|Van Winkle, David|
|Liu, Hsing Yeh|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2007
Publication Date: 9/10/2007
Citation: Weiland, J.J., Van Winkle, D.H., Edwards, M.C., Larson, R.L., Shelver, W.L., Freeman, T.P., Liu, H. 2007. Characterization of a U.S. isolate of Beet black scorch virus. Phytopathology. 97(10):1245-1254. Interpretive Summary: The sugar beet crop in the U.S. has been subjected to increasing disease pressure in recent years, many of which are new to the nation or to production regions. In the fall of 2005, a virus was discovered in a Colorado sugar beet field that had been reported in China, but not previously in the U.S. The genome of the virus, called beet black scorch virus (BBSV), was similar, but not identical, to that reported from northern China. Differences between the two viruses were noted in the genes that are produced enabling the virus to infect plants, to survive in the soil, and to interact with the soil fungus that transmits the virus to plant roots. A DNA clone of the virus was produced that will facilitate the functional characterization of the genes present in the genome. Moreover, inoculations with the cloned version of BBSV will allow accurate assessments for the role of this virus in yield loss in sugar beet to be determined.
Technical Abstract: The first reported U.S. isolate of beet black scorch necrovirus (BBSV) was obtained and characterized. Host range of the virus for localized, and occasionally systemic, infection included the Chenopodiaceae and Tetragonia expansa; Nicotianiana benthamiana supported systemic, symptomless infection of the virus. Rabbit anti-BBSV antiserum with high sensitivity was produced from a purified preparation of the virus. The complete nucleotide sequence of the genomic RNA of the virus, designated BBSV-Co, exhibits 93% similarity to the genome of the 'Ningxia' isolate of BBSV from China. Amino acid sequence similarity in predicted genes ranged from 95% in the p4 gene to 97% in the p82 and coat protein genes. A potential additional gene exists within U.S. isolate of BBSV that is absent from the Chinese isolate of BBSV, due to nucleotide differences within the coat protein gene. Analysis of the coat protein by isoelectric focusing and by mass spectroscopy indicates the presence of phosphorylated resides. Using site-directed mutants of genomic clones of BBSV-Co from which infectious RNA was produced and primer extension analysis of the 5'-end of the genome, the native 5'-end of the BBSV-Co genome was determined to be 5'...3', lacking the two terminal adenosine nucleotides in the published sequences of BBSV from China.