Low Genetic Diversity Suggests a Single Introduction and Recent Spread of T omato chlorosis virus in B razil

By comparing the partial nucleotide sequences of the heat shock protein HSP 70 homologue gene, we assessed the genetic diversity of B razilian tomato isolates of T omato chlorosis virus (To CV ), as well as their relationship with other To CV isolates found worldwide. The B razilian To CV isolates shared 99.9–100% nucleotide identity, which indicates low genetic diversity. B razilian To CV isolates showed a closer evolutionary relationship to those from Mediterranean countries. Based on these results, the origin of B razilian To CV isolates and the possible number of introductions of the virus into B razil are discussed.