmed the presumptive classification into two groups, namely group I (isolates 1554, KG and Post), and group II (isolates 1553, Hb-A1, 37-1 and 37-2). Additionally, the detection of SCV isolates from herbaceous hosts and strawberry plant material was possible through use of a newly developed gel-based RT-PCR and a gel-free AmpliDet RNA assay. Both methods have the potential to provide rapid, sensitive and specific detection of SCV in in vitro propagation material