DIVERSITY OF XANTHOMONAS-CAMPESTRIS PV CITRUMELO STRAINS ASSOCIATED WITH EPIDEMICS OF CITRUS BACTERIAL SPOT IN FLORIDA CITRUS NURSERIES - CORRELATION OF DETACHED LEAF, MONOCLONAL-ANTIBODY, AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ASSAYS

The heterogeneity of 194 previously uncharacterized strains of Xanthomonas camperstris pv. citrumelo isolated from citrus bacterial spot epidemics in for citrus nurseries in central Florida was evaluated by virulence reactions on detached leaves, reaction to a panel of monoclonal antibodies (MAbs), and reaction to a panel of restriction fragment length polymorphism (RFLP) probes. Detached-leaf assays were performed on the 194 strains that had been differentiated into five serological groups based on reactions with six MAbs. A subset of 27 strains, selected because of their diverse reactions to MAbs and the detached-leaf assay, were differentiated into five reaction types by RFLP analysis. There was good agreement between serological reaction patterns and RFLP results. Both assays were capable of distinguishing strongly aggressive from less aggressive strains as indicated by detached-leaf assay. In addition, MAb and RFLP assays often detached the same unique strains within the population of strains from individual nurseries. The assays also differentiated groups of strains originating from different foci of infection in one nursery.