Development of a Vibrio Bioluminescence Gene–Set to Monitor Phytopathogenic Bacteria During the Ongoing Disease Process in a Non–Disruptive Manner

Abstract

Bioluminescence (lux) genes from Vibrio fischeri were cloned as a promoter–less gene set into the broad–host–range vector, pUCD4, resulting in the recombinant plasmid pUCD607 that was mobilized into a variety of plant pathogenic and symbiotic bacteria. All bacteria harboring the lux genes under the control of a constitutive promoter in pUCD607 constitutively bioluminesced. Virulence remained unaffected in pathogens carrying pUCD607, and bacterial invasion in host plant tissues was visually followed. The light generated is quantifiable and directly reflects the growth of the pathogen population in host tissue even before the onset of visual symptoms. pUCD607 is relatively stable in bacteria in planta in the absence of selective pressure. Bioluminescence can thus be successfully used to tag genetically engineered bacteria for subsequent monitoring during interactions with plants and in determining their fate in the environment.