Sequence analysis of CP and HC-Pro genes of Turnip mosaic virus isolates from China.

Fourteen isolates of Turnip mosaic virus (TuMV) were obtained from the leaves of diseased cruciferous plants in China. According host tests, the isolates were classified into B-host and BR-host group. The nucleotide sequences of the coat protein (CP) and helper component proteinase (HC-Pro) genes of the isolates were determined. The CP genes consisted of 864 nucleotides encoding a polypeptide of 288 amino acids. The HC-Pro genes comprised 1374 nucleotides encoding a polypeptide of 458 amino acids. The genes CP and HC-Pro of the 14 isolates shared nucleotide sequence identities ranging from 89.2 to 99.5% and 79.1 to 99.9%, respectively. Amino acid sequence identities of CP and HC-Pro proteins ranged from 95.1 to 100% and 94.8 to 99.8%, respectively. Phylogenetic tree based on the CP gene indicated that 13 of the 14 TuMV isolates belonged to the world-B group, while the remaining isolate ZJ1 belonged to the basal-BR group. The phylogenetic tree based on the HC-Pro gene was similar to that of CP gene with the exception of the isolate JX that clustered with the Asian-BR group. Our results were consistent with the previous results demonstrating that a majority of the isolates collected from Brassica spp. belonged to the world-B group.