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Molecular and Biological Characterization of Tomato chlorotic mottle virus Suggests that Recombination Underlies the Evolution and Diversity of Brazilian Tomato Begomoviruses

First, third, fourth, and fifth authors: Embrapa Recursos Genéticos e Biotecnologia, Parque Estação Biológica, CEP 707770-900, Brasília, DF, Brazil; first and third authors: Laboratory of Virology, Wageningen University, Wageningen, The Netherlands; second author: Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Observatory, Cape Town, 7925, South Africa; and sixth author: Embrapa Hortaliças Cx. Postal 218, CEP 70359-970, Brasília, DF, Brazil.

Tomato chlorotic mottle virus (ToCMoV) is an emerging begomovirus species widely distributed throughout tomato-growing regions of Brazil. ToCMoV appears to have expanded its geographic range recently, invading tomato-growing areas that were free of begomovirus infection before 2004. We have determined the first complete genome sequence of an infectious ToCMoV genome (isolate BA-Se1), which is the first begomovirus species isolated in the northeast of Brazil. When introduced by particle bombardment into tomato, the cloned ToCMoV-[BA-Se1] DNA-A and DNA-B components caused typical chlorotic mottle symptoms. The cloned virus was whitefly-transmissible and, although it was infectious in hosts such as Nicotiana benthamiana, pepper, tobacco, and Nicandra physaloides, it was unable to infect Arabidopsis thaliana, bean, N. glutinosa, and Datura metel. Sequence and biological analyses indicate that ToCMoV-[BA-Se1] is a typical New World begomovirus sp. requiring both DNA-A and DNA-B components to establish systemic infections. Although evidence of multiple recombination events was detected within the ToCMoV-[BA-Se1] DNA-A, they apparently occurred relatively long ago, implying that recombination probably has not contributed to the recent emergence of this species.