ENDOPHYTIC AND EPIPHYTIC GROWTH OF BIOLUMINESCENT XANTHOMONAS CAMPESTRIS PV. CAMPESTRIS IN AND ON RESISTANT AND SUSCEPTIBLE HOST PLANTS AND THEIR ENVIRONMENT.

Abstract

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.