Molecular characterization of begomoviruses and DNA satellites from Vietnam: additional evidence that the New World geminiviruses were present in the Old World prior to continental separation.

Sixteen viruses, belonging to 16 species of begomovirus, that infect crops and weeds in Vietnam were identified. Sequence analysis of the complete genomes showed that nine of the viruses (six monopartite and three bipartite) belong to novel species and five of them were identified in Vietnam for the first time. Additionally, eight DNA-beta and three nanovirus-like DNA-1 molecules were also found associated with some of the monopartite viruses. Five of the DNA-beta molecules were novel. Importantly, a second bipartite begomovirus, Corchorus golden mosaic virus, shared several features with the previously characterized virus Corchorus yellow vein virus and with other bipartite begomoviruses from the New World, supporting the hypothesis that New World-like viruses were present in the Old World. This, together with a high degree of virus diversity that included putative recombinant viruses, satellite molecules and viruses with previously undescribed variability in the putative stem-loop sequences, suggested that South-East Asia, and Vietnam in particular, is one of the origins of begomovirus diversity.