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Diversity among xanthomonads pathogenic on pepper and tomato
J B Jones1, R E Stall, H Bouzar
1Department of Plant Pathology, University of Florida, Gainesville, Florida 32611, USA. jbjones@nersp.nerdc.ufl.edu
Annual Review of Phytopathology
|March 12, 2004
Summary
Bacterial spot of tomato and pepper, caused by Xanthomonas campestris pv. vesicatoria, is now known to comprise distinct groups. These groups, A, B, C, and D, represent different species and subspecies, impacting disease management.
Area of Science:
- Plant Pathology
- Bacteriology
- Molecular Biology
Background:
- Xanthomonas campestris pv. vesicatoria, the pathogen causing bacterial spot in tomato and pepper, was historically viewed as a uniform species.
- Recent research has revealed significant genetic and phenotypic diversity within this pathogen.
Purpose of the Study:
- To re-evaluate the taxonomic classification of Xanthomonas campestris pv. vesicatoria based on new genetic and phenotypic data.
- To differentiate and characterize distinct groups within the pathogen population.
Main Methods:
- Comparative analysis of amylolytic activity and protein expression.
- Differential host reactions (tomato races T1, T2, T3).
- Serological testing with monoclonal antibodies.
- DNA restriction profiling and DNA:DNA hybridization.
Main Results:
- The pathogen was resolved into four distinct groups: A, B, C, and D.
- Groups A and B were reclassified as Xanthomonas axonopodis pv. vesicatoria and Xanthomonas vesicatoria, respectively.
- Group C exhibited distinct pathogenicity and serology, potentially representing a subspecies of Xanthomonas axonopodis.
- Group D was identified as Xanthomonas gardneri, a separate species pathogenic to tomato and pepper.
Conclusions:
- The traditional classification of Xanthomonas campestris pv. vesicatoria is outdated, with significant genetic divergence necessitating a revised taxonomy.
- The identification of distinct species and subspecies (X. axonopodis pv. vesicatoria, X. vesicatoria, X. gardneri) has implications for understanding disease epidemiology and developing control strategies.