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Isolation and Characterization of Brenneria quercina, Causal Agent for Bark Canker and Drippy Nut of Quercus spp. in Spain

April 2003 , Volume 93 , Number  4
Pages  485 - 492

Elena G. Biosca , Raquel González , María José López-López , Santiago Soria , Carmina Montón , Eduardo Pérez-Laorga , and María M. López

First, second, third, and seventh authors: Instituto Valenciano de Investigaciones Agrarias, Moncada, 46113, Valencia, Spain; fourth author: Patrimonio Nacional, Palacio Real, 28071, Madrid, Spain; fifth author: Laboratori de Sanitat Vegetal, DARP, 08040, Barcelona, Spain; and sixth author: Servicio de Gestión Forestal, Consellería de Medio Ambiente, 46011, Valencia, Spain

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Accepted for publication 10 December 2002.

The drippy nut disease of oak was first described in California in 1967 and, since then, the causal agent has not been reported in any other area. This study describes for the first time in Europe the isolation of Brenneria (Erwinia) quercina from bark canker in addition to drippy bud and drippy nut in Quercus ilex and Q. pyrenaica. The bark canker and drippy bud symptoms were not previously described as caused by this bacterium. No fungal pathogens were associated with any of the symptoms. Physiological and biochemical characterization identified the pathogenic isolates from Spain as belonging to B. quercina, similar to the reference strain CFBP 1266. Fatty acid profiles of the Spanish isolates also were similar to the strain of B. quercina from California. Serological analysis by indirect immunofluorescence and enzyme-linked immunosorbent assay using polyclonal antisera against the reference strain of B. quercina and one Spanish oak isolate revealed some antigenic heterogeneity between isolates of different origins. Pathogenicity tests demonstrated that the Spanish isolates were able to reproduce internal symptoms of necrosis and acorn exudation in Q. ilex and Q. pyrenaica and suggest that B. quercina may be associated, among other causes, with the oak decline syndrome affecting Spanish oak forests.

Additional keywords: inoculation, phenotypic, serology.

© 2003 The American Phytopathological Society