Herança e mapeamento de QTLs da resistência do Híbrido de Timor à ferrugem do cafeeiro

• Ano de defesa: 2008
• Autor(a) principal: Capucho, Alexandre Sandri
• Orientador(a): Zambolim, Laércio
• Banca de defesa: Pereira, Antonio Alves , Sakiyama, Ney Sussumu
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Hemileia vastatrix; Resistência; Microssatélites
• Palavras-chave em Inglês: Hemileia vastatrix; Resistance; Microsatellites
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/4361

The objectives of this work were to study the resistance inheritance of the Híbrido Timor UFV 443-3 to Hemileia vastatrix and identify QTLs associated with resistance to coffee leaf rust. To study the inheritance we used a population of 246 individuals, produced from the controlled self-pollinated F1 H 511-1, 115 susceptible backcrossing (BCS) plants, and 87 resistant backcrossing (BCR) plants, originated from the crossing between F1 with Catuaí amarelo UFV 2148-57 and Híbrido de Timor UFV 443-3, respectively. These populations were inoculated with the race II, and a noncharacterized field isolate, designated pathotype 001, both from a single pustule-isolate of H. vastatrix. For both pathotypes, the Catuaí amarelo UFV 2148-57 was susceptible, while the Híbrido de Timor, the F1, and the BCR plants were resistant. The F2 plants inoculated with the race II showed two goodness of fit by the chi-square test, 15:1 (P=24.92%) and 61:3 (P=87.27%). The resistance inheritance was confirmed by the inoculation of BCs plants which segregated in a rate of 3:1 (P=17.83%), expected for the two genes, whereas the hypothesis of segregation 7:1, expected for three genes, was rejected. These results demonstrate that two independent dominant genes are responsible for the resistance of the Híbrido de Timor 443-3 to the race II of H. vastatrix. Similar results were observed with the pathotype 001 showing a segregation of 15:1 (P=92.13%) in the F2, and 3:1 (P=78.78%) in the BCs. These data indicate that two independent dominant genes, also, control the resistance of the Híbrido de Timor to this pathotype. To identify QTLs associated with the resistance of the Híbrido de Timor UFV 443-3 to coffee leaf rust we tested 286 molecular markers (282 SSR and 4 RAPD) in the parental genotypes. Those polymorphic markers (21 SSR and 4 RAPD) were used to screening the 246 F2 plants and to construct the linkage map. Among the 25 analyzed markers, two did not match to any of the six linkage groups formed by the 23 remaining markers, covering 277.90cM of the genome. Three QTLs were identified, QTLHv1, QTLHv2 and QTLHv3, that explain, 5.94%, 5.52% and 15.92% of the phenotypic variation respectively. The LOD score and the recombination frequency between the marker and respective QTLs were 3.69 and 14cM to the QTLHv1, 3.18 and 0.5cM to the QTLHv2, and 10.33 and 22cM to the QTLHv3. This is the first report of SSR markers in the identification of QTLs associated to the coffee tree resistance to H. vastatrix. These QTLs could be used in the assisted selection for introgression of genes for resistance from the Híbrido de Timor UFV 443-3 to coffee leaf rust into commercial genotypes.