Etiologia da podridão de escama da cebola no semiárido brasileiro

• Ano de defesa: 2015
• Autor(a) principal: OLIVEIRA, Willams José de
• Orientador(a): GAMA, Marco Aurélio Siqueira da
• Banca de defesa: HAM, Jong Hyun, CÂMARA, Marcos Paz Saraiva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• dARK ID: ark:/57462/001300000720m
• Idioma: por
• Instituição de defesa: Universidade Federal Rural de Pernambuco
• Programa de Pós-Graduação: Programa de Pós-Graduação em Fitopatologia
• Departamento: Departamento de Agronomia
• País: Brasil
• Palavras-chave em Português: Etiologia; Podridão das escamas; Podridão de bulbos; Cebola
• Palavras-chave em Inglês: Etiology; Scale rot; Bulb’s rot; Onion
• Área do conhecimento CNPq: FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6063

It was produced approximately 1,601,767 tons of onions in the 2014 harvest in Brazil, and the northeastern region with approximately 23% of this production. The culture of the onion can be affected by various diseases, among them are the bacterial rot. Between the types of decay occurring in onion bulbs stands out the scales rot because it causes significant losses in Brazil. This disease is associated with bacteria from the Burkholderia cepacea complex, Burkholderia gladioli pv. alliicola, Pseudomonas aeruginosa and Serratia marcescens. Given that for the application of efficient management measures it is necessary to understand the etiology of the disease and that it is not known for sure what the genera and species that are associated with the rot of onion scales in the semi-arid northeast, the present study have the following objectives: i) identify the bacteria involved with the disease in this region by sequencing and phylogenetic analysis of 16S rRNA region, ii) evaluate the behavior relatedness of the species identified by rep-PCR, and iii) evaluate the pathological behavior of different species identified. For this purpose, samples were taken in the main producing regions of onion in Pernambuco and Bahia semi-arid region, followed by the isolation and storage of strains in Culture Collection Rosa Mariano (CRM) of the Phytobacteriology Laboratory at the Federal Rural University of Pernambuco. We obtained 45 strains which were grouped into three clades: clade I, containing strains identified as B. cepacia complex (n = 29), clade II containing strains identified as B. gladioli (n = 10) and clade III containing strains identified as P. aeruginosa (n = 6). These strains were submitted to analysis of rep-PCR and were separated into 31 groups with level 70% of similarity. However, it was not possible to identify these three clades by this technique. When artificially inoculated in onion scales, strains of B. cepacia complex and B. gladioli were significantly more aggressive than P. aeruginosa strains. Based on phylogenetic identification performed in this study, it is concluded that the rot of onion bulb scales in the Brazilian semi-arid northeast is caused by the strains of B. cepacia complex, B. gladioli e P. aeruginosa. Moreover, more than one species of the B. cepacia complex may be associated with rot scales in this region.