Molecular characterization and phylogenetic analysis of two distinct strains of<i>Blueberry scorch virus</i>from western Canada

Abstract

A disease affecting cultivated highbush blueberry (Vaccinium corymbosum) was first reported in the Fraser valley of British Columbia in 2000. Symptoms were similar to those of the disease caused by the Blueberry scorch virus (BlScV), and the diagnosis was supported by an enzyme-linked immunosorbent assay (ELISA), using a polyclonal antibody. Two BlScV-positive plants that exhibited characteristic symptoms were collected from two separate fields. Both isolates were mechanically transmitted from their original blueberry host to Nicotiana occidentalis, a recently discovered herbaceous host for BlScV, and sequenced. These two isolates were designated BC-1 and BC-2. BC-1 and BC-2 shared, respectively, 83% and 77% genome sequence identity with BlScV strain NJ-2. Comparison of individual genes with those of NJ-2 revealed 81%–90% sequence identity for BC-1, and 74%–85% identity for BC-2. Phylogenetic analysis was performed on a portion of the coat protein (CP) gene from BC-1, BC-2, NJ-2, and five partially sequenced BlScV isolates obtained from GenBank. Results indicated that BC-1 and BC-2 are two distinct strains of BlScV, possibly suggesting two separate introductions of the virus into British Columbia. The discovery of novel strains of BlScV in British Columbia may affect management of the disease in blueberry crops, and the characterization of these strains could be used to improve diagnostic tools for monitoring.