PREDATION OF BDELLOVIBRIO BACTERIOVORUS ON ACIDOVORAX CITRULLI, THE CAUSAL AGENT OF FRUIT BLOTCH OF CUCURBITS

Acidovorax citrulli is a seed-borne and seed-transmitted bacterial phytopathogen, which causes bacterial fruit blotch (BFB) disease, a serious threat to the cucurbit industry worldwide. Although efforts have been made, neither BFB resistance has been found, nor efficient treatments to manage it. Bdellovibrio bacteriovorus belongs to a group of obligate predatory bacteria that prey upon gram-negative bacteria, and is found in many environments, including terrestrial, aquatic and animal gut. So far, only a few studies have assessed the potential of B. bacteriovorus as a biocontrol agent against plant and animal pathogenic bacteria. Moreover, many aspects of the interactions between the predator and its preys are not well understood. The objective of this research is to characterize the interaction between B. bacteriovorus and A. citrulli. Incubation of A. citrulli strains with B. bacteriovorus strains revealed two distinct phenotypes of A. citrulli strains: resistance or susceptibility to predation. We have characterized the dynamics of the two types of interactions and are now calibrating an assay that will allow screening a library of A. citrulli mutant to identify genetic traits that determine resistance or susceptibility to B. bacteriovorus.