Multiphasic Analysis of Xanthomonads Causing Bacterial Spot Disease on Tomato and Pepper in the Caribbean and Central America: Evidence for Common Lineages Within and Between Countries

Abstract

Four hundred thirty-three xanthomonad strains isolated from tomato or pepper plants from 32 different fields in four Caribbean and Central American countries were screened for the ability to hydrolyze starch and sodium polypectate and for resistance to copper and streptomycin. Of these, 95 representative strains were further characterized by various phnetic tests, and 63 of these strains were then analyzed by genomic fingerprinting. Most of the strains (>90%) were tolerant to copper. However, there was much more variability in sensitivity to streptomycin. All strains in Guadeloupe and 93% of the strains in Barbados were sensitive to streptomycin. The majority of strains were typical Xanthomonas campestris pv. vesicatoria group A strains. In Barbados, however, a unique group of strains was identified that was serologically similar to group A strains but was amylolytic. These strains were designated A1. The occurrence of X. campestris pv. vesicatoria group B strains in Central America was found to be limited to two fields in Costa Rica and one in Guatemala. No group B strains were identified in the Caribbean, in contrast to common occurrence in the central United States and in South America. T3 strains were not found in this study, despite the recent increase of such strains in Florida and Mexico. Unique strains from Costa Rica belonging to the X. gardneri group were identified. Little linkage was found among phenotypic and rep-polymerase chain reaction (rep-PCR) genomic fingerprinting profiles of the pathogens except at the species/pathovar level; strains displaying virtually identical fingerprint profiles were found to correspond to distinct races and vice versa. The rep-PCR genomic fingerprinting analyses suggest that certain lineages may have evolved or predominated in specific regions or specific countries.