Patogenicidade de populações de Meloidogyne incognita, provenientes de Minas Gerais e São Paulo, ao cafeeiro

• Ano de defesa: 2006
• Autor(a) principal: Oliveira, Dagoberto Saunders de
• Orientador(a): Oliveira, Rosângela D arc de Lima
• Banca de defesa: Freitas, Leandro Grassi de , Pereira, Antonio Alves , Meira, Renata Maria Strozi Alves , Rodrigues, Fabrício de ávila
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Café; Nematóide-das-galhas; Meloidogyne incognita; Resistência; Histopatologia; Coffea arabica
• Palavras-chave em Inglês: Coffee; Nematodes; Meloidogyne incognita; Resistance; Histopathology; Coffea arabica
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1065

The four existing races of Meloidogyne incognita, although infecting various crops and weeds in the Minas Gerais State, have not been detected in coffee trees, differently from what happens in other coffee producing areas of Brazil, in which the rootknot nematode is one of the main limiting factors for the coffee cultivation. The reasons that explain such phenomenon are still unknown, because the most common coffee cultivars (Catuaí and Mundo Novo) in Minas Gerais are susceptible to all races of these nematode species. For this reason, the objective of this work was to study possible factors responsible for the non-establishment of M. incognita in coffee plantations in Minas Gerais. Initially, populations of M. incognita original from Minas Gerais were compared to populations original from São Paulo, which are proved to be pathogenic to coffee. They were all identified as M. incognita by morphological, physiological, molecular and isozyme analysis, hence, the observed difference in the pathogenicity of the populations of the two States was not due to previous misidentification of the species. After the identity confirmation of the Minas Gerais nematode populations, the lack of pathogenicity of them was evaluated by inoculating populations of the four races of M. incognita under different temperature regimes, different inoculum densities, in plantlets of different developmental stages and in different coffee genotypes. The four M. incognita races original from Minas Gerais were incapable of reproducing in the coffee plantlets, independently of the inoculum concentration, temperature, plant stage and coffee genotype. Since the Minas Gerais populations incapacity of infection was confirmed, the mechanisms involved in this incompatible interaction were tried to be elucidated, evaluating the root penetration, the post-infective nematode development and the root histological alterations caused by one of the non-pathogenic population. The mechanisms that conferred incompatibility between Minas Gerais population of M. incognita and coffee actuated primarily in the juvenile penetration phase, causing reduction in the penetration and evasion of the juvenile from coffee roots. Furthermore, post-penetration mechanisms prevented giant cell formation, impeding the nematode development in the coffee tree. The results lead to the conclusion that the Minas Gerais populations of M. incognita belong to a biotype different from those found in other coffee producing areas in Brazil.