April
2000
, Volume
13
, Number
4
Pages
421
-
429
Authors
Eugenio
Miguel
,
César
Poza-Carrión
,
Emilia
López-Solanilla
,
Isabel
Aguilar
,
Arancha
Llama-Palacios
,
Francisco
García-Olmedo
,
and
Pablo
Rodríguez-Palenzuela
Affiliations
Departamento de Biotecnología - Universidad Politécnica de Madrid, E. T. S. Ingenieros Agrónomos, Ciudad Universitaria s/n, E-28040 Madrid, Spain
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RelatedArticle
Accepted 13 December 1999.
Abstract
We have investigated the role of bacterial resistance to oxidative stress in pathogenesis. The oxyR gene from the pathogenic bacterium Erwinia chrysanthemi has been characterized. It is closely related to that found in Es-cherichia coli (88% overall amino acid identity). An E. chrysanthemi oxyR mutant strain was constructed by marker exchange. After induction with a sublethal dose of H2O2, this mutant was more sensitive to H2O2 and showed reduced levels of catalase and glutathione reductase activities, compared with the wild type. The oxyR mutant was unable to form individual colonies on agar plates unless catalase was added exogenously. However, it retained full virulence in potato tubers and tobacco leaves. These results suggest that the host-produced H2O2 has no direct antimicrobial effect on the interaction of E. chrysanthemi with the two plant species.
JnArticleKeywords
Additional keywords:
active oxygen species,
phytopathogenic bacteria.
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© 2000 The American Phytopathological Society