Watermelon chlorotic stunt virus from the Sudan and Iran: Sequence comparisons and identification of a whitefly-transmission determinant

The genomes of two Watermelon chlorotic stunt virus (WmCSV) isolates, one from the Sudan and one from Iran, were cloned and sequenced. Sequence relationship with other geminiviruses characterizes WmCSV as a typical Eastern Hemisphere geminivirus with a bipartite genome. The two geographically distant WmCSV isolates from Africa and the Middle East share a very high overall sequence similarity: 98% between their DNA-A and 96% between their DNA-B components, and their respective capsid proteins are identical. A single amino acid change in the capsid protein (NI31D) renders WmCSV whitefly nontransmissible. This region of the capsid is also implicated in transmission by Bemisia tabaci of Tomato yellow leaf curl virus.