Amino acid differences in the N-terminal half of the polyprotein of Chinese turnip mosaic virus isolates affect symptom expression in Nicotiana benthamiana and radish

Authors: HU, WEN-XING - Chungnam National University; SEO, EUN-YOUNG - Chungnam National University; CHO, IN-SOOK - Chungnam National University; KIM, JUNG-KY - Chungnam National University; JU, HYE-KYOUNG - Chungnam National University; KIM, IK-HYUN - Chungnam National University; CHOI, GO-WOON - Chungnam National University; KIM, BORAM - Chungnam National University; AHN, CHUN-HEE - Chungnam National University; Domier, Leslie; Hammond, John; LIM, HYOUN-SUB - Chungnam National University

Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2019
Publication Date: 4/8/2019
Citation: Hu, W., Seo, E., Cho, I., Kim, J., Ju, H., Kim, I., Choi, G., Kim, B., Ahn, C., Domier, L.L., Hammond, J., Lim, H. 2019. Amino acid differences in the N-terminal half of the polyprotein of Chinese turnip mosaic virus isolates affect symptom expression in Nicotiana benthamiana and radish. Archives of Virology. 164(6):1683-1689. https://doi.org/10.1007/s00705-019-04242-9.
DOI: https://doi.org/10.1007/s00705-019-04242-9

Interpretive Summary: Plant virus infections cause reductions in yield and quality in many crops, and may be spread within the crop by horticultural operations or by insects or other vectors. New virus isolates may arise by mutation, or by movement into the crop, often being carried long distances by wind-blown insect vectors, or by seed transmission. Many viruses are important in crops in both China and Korea, and may be spread by seed transmission or insect vectors. Four new isolates of Turnip mosaic virus (TuMV) from radish crops in China were characterized; three were most similar to a previously described Chinese isolate, and the fourth was most similar to an isolate from Korea. Differences in pathogenicity were related to a small number of variant amino acids in three viral genes, with one single amino acid difference associated with a necrotic symptoms. Knowledge of TuMV isolate variability will aid plant breeders to select new resistance genes, and aid farmers and extension personnel to select crop varieties carrying different resistance genes.

Technical Abstract: In 2017, we performed a survey in radish fields in northern China, and generated four infectious clones (CN3, CN7, CN8, and CN9) of TuMV from the isolates collected. Genomic sequence of these four isolates was determined, showing 90.53%~99.96% nucleotide identity, and 97%~99.94% amino acid identity. Among these four isolates, CN7, CN8, CN9 were most closely related to Chinese isolate CCLB (KR153038), and CN3 most closely related to Korea isolate HJY1 (KX674727). Phylogenetic analysis of TuMV genomic sequences showed that all four isolates were clustered into the basal-BR group. A few differential amino acids in the N terminal half of the polyprotein (in P1, HC-Pro and CI) of these isolates resulted in varied symptom development in Nicotiana benthamiana; although CN3 had the most divergent polyprotein sequence, the symptoms induced by CN3 and CN9 were the most similar among the four isolates. Among the few residues differentiating CN7, CN8, and CN9, a single CI residue unique to CN7 may be associated with the observed stem necrosis induced by this isolate.