Genética da resistência à murcha-de-ceratocystis (Ceratocystis fimbriata) em Eucalyptus spp

• Ano de defesa: 2009
• Autor(a) principal: Rosado, Carla Cristina Gonçalves
• Orientador(a): Alfenas, Acelino Couto
• Banca de defesa: Guimarães, Lúcio Mauro da Silva , Lopes, Everaldo Antonio
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Mapeamento genético; Detecção de QTL; Populações exogâmicas
• Palavras-chave em Inglês: Genetic mapping; QTL detection; Exogamous populations
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA VEGETAL
• Link de acesso: http://locus.ufv.br/handle/123456789/4725

The ceratocystis wilt (Ceratocystis fimbriata) is currently, one of the most important diseases in commercial eucalypt plantations in Brazil. The main symptoms are wilting, canker and wood darkening. The use of resistant Eucalyptus genotypes is the best control method. Despite the existence of resistant genotypes, the genetic basis of resistance is unknown. Therefore, the present study aimed to: 1) determine the resistance level of Eucalyptus grandis and E. urophylla genotypes and estimate the possibility to transfer the resistance between these two species through controlled interspecific crosses, 2) build a genetic map, detect and quantify the effects of QTL on ceratocystis wilt resistance using microsatellite markers in an interspecific full sibling family. On the first part of this work five parents of E. grandis and 16 E. urophylla, and 30 progenies E. grandis x E. urophylla (18 to 25 plants per progeny) were evaluated. For resistance screening, five replicates of each parent and each individual progeny, were inoculated under controlled conditions with the SBS-1 C. fimbriata isolate. From 21 parents assessed, twelve were resistant and nine susceptible, independently on the pecies. Estimates of individual narrow (50%) and broad (59%) sense heritability suggested a high degree of genetic control and low allelic dominance of the trait. Wide genetic variation among and within families was detected, a fact that contributes to high heritability and genetic gain. A selection of the 50 clones most resistant in the evaluated families, indicated that the average lesion length in the progeny population can be reduced by 74.4%. On the second part, five replicates of 127 individuals of progeny DGxUGL [(E. grandis x E. dunnii) x (E. urophylla x E. globulus)] were evaluated for ceratocystis wilt resistance. The inoculations were conducted under controlled conditions using the C. fimbriata isolate SBS-1. The resistance response in individuals of the progeny followed a continuously variable allowing to analyze the characteristic quantitatively. Among the 114 microsatellite markers analysed, 110 were mapped on 15 linkage groups (LG), whose lengths ranged from 12.3 to 191.5 cM genetic distance. The genetic map was satisfactory saturated, with total length of 1352.01 cM and an average interval of 12.29 cM. For the simple mark analysis, four markers found located in the GL 3, 5, 8, and 10, had significant effect on the binding resistance QTL (F test, P ≤ 0.05). The method of Fulk & Cardon confirmed the four QTLs found and allowed to identify another one in the LG 1, which heritability ranged from 9.6 to 34.2.