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Analysis of Gene Expression in Two Growth States of Xylella fastidiosa and Its Relationship with Pathogenicity

October 2003 , Volume 16 , Number  10
Pages  867 - 875

Alessandra A. de Souza , 1 , 2 Marco A. Takita , 2 Helvécio D. Coletta-Filho , 2 Camila Caldana , 2 Gustavo H. Goldman , 3 Giane M. Yanai , 4 Nair H. Muto , 4 Regina C. de Oliveira , 4 Luiz R. Nunes , 4 and Marcos A. Machado 2

1Empresa Brasileira de Pesquisa Agropecuária-EMBRAPA; 2Centro APTA Citros ‘Sylvio Moreira’/Instituto AgronÔmico-CP 04, CEP 13490-970, Cordeirópolis-SP, Brazil; 3Faculdade de Cincias Farmacêuticas de Ribeirão Preto-Universidade de São Paulo. Av. do Café S/N, CEP 14040-903, Ribeirão Preto-SP, Brazil; 4Núcleo Integrado de Biotecnologia-Universidade de Mogi das Cruzes. Av. Dr. Candido Xavier de Almeida e Souza, 200. CEP 08780-911, Mogi das Cruces-SP, Brazil

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Accepted 24 June 2003.

Xylella fastidiosa is a plant pathogen responsible for diseases of economically important crops. Although there is considerable disagreement about its mechanism of pathogenicity, blockage of the vessels is one of the most accepted hypotheses. Loss of virulence by this bacterium was observed after serial passages in axenic culture. To confirm the loss of pathogenicity of X. fastidiosa, the causing agent of citrus variegated chlorosis (CVC), freshly-isolated bacteria (first passage [FP]condition) as well as bacteria obtained after 46 passages in axenic culture (several passage [SP]condition) were inoculated into sweet orange and periwinkle plants. Using real time quantitative polymerase chain reaction, we verified that the colonization of FP cells was more efficient for both hosts. The sequence of the complete X. fastidiosa genome allowed the construction of a DNA microarray that was used to investigate the total changes in gene expression associated with the FP condition. Most genes found to be induced in the FP condition were associated with adhesion and probably with adaptation to the host environment. This report represents the first study of the transcriptome of this pathogen, which has recently gained more importance, since the genome of several strains has been either partially or entirely sequenced.

© 2003 The American Phytopathological Society