Six novel begomoviruses infecting tomato and associated weeds in Southeastern Brazil.

The incidence of tomato-infecting begomoviruses has sharply increased in Brazil following the introduction of the B biotype of the whitefly vector in the early 1990s. Five definitive species and six tentative species have been described since then. Here, we report the detection of members of an additional six novel species, three in tomato and three infecting weeds that are commonly associated with tomato fields: Blainvillea rhomboidea, Sida rhombifolia and Sida micrantha. Tomato and weed samples were collected in two major tomato-growing regions of southeastern Brazil in 2005 and 2007. Two of the novel viruses were present in tomato plants collected in Paty do Alferes, Rio de Janeiro state. Three novel viruses were present in weed samples collected in Coimbra, Minas Gerais state. One virus was present in tomato samples collected at both locations. Genome features indicate that all six species are typical New World, bipartite begomoviruses. However, the viruses belonging to two of the novel species did not cluster with the Brazilian viruses in a phylogenetic tree. These species could represent a distinct lineage of New World begomoviruses, found in Brazil for the first time.