Identificação de fonte de resistência ao pepYMV em acessos de tomateiro cultivado e silvestre do banco de germoplasma de hortaliças da UFV, análise da herança da resistência e alterações estruturais nos tecidos infectados

• Ano de defesa: 2006
• Autor(a) principal: Juhász, Ana Cristina Pinto
• Orientador(a): Silva, Derly José Henriques da
• Banca de defesa: Zerbini Júnior, Francisco Murilo , Carneiro, Pedro Crescêncio Souza , Meira, Renata Maria Strozi Alves , Rodrigues, Rosana
• 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: Tomate; Resistência; Geminivirus
• Palavras-chave em Inglês: Tomato; Resistance; Geminivirus
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1290

The identification of resistance sources to diseases and the knowledge of the genetic control of resistance is one of the first steps in a genetic improvement program aiming the obtention of resistant cultivars. The potivirus Pepper yellow mosaic virus (PepYMV), recently identified in tomato plants in Brazil, has disseminated quickly and it has a potential to become a serious problem to the tomato cultivation in the country. This work had the aim to identify the resistance sources to PepYMV in 376 accessions of Lycopersicon sp. (Solanum sp.) from the Vegetable Crops Germoplasma Bank of UFV (BGH-UFV), to make a study of resistance heritage and to investigate the alterations on the tomato plant leaves caused by the viral infection. From the 355 accessions of L. esculentum (Solanum lycopersicum) from BGH-UFV, inoculated with the PepYMV, none of them was considered a safe source of resistance, for having a high viral content when evaluated by means of indirect ELISA. Among the 21 accessions on wild species of analyzed tomato plants, one accession of L. hirsutum (BGH 6902) was selected and considered resistant, for did not show any symtoms and for having no viral infection. A sum of 540 plants from the P1, P2, F1, F2, RC1:1 and the RC1:2 generations was evaluated, obtained from the Santa Clara x BGH 6902 intercrossing. The plants were inoculated mechanically and the viral concentration of PepYMV on each plant was determined by the absorbance reading obtained from indirect ELISA testing. Considering the segregation rate of resistant plants to the susceptible, the hypothesis of 1:3 as well as of 3:13 were not significative by the chi-square test, with x2 = 1,35 for the hypothesis of a recessive gene and x2 = 0,69 for the hypothesis of two genes with epistatic influence, and herdability = 99%. However, the hypothesis of only one gene was confirmed by the self fertilization and the evaluation of some plants resistant to F2, it was concluded with 98,32% of certainty that only one gene is involved in the resistance of L. hirsutum to PepYMV. On the assymptomatic resistant access (BGH 6902) no histological alterations on the leaves were observed. On the Santa Clara plants, the disease symptoms were severe, as well as on the susceptible plants from the F2 generation, on which the anatomic structure of the leaf tissues was quite affected. On the F1, generation plants, despite the slight expression of symptoms, it was not possible to visualize any alteration at a cell level. It was observed that the virus caused serious damages, morfologically as much as anatomically, to the infected leaves of susceptible plants, indicating the severity of the disease.