Variabilidade e estrutura genética de populações de begomovírus em tomateiro e plantas daninhas em seis localidades do sudeste brasileiro

• Ano de defesa: 2011
• Autor(a) principal: Rocha, Carolina da Silva
• Orientador(a): Zerbini Júnior, Francisco Murilo
• Banca de defesa: Paula, Sérgio Oliveira de , Ribeiro, Simone da Graça , Mizubuti, Eduardo Seiti Gomide , Urquiza, Gloria Patricia Castillo
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Begomovírus; Variabilidade; Tomateiro
• Palavras-chave em Inglês: Begomovírus; Variability; Tomatoes
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA MOLECULAR E DE MICROORGANISMOS
• Link de acesso: http://locus.ufv.br/handle/123456789/1336

The incidence of begomoviruses has sharply increased in Brazil since the mid 1990 s, after the introduction of the B biotype of the whitefly Bemisia tabaci. It is believed that the insect vector transferred indigenous viruses infecting wild and weed hosts to tomato. After a rapid evolutionary process, novel species adapted to the new host became prevalent in the field. The objective of this work was to determine the genetic structure of begomovirus populations infecting tomatoes and weeds in major tomato growing regions of southeastern Brazil. Tomato and weed samples were collected at six locations in the states of Rio de Janeiro and Minas Gerais, from May 2005 to May 2010. A total of 126 DNA-A and 58 DNA-B full-length begomovirus components were amplified using rolling-cicle amplification, cloned and sequenced. Two isolates of the tentative species Tomato mottle leaf curl virus (ToMoLCV) were associated with tomato plants collected in Jaíba, MG. This virus had not yet been recognized as a distinct species because its DNA-A had not been completely sequenced. The complete DNA-A sequence and molecular characterization of the two isolates from Jaíba indicate that ToMoLCV is a typical New World, bipartite begomovirus with greater sequence identity with begomoviruses from Brazil. Phylogenetic analysis confirmed the relationship of ToMoLCV with New World begomoviruses from Brazil. Together, these results support the classification of ToMoLCV as a new species in the genus begomovirus. Besides ToMoLCV, eight begomoviruses were detected in tomatoes and eight begomoviruses in the weed samples, with four viruses present in both tomatoes and weeds. All of these viruses had been previously described and are restricted to Brazil. Their sequence features indicate that they are typical New World, bipartite begomoviruses. Two viruses (SiYLCV and ToCmMV) cluster with non-Brazilian viruses in phylogenetic trees. Recombination analysis confirmed the mosaiclike nature of Brazilian begomoviruses. Many of the recombination events involving tomato viruses had weed viruses as putative parents. Viral populations were structured with subdivisions based on location, and highly variable, with the weed-infecting BlYSV displaying higher genetic variability compared to the tomato-infecting ToCmMV, ToCMoV, ToSRV and ToYVSV.