Phylogenetic analysis of Beet necrotic yellow vein virus isolates from China.

A survey detected Beet necrotic yellow vein virus (BNYVV) infection in six Chinese sugar-beet-growing regions. To study the diversity of virus isolates among the regions, nucleotide sequences of four proteins, namely CP, p25, p31, and p26, were determined and the amino acid sequences thus deduced were analyzed using sequence alignments and the phylogenetic method, respectively. Amino acid sequence analysis of CP revealed A-type isolates in Harbin, Hohhot, Baotou, Wuwei, and Jiuquan and B-type isolates in Hohhot and Changji; no Chinese isolate was found to cluster with European P-type isolates. Chinese p25 proteins clustered into three groups with seven tetrad motifs (positions 67-70). Of the seven, the tetrad ASHG has not been reported previously. Most Chinese p31 proteins clustered in p31-2 group, diverging from European p31 proteins. Isolates containing RNA 5 occurred in most of the investigated regions and were associated with both A-and B-types. Phylogenetic analyses of these four proteins showed complex patterns of genetic diversity among these Chinese isolates and indicated that the isolates of China and Japan were more closely related and may have a common origin.