Molecular detection and genotype identification of Brassica yellows virus in Guizhou

【Objective】Molecular detection and genotype identification of Brassica yellows virus(BrYV) infection in Chinese cabbage, radish and cabbage in Guizhou were conducted to provide reference for control of potato leaf curl virus.【Method】284 samples of vegetable(Chinese cabbage, radish and cabbage) virus diseases were collected in Zunyi, Weining, Guanling, Pingba and other cities(counties) in Guizhou. RT-PCR molecular detection using the common primers of potato leaf curl virus was conducted and P0 and CP gene sequences amplification was conducted with the 16 BrYV isolates detected, then compared to the reported BrYV gene sequences. Phylogenetic tree was constructed and its genotype was identified.【Result】BrYV was detected in 43 suspected samples out of 284 virus disease samples, and the positive rate was 15.14%. Among them, there were 12 BrYV infected samples in cabbage samples, accounting for 12.77% of the total number of cabbage samples;14 BrYV infected samples in radish samples, accounting for 20.29% of the total number of radish samples;17 BrYV infected samples in cabbage samples, accounting for 14.05% of the total number of cabbage samples. The nucleotide similarity of P0 gene and CP gene of 16 BrYV isolates were 89.9%-100.0% and 93.5%-100.0%, respectively. The consistency of amino acids sequence was 100.0%. Phylogenetic tree based on P0 gene showed that, BrYV-Pingba-BC-2, BrYV-Zunyi-LB-1, BrYV-Zhijing-BC-1, BrYV-BJS and BrYV-BBJ were clustered into one branch, and the other 13 isolates were clustered into one branch with BrYV-ABJ and BrYV-AJS. There was no obvious boundary between 16 BrYV isolates and BrYV-A and BrYV-B genotypes from different vegetable crops in different areas of Guizhou according to Phylogenetic tree based on CP gene, and the genetic relationships were all relatively close. Five recombination events were detected in BrYV P0 gene and no potential recombination events were detected in BrYV CP gene.【Conclusion】BrYV is prevalent in Chinese cabbage, radish and cabbage in Guizhou, but the damage radish is the most serious, there are two genotypes of BrYV-A and BrYV-B.