Diversidade, estrutura populacional e caracterização fisiológica de raças de Hemileia vastatrix

• Ano de defesa: 2013
• Autor(a) principal: Cabral, Patrícia Gonçalves Castro
• Orientador(a): Zambolim, Laércio
• Banca de defesa: Rodrigues, Fabrício de ávila , Caixeta, Eveline Teixeira , Capucho, Alexandre Sandri
• 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: Coffea arabica; Coffea canephora; Marcadores moleculares; Ferrugem; AFLP
• Palavras-chave em Inglês: Coffea arabica; Coffea canephora; Molecular markers; Rust; AFLP
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/4415

The fungus Hemileia vastatrix has many physiological races, reflecting in its great genetic diversity. Thirty eight single-pustule isolates of H. vastatrix were characterized in nineteen physiological races. Among them, the races XXIX and XXX were detected for the first time in Brazil. Eleven new physiological races with different combinations of virulence genes, denominated of UFV-Hv-01, UFV-Hv-02, UFV-Hv-03, UFV-Hv-04, UFV-Hv-05, UFV-Hv-06, UFV-Hv-07, UFV-Hv-08, UFV-Hv-09, UFV-Hv-10 and UFV-Hv-11 were also identified. These races do not possess any correspondence with other races of H. vastatrix described in the literature. The genetic structure and diversity of H. vastatrix were analyzed in 115 single-pustule isolates using seven AFLP primers combinations aiming to infer the importance of the host and geographic origin in the genetic structure of the pathogen population. The isolates collected from Coffea arabica, C. canephora, Híbrido de Timor and Icatú derivatives (HDTI) were sampled from five main coffee production Brazilian States. Genotypic diversity in the population of H. vastatrix was low, with 68 patterns AFLP. Genic diversity (h) in the population of H. vastatrix was 0.027 and the random mating possibility was rejected in total population. The lack of correlation between the geographical distance and the genetic similarity (r = -0.024, P = 0.74) suggests the occurrence of urediniospores dispersion to long distances. The genetic differentiation (GST) between H. vastatrix populations defined by host was 0.15 and in the populations defined by States was 0.12. Cluster analysis of AFLP data did not divide the isolates from the same geographical origin and host, neither the same physiological race, although the genetic similarity was above 90%. The molecular analysis of variance revealed that 90% of the genetic distribution occurred between the isolates within the subpopulation. The low level of genetic differentiation in the populations was consistent with the recent introduction of the H. vastatrix in Brazil and the susceptibility of the coffee resistant varieties and derivatives of HDTI to coffee leaf rust. The high level of variation within subpopulations suggests a high evolutionary rate of the pathogen and it may explain the overcoming of resistance of the HDTI derivatives.