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Growth of genetically engineered, bioluminescent, Xanthomonas campestris pv. campestris (Xcc), causal agent of black rot of crucifera, was followed in cabbage plants after the plants were prior inoculated with Xanthomonas campestris pv. vesicatoria (Xcv) or a nonvirulent strain of Xcc. Wound inoculation with Xcv induced a hypersensitive response and restricted the bioluminescent bacteria-host interaction if prior inoculation was carried out one day before challenge inoculation. Mist inoculation with Xcv was effective in restricting Xcc when the time period between inoculation end challenge was 6 days. In field studies, however, mist inoculation with Xcv or a nonvirulent strain of Xcc, one week before challenge inoculation with bioluminescent Xcc, did not significantly effect the growth and persistence of biolum inescent Xcc. The biolum inescent strain overwintered endophytically in cabbage and could be detected for many months throughout the vegetative period of the host.
The movement of genetically engineered, bioluminescent, Xanthomonas campestris pv campestris, causal agent of black rot in crucifers, was followed after wound or mist inoculation of susceptible and resistant host plants. Wound inoculation resulted in higher bacterial population levels in susceptible (Perfect Ball) as compared to resistant (Hancock) cabbage plants. More leaves became infected in the susceptible host and peak levels were reached after 4-8 days, but after 10-12 days in the resistant plants. Mist inoculation resulted in high levels of bioluminescent Xcc after 11-15 days in susceptible tissues only, unless entry was gained through damaged tissue of the resistant plant. In the field environment, Xcc was found endophytically after mist inoculation in susceptible cabbage only, but found to grow epiphytically for as long as 2 1/2 months to the same degree on resistant and susceptible host plants. Dispersal of the bacterium was limited and survival in the soil environment found to last for four months.
The bacterium Xanthomonas campestris pv. campestris (Xcc), causal agent of black rot disease in crucifers was tagged with the luciferase gene complex of the marine bacterium Vibrio fisheri. The growth of the bioluminescent strain in plants and the environment can be monitored by its light emissions. Susceptible cabbage plants were either mist, wound or debris inoculated in the field, soil was inoculated with debris or with suspension culture of genetically engineered Xcc. Plant, soil and air samples will be taken at biweekly intervals to monitor the spread of the bioluminescent bacterium within as well as outside the environmental release site. The transfer of exotic DNA to other bacteria in the environment will also be studied.