IDENTIFICATION AND SEQUENCE ANALYSIS OF TURNIP MOSAIC VIRUS INFECTION ON CRUCIFEROUS CROPS IN SOUTHWEST OF CHINA

Eleven samples were randomly collected from cruciferous plants with green or yellow mosaic symptoms in different areas of the Sichuan province (southwest China). The virus recovered from all samples was recognized as a possible potyvirus by electron microscope observations (negative staining and ultrathin sections) and identified as Turnip mosaic virus (TuMV) by RT-PCR. The coat protein (CP) gene of these isolates was cloned and sequenced. Sequence comparisons showed that these isolates shared 97-100% identity among themselves at the nucleotide level, whereas the identity level with TuMV strains isolated from other parts of China was 89-99.2%. Phylogenetic analysis of the CP sequences revealed that Sichuan isolates clustered in the world-B group. The results also showed that TuMV is a common pathogen of various cruciferous crops in the Sichuan province.