Caracterização de isolados de Erwinia Psidii do Distrito Federal e detecção sorológica em goiabeiras

AUTOR(ES)

Ana Cristina Oliveira Teixeira

DATA DE PUBLICAÇÃO

2006

RESUMO

The bacterial blight of guava (Psidium guajava L.) caused by Erwinia psidii is a serious disease affecting orchards in Brazil and it has not been reported in any other country. In Brazil, it was first detected in São Paulo state in 1982. Currently it is present in the Federal District (DF) and three other states (Minas Gerais, Espírito Santo and Paraná). In those production areas it has been considered a major disease, causing significant losses. Control measures are difficult to apply since the pathogen can be easily disseminated. Very little is known about the genetic diversity of E. psidii in Brazil and the objective of this study was to characterize 43 isolates, most of them collected in different orchards in the Federal District. All isolates showed biochemical and nutritional features according to those described for E. psidii. Pathogenicity tests were performed using detached branches and the symptoms were visible from one to nine days after inoculation, depending on the isolate aggressiveness. Genetic diversity among the isolates was evaluated by rep-PCR (REP, ERIC and BOXPCR) which showed high similarity among the Federal District isolates, collected in different orchards and periods. High similarity was also observed between this group of isolates and those from the other three states, including the type strain IBSBF 435. A polyclonal antiserum against the type strain was produced in rabbits and showed high specificity. It was used to optimize a serology-based methodology, using double immunodifusion for early detection of E. psidii in plantlets. Enrichment of the bacterial population directly on guava leaves extracts allowed the detection of the pathogen 36 hours after incubation, even from an initial artificial contamination of 103 ufc/ml.

ASSUNTO(S)

enriquecimento bacteriano erwinia psidii rep-pcr ciências biológicas detecção sorológica goiabeira

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